Refer to “American Gas Association”
- Abrasion Resistance:
This is the ability of the material to withstand abrasion.
- Absolute Zero:
It is the lowest possible temperature on the thermodynamic temperature scale, at which the energy of the particle is zero. Absolute zero is zero on the Kelvin scale, which is equivalent to -273.15°C or -459.67°F.
- AC (Å):
Refer to Alternating Current
- AC Line Frequency:
This refers to the number of cycles measured in every second of an alternating current (AC) sine wave. AC line frequency is measured in Hertz (Hz), and 50 Hz or 50 cycles is set as a standard. The standard in the United States is 60 Hz.
This is both alternating and direct current. Accelerated Aging: This is a process of establishing a shelf life or lifespan of a product through series of tests where it may be subjected to aggravated conditions of humidity, heat, oxygen, vibration, radiation, sunlight, and so on.
This is a difference between the value measured by the instrument and the true value or the corresponding value. The accuracy of the sensor is measured on NIST (NBS) standards.
Any change in process variables can affect the output of equipment. The response of this change is known as action. Refer to “Reverse Action and Direct Action”.
- Active Components:
These are electronic devices whose properties are altered on the application of electric current. Transistors, diodes, and integrated circuits are active components.
This refers to the existing value of the variable that is controlled.
It may be represented by various symbols such as a label, name, register, a location in the storage, location of a station in a communication network, or a register or other data destination or data source.
It is a type of thermocouple alloy, which is a trademark of Harrison Alloys Company. It comprises 45% nickel and 55% copper, and is used as a negative conductor in ASTM Type E, J, as well as T thermocouples.
This is any form of a visual and/or audible signal, which suggests that the process has fallen or exceeded above or below its set point. For instance, an alarm may produce a visual or audible signal to indicate the rise or fall in temperature.
- Alarm Dead Band:
The process signal is changed to return the alarm to a normal state or to activate it. This change is known as alarm dead band.
- Alarm Delay:
This is the time of lag that occurs before the activation of an alarm.
- Alarm Hysteresis:
This is a difference between the values, where an alarm may turn OFF from turning ON or turn ON from turning OFF.
- Alarm Module:
- 1) It features a software and hardware combination that is designed to alert a user regarding a problem or to perform a response action to a problem existing in the thermal system. An alarm module helps create a safer working environment.
- 2) It may also refer to the typical feature in the National Association of Food Equipment Manufacturers (NAFEM) data protocol model. This helps determine the existence of a particular alarm condition by setting criteria and comparing the alarm object attributes.
- Alarm Silence:
This feature helps disable the output of the alarm.
- Alloy #11®:
This is a registered trademark of Harrison Alloys. It is a type of compensating alloy, which is made of 1% nickel and 99% copper. Mainly used for making the negative conductor, the alloy is used along with pure copper to develop a thermocouple extension wire, which is used in ASTM Type S and R thermocouples.
- Alloy 188®:
This is cobalt - nickel - chromium - tungsten based superalloy, which possesses high strength, and can strongly resist corrosion and oxidation. The alloy also possesses excellent welding and forming characteristics, which make it an ideal choice for applications in the nuclear, aerospace, chemical, and process industries. Being a registered trademark of Haynes International, this alloy is also known as HAYNES® 188 alloy.
- Alloy 203/225:
The alloys of this type has either of the two compositions: two percent chromium (225) and 98 percent nickel or 10 percent chromium (203) and 90 percent nickel. They are used to create wire conductors or extension wire conductors for Type D thermocouples or W3Re/W25Re thermocouples that are designed for applications up to 400°F or 200°C.
- Alloy 214®:
It is a nickel-aluminum-chromium-iron alloy, which assures excellent oxidation resistance at high temperatures. It is also well known for its resistance against nitriding, corrosion, and carburization in chlorine-bearing atmospheres. Alloy 214® is mainly used for making sensor probe sheaths, and is a trademark of Haynes International.
- Alloy 230®:
It is a nickel-chromium-tungsten-molybdenum alloy, which possesses excellent welding and forming characteristics, as well as combines several beneficial features. This alloy exhibits brilliant oxidation resistance, strength, and thermal stability at high temperatures. It is used for creating sensor probe sheaths. Alloy 230® is a trademark of Haynes International.
- Alloy 405/426:
Alloy 405 has a composition of one percent silicon, two percent manganese, and 94.5 percent nickel. Alloy 426 is made of 20 percent copper and 80 percent nickel. Both these nickel alloys are known for their high ductility, and excellent oxidation resistance over their temperature range of use (<870°C (1600°F)). These alloys are widely used for making extension wire conductors for Type C (W5Re/W26Re) thermocouples.
- Alloy 556®:
It is a nickel-iron-cobalt-chromium alloy that assures brilliant resistance to carburizing, sulfides as well as chlorine-bearing environments. The alloy also has excellent welding and forming characteristics. It is a trademark of Haynes International.
- Alloy HR160®:
This is a cobalt-nickel-silicon-chromium alloy, which exhibits excellent resistance to corrosion attacks at high temperatures. The alloy can withstand temperatures up to 2200°F (1204°C), and exhibits brilliant resistance to sulfides. Alloy HR160® is a trademark of Haynes International and is used to create probe sheaths for sensors.
- alpha (α):
This is a temperature coefficient of resistance, which is measured in ohms/ohm/°C. It is the electrical resistance factor of a material, which changes for each °C in temperature. For pure metals, the value of alpha is positive, whereas it is negative for some elements, and near to zero for a few metal alloys. Alpha values are set for different resistance temperature detectors (RTDs). For instance, the values are 0.003916 Ω/Ω/°C (JIS) or 0.00385 Ω/Ω/°C (DIN) for platinum RTDs.
- Alternating current (Å):
It is an electric current that reverses its direction, and as a result, it may have negative and positive values. This reversal takes place at regular intervals.
It is an alloy comprising 95 percent nickel, two percent manganese and aluminum (each), and one percent silicon. This alloy is used for making thermocouple extension wire and a negative conductor for Type K thermocouple. Type K is an ASTM calibration. It is a registered trademark of Concept Alloys.
- Ambient compensation:
See “compensation, ambient.”
- Ambient temperature:
See “temperature, ambient.”
- American Gas Association (A.G.A.):
It is an American trade organization that represents natural gas companies, gas appliance manufacturers, and gas producers. The organization tests gas-related accessories and appliances to A.G.A standards and ANSI standards.
- American Wire Gauge (AWG):
This is a wire gauge system used in North America to ascertain dimensional characteristics of solid, round, non-ferrous, electrical current-carrying wires. It is also known as Brown & Sharpe wire gauge (B&S), and wire dimensions is provided in ASTM standard B 258.
This is an instrument used to measure the electric current in any circuit.
It is defined as the rate of electric flow in any circuit. Ampere is the SI (International System of Units) unit to measure electric current, and equals the flow of one coulomb in a second. Coulomb is a charge carried by an ampere in a second. One coulomb equals to 6.25 x 1,018 electrons per second.
It a method of data representation of a signal in terms of physical quantities. This term is mainly used for representing electric signals. It may also be used for hydraulic, mechanical, pneumatic and other signals, too.
- Analog Output:
It is a variable signal that is employed to represent a set point value or a process value.
It is a heat treatment process performed to remove internal stresses of a solid. Annealing helps improve the ductility of metals by reducing its toughness, thereby making it useable. In this technique, the metal is heated to a temperature below its melting point, and allowed to cool at ambient temperature. It is suitable for various types of glasses and metals.
It is a visual display used in various industrial systems to indicate the status of various active electric circuits and systems.
It is an abbreviation of the American National Standards Institute, which oversees the development of consensus standards for processes, products, and systems in the United Status. ANSI also coordinates the American standards with worldwide standards, thereby ensuring worldwide acceptance for American products.
Refer to anti-reset windup.
- Anti-reset Windup:
This is also known as anti-reset, and is a situation or phase in a PID temperature controller that helps stabilize the system. In this, the controller resets the circuit and prohibits it from functioning if the temperature goes beyond the proportional band.
- Application Layer (OSI Layer 7):
The Application Layer is the layer of the seven-model Open Systems Interconnection (OSI) model and it is present over the Presentation Layer. Application Layer (OSI Layer 7) is the highest layer of the OSI model. It comprises protocols that focus on different process-to-process communication across the network, as well as assures a reliable communication interface. Web browser or email applications are the examples of this layer, and they ensure data exchange on the internet.
This is an abbreviation for Address Resolution Protocol, which is a low-level TCP/IP protocol that helps identify the physical address of a device as well as media control address (MAC) address, thereby enabling swift communication between devices on a local area network (LAN).
This is an abbreviation for the American Society of Mechanical Engineers. This is a multidisciplinary engineering organization that is involved in training and professional development, development of codes and standards, education, research, publications and conferences, and government relations. This non-profit organization conducts several technical conferences every year, and is also known for its technical publishing operations.
This is an abbreviation for the American Society for Testing and Materials. It is a well-known organization that develops as well as publishes technical standards for a variety of services, materials, systems, and products. The organization mostly publishes voluntary consensus standards that operate internationally.
This is a gaseous envelope covering the earth.
- Atmosphere (atm):
It is the standard pressure or a reference pressure, which is equal to the atmospheric pressure at the level of the sea. The value of standard pressure is 101 325 Pa or 1.013 25 bar. It is basically a pressure exerted by 29.92 inches (760 mm) of mercury at sea level. This measurement is in reference to tests conducted at the latitude of 45 degrees.
- Atmospheric Pressure:
This is also known as barometer pressure, and is measured as pounds per square inch or grams per square centimeter. It is basically the pressure within the earth’s atmosphere or other planets.
- Automatic Mode:
This is a feature of a PID controller that allows setting the output controls according to the set point and the process variable (PV).
- Automatic Power Reset:
This is a feature in controllers where the output is not affected with a power outage. The output is automatically re-energized after the power restoration. This automatic re-energization of output is affected by temperature. It will work perfectly as long as the temperature remains in controlled limits.
- Automatic Prompts:
These are microcontroller-produced data entry points, where the user is informed to enter a proper control value.
- Automatic Reset:
This is an important function of a PID temperature controller or a PI temperature controller, where the temperature of the process is set after the stabilization of the system.
It is a feature of a PID controller that automatically sets its temperature control values to match a specific thermal system.
- Auxiliary Output:
This output is independent of the primary control output, and it controls activities that may not be part of the primary control output. This may include activities of devices such as buzzers and lights, gas purges, door latches, etc.
Refer to “American Wire Gauge”.
- B&S Gauge:
The Brown and Sharp Sheet Metal Gauge is the dimensional standard used in North America. Refer to “AWG”
- BTE Thermocouple Holes:
These holes are created by between-the-element (BTE) ceramic tubes. They are electrically isolated, and created in the heaters to track element temperature. The thermocouple holes assure over-temperature protection as well as help improve the life of the heater.
It is a region above and below the point, where proportional control occurs.
- Base Metal Thermocouple:
It is a type of thermocouple where the conductor is made of base metallic element alloys such as nickel, copper, and iron. The type J, T, K, and E are base metal thermocouples, and they are ASTM calibrated. Base metal thermocouples are ideal for industrial applications involving low temperatures.
- Baud Rate:
This is defined as the rate of information transfer in a communication channel. This term is most commonly used in the electronics and telecommunications industries. It is the unit for modulation rate or symbol rate and represented in pulses per second, bits per second, or symbols per second.
Refer to “Block Check Character.”
- Bend Radius (Standard):
This is a minimum radius of curvature. It is a radius to which a wire or a sensor can be bent without affecting its transmitting capabilities or shelf life. Bend radius (standard) is a function of diameter (wire or sensor).
- Beryllia/Beryllium Oxide:
This is an inorganic compound that is identified with its white color. The compound has a high melting point, and it possesses high dielectric strength and high thermal conductivity. Berylllia is used as an electrical insulator in ceramic thermocouples. Its thermal conductivity is higher than most metals and non-metals, except diamond. The compound is depicted by a formula BeO. Particles and dust of this compound are toxic, and they require special precautions while handling.
- Blackbody or Black Body:
This is an ideal physical body that absorbs electromagnetic radiations that fall on it. The body can absorb radiations at all frequencies and angles, and also it radiates the maximum energy for a given temperature. The black body has an emissivity of ε = 1.0A at thermal equilibrium. Refer to “emissivity” for more details.
It is a group of similar things that are handled as a single unit.
- Block Check Character (BCC):
It is a special character in the transmission block to check error detection. This character is widely used in telecommunications transmission.
- Blocking Voltage (BVDSS):
A maximum voltage accepted by the MOSFET without affecting its current protecting capabilities.
- Boiling Point:
This is the saturation temperature at which the liquid’s vapor pressure becomes equal to its external pressure. Hence, a liquid’s boiling point will entirely depend on the atmospheric pressure. The boiling point decreases with a reduction of external pressure. For instance, at sea level, the water’s boiling point is 100ºC, whereas it reduces to 93.4 ºC at 6,600 feet.
It is the action of joining two materials, which may be similar or dissimilar using adhesives. This joining may be performed to improve the durability or security. For instance, in lead wires and temperature sensors, bonding is performed to protect them from moisture.
A flexible covering made of plaited ceramic or textile fibers, which is used to create electronic insulation on electrical conductors. At times, metallic filaments are also used to produce a braided cover. The braided cover produced from metallic filaments help shield conductors from electrical noise as well as help improve their electrical noise.
- Bright Annealing:
This is a surface treatment technique employed to produce smooth surfaces. In this technique, metal sheets are made to pass between rollers to produce a smooth surface. This technique is mainly used for processing stainless steel cold rolled sheets, aluminum sheets, stainless steel backplates, and cold rolled strip steel sheets.
It is a graphic interface or program that displays HTML files. The browser is mainly used to navigate the World Wide Web (WWW).
- British Standards Institution (BSI):
This is also known as BSI Group, and it is responsible for producing technical standards for a wide range of services and products. The organization also offers certification to businesses.
The British Thermal Unit (BTU) is a basic unit of heat, and it is defined as the heat required to increase the water temperature by a degree Fahrenheit. This is basically considered for one pound of water. One Btu is equal to 0.293 watt-hours, similarly, 3412 Btus make up one-kilowatt hour. The metric counterpart of Btu is calorie. See ‘Calorie’.
- Bumpless Transfer:
Under this, the PID controller or other controllers are expected to continue with their desired action even if they are in transition from manual to auto mode or vice-versa.
- Burst Fire:
A power control method for turning on and off full AC cycles. During this, the radio frequency interference (RFI) is minimized by switching the power close to the zero-voltage point of the AC sine wave. Thus, the term is also referred to as zero-cross fire sometimes. It is observed that variable time-base burst fire transits or holds AC cycles to attain the power level.
In this process, an additional sheath is added to the tube to increase its non-standard or larger diameter.
- B&S Gauge:
It is an assembly of conductors to be used for transmission of electrical signals and power.
- Calendar van Dusen Equation:
This equation helps describe the relationship between temperature (T) and resistance (R) of any platinum resistance thermometer (RTD).
It is the comparison of measurement values produced by test equipment against a better or equal standard.
- Calibration Accuracy:
The difference between the value produced by test equipment and a known standard or physical constant.
- Calibration Offset:
It is basically an adjustment done to the device to eliminate or reduce the difference between the actual value and the indicated value.
It is the basic unit of energy. It is defined as the energy required to raise the temperature of one gram of water through 1 degree Celsius. The value of calorie is now defined as 4.1868 joules.
- Carbon Potential:
It is the capability of a furnace to increase the carbon content of steel during various heat treatments. When the term is used in regards to the atmosphere, it is defined as the amount of carbon content in an iron sheet at a given time. For this, the iron sheet is considered to be in equilibrium with the surrounding atmosphere.
- Carbon Potential Control:
It is the ability to control the carbon content of steel in heat treatment furnaces.
- Cascade Control:
It is the control algorithm, where the output of a one control loop serves as the target of the next loop. The control action is determined by the second loop.
- CAT 5:
It is also known as Category 5 cable, and is widely used as twisted pair cables for the transmission of video and telephone signals. The cables of this type are manufactured to meet the regulatory requirements of TIA/EIA 568-A standards. Widely used for computer networks, these cables can support network speeds from 10 Mbps to 100 Mbps. These cables are terminated with RJ45 connectors in 100 m lengths.
Am abbreviation for confidential disclosure agreement. It is a legal document that describes conditions of sharing confidential information between parties. Most companies use detailed and standard CDAs to protect their intellectual property.
A certification mark that conforms to safety, health, and environmental protection standards for products to be sold in Europe. This mark is depicted by the CE logo, and may also include information of the body that is involved in the assessment procedure.
- CE Compliant:
It is the compliance of a device with CE requirements. This term is mainly used to depict electromagnetic capability and safety.
- Celsius or Centigrade:
A temperature scale used by the International System of Units. The scale is based on freezing point of water (0 °C) and boiling point of water (100 °C) at 1 atm pressure. The conversion formula for: Celsius to Fahrenheit is [°F] = [°C] × 9⁄5 + 32; Celsius to Kelvin is [K] = [°C] + 273.15; and Celsius to Rankine is [°R] = ([°C] + 273.15) × 9⁄5.
- Central Processing Unit (CPU):
It is the electronic circuitry inside the computer that helps interpret the instructions and enables their execution. CPU is built on a single IC chip and it may comprise peripheral interfaces, memory, and other important computer parts, too.
- Ceramic Fiber:
It is a lightweight and low-density alumina silica-fiber, which is used as a refractory material.
- Ceramic Insulation:
These are insulating materials made of metal oxides. Ceramic insulators provide high dielectric strength, and they can easily withstand high temperatures. These insulators are mainly used to build thermocouple wires or heater elements.
Computational Fluid Dynamics is a numerical technique employed to analyze fluid flow. It is used to simulate the Navier stock equation’s behavior that is mainly used to identify a fluid flow.
It is Cubic feet per minute, and is a standard for measurement of airflow. This is defined as the velocity of airflow inside and outside the space. It is used in heating, bathroom, and ventilation systems.
Refer to ‘control channel’.
It is on-off cycling of a mercury replacement or electromechanical relay. This rapid action occurs due to the insufficient bandwidth of controller. Chatter is caused due to little hysteresis, excessive gain, and short cycle time.
- Chemical Resistance
This is the ability of any material to resist attack by environment, chemicals, and radiation. The attack may take different forms such as erosion, permeation, or corrosion.
It is an alloy comprising 10% chromium and 90% nickel, and it is widely used for making positive conductors for Type K (chromel – alumel) and Type E ( chromel – constantan) thermocouples. Type K and Type E are ANSI consideration. Chromel® is a registered trademark of Concept Alloys, Inc.
A path that supports the flow of electric charges. It is an unbroken or continuous path through which electrons flow. Current or charges can only flow through a closed circuit. It may comprise several electromagnetically or electrically-connected components and devices.
It is a workstation or a desktop computer that requests information from a server. This term is half part of the client-server system. Email is an example of the client-server system.
- Closed Loop:
A set of electronic or mechanical devices that are designed to automatically regulate a process variable to the desired set point. They do so without any human intervention.
This term stands for: Cubic Meters per Minute, which is a measure of airflow; Coordinate Measuring Machines, which are dimensional measuring machines used in manufacturing; Capability Maturity Model is a tool used for assessing various processes involved in software development. It is a registered trademark of the Software Engineering Institute (SEI).
Computerized Numerical Control is an automated control or programmed control of machines and 3D printers. The machines controlled by CNC utilize software designs. CNC machines can process a wide range of materials including plastic, metal, ceramic, wood, and composite.
- Coaxial Cable:
A type of electrical transmission cable that has an insulated conductor placed inside a metallic shield or tube. These tubes are made of braided wires, which help protect the electricity carrying inductor from noise or electrical interference.
- Cold Junction:
It is a connection point between the measuring instrument, as well as the thermocouple metal. This is also referred to as the reference junction. Refer to “reference junction.”
- Cold Junction Compensation:
This is necessary for measurements involving thermocouples. It means compensating for the temperature at the cold junction.
- Color Code:
It is a color system that identifies individual conductor wires. There is a typical color code to identify the type of thermocouple in thermocouple circuits. These color codes vary across different countries. For instance, European countries adhere to IEC wiring color codes, and the US follows color codes with ASTM designations.
- Common-Mode Line Filter:
It is an electronic filter that is used to filter noises between the equipment and the line.
- Common-Mode Rejection Ratio:
An ability of an electronic device to reject common-mode signals. The common-mode signals are those that occur simultaneously on both inputs.
It refers to the use of computer-generated messages to link various components. Refer to “Baud rate” and “serial communications”.
- Compensated Connectors:
A type of thermocouple connector that uses compensating alloy contacts. The connector may also use an actual thermocouple alloy contact. These connectors are known to retain their metallic circuit properties, and they reduce errors considerably.
- Compensating Alloy:
It is an alloy that may have a resistance similar to any actual thermocouple alloy. These alloys are affordable alternatives to lead wires used for extension purposes. For instance, Alloy #11 is a compensating alloy for platinum thermocouple sensors. It is used as a lead wire for the thermocouple.
- Compensating Loop:
It is a pair of lead wires that possess similar resistance as their actual counterparts. These lead wires are not RTD connected. During the temperature measurement, the compensating loop helps correct errors generated by lead wire resistance.
- Compensated, Ambient:
The instrument adjusts itself to the changes in the environment and this is known as compensated, ambient. The sensor provides an accurate reading if it is maintained at a constant ambient temperature. Its output will vary when the temperature changes.
- Computer Ground:
It is a line for managing the ground connections of microprocessors or computers. This ground is different from the safety ground.
A process through which electricity or heat is transmitted through the substance without the movement of material. This transmission is initiated by the difference of electrical potential or the difference of temperature in adjoining regions.
It is defined as the property of a material to conduct electricity. Conductivity is a reciprocal of resistivity, and is measured in the current passed per unit of voltage. Siemens per meter (S/m) is the SI unit of conductivity. The thermal conductivity is defined as the ability of a body to conduct heat. It is measured as the heat conducted through per unit area, per unit time, and per unit of thickness for a difference of one-degree kelvin.
- Connection Head:
This is housing on a sensor assembly, which enables electrical connections through a terminal block. It also allows the attachment of conduit-tubes as well as protection cables and tubes.
It is the capability of a computer-controlled device for communicating with other systems or devices.
It is a popular copper-nickel alloy made of 45 percent nickel and 55 percent copper, and is known for its high resistance. Constantan is mainly used for creating negative conductor in Type E, T, and J thermocouples, which have ASTM configuration.
- Continuity Check:
A test conducted on a finished assembly to check the continuous flow of current throughout the entire length of material. This test also helps identify a short circuit between different conductors.
- Control Accuracy:
It is the degree of correspondence between the ideal value in a control system and the controlled variable. Or it can be defined as the ability to manage a process at the desired or ideal setting. It is a comprehensive function of several features, including controllers, sensors, heaters, loads, and inefficiencies.
- Control Action:
The control output response relative to the difference between the set point and the process variable. For cooling, which is a direct action, the output increases when the process raises above the set point. For heating, which is a reverse action, the output increases when the process goes below the set point.
- Control Channel:
It is similar to control loop, and in life sciences, this term may indicate a data communications feature.
- Control Loop:
The building block of industrial systems. It may or may not have feedback from a load to the controller. In a closed loop, the system will have feedback from a single load, whereas in an open loop, there is no feedback from the load to the controller.
- Control Mode:
It is the type of action used by a controller. For instance, this may be PID, on-off time proportioning, manual or automatic, or a combination of all these actions.
Refer to “control” and “accuracy”.
A type of heat transfer in gases or liquids, where heat is transferred through movement from the region of higher temperature to the region of lower temperature.
A malleable, ductile, and soft metal with atomic number 29 and symbol Cu. It is used as a positive conductor in Type T thermocouple. Type T is an ASTM configuration.
Cycles per second is a unit of frequency, and it is now replaced with hertz (Hz).
Refer to “Cyclic Redundancy Check”.
A phenomenon through which the signal transmitted from one channel or circuit of a transmission system affects another channel or circuit in an undesired way. It is mainly caused due to conductive, inductive, and capacitive coupling between two channels or circuits.
This indicates low temperatures in the range of 0° to -200°C (32° to -328°F).
It is the behavior of materials at extremely low temperatures.
Canadian Standards Association is an independent organization that develops industrial and commercial standards for organizations in Canada. It also provides product testing and certification services to organizations.
It is the Underwriters Laboratories, Inc. (UL®) recognition for Canada. In many cases, C-UL approval may be a substitute for approval of the Canadian Standards Association (CSA). All references to the C-UL® refer to the original UL® file.
A thermocouple alloy made of 45% nickel and 55% copper. It is used to make negative conductors for Type T, E, and J thermocouples. Type E, T, and J are ASTM configurations. The alloy is a registered trademark of Carpenter Technology.
It is the rate of flow of electrons past a region or charge. The SI unit of current is ampere. Refer to “ampere”.
- Current Transformer:
A device designed for measuring the electric current.
- Cycle Time:
The time needed for a controller to complete one cycle – on-off cycle. This is expressed in seconds.
- Cyclic Redundancy Check (CRC):
An error-detection code used to identify any accidental changes made to raw data. This detection code is mainly used in storage devices as well as digital networks.
- Data Link Layer (OSI Layer 2):
It is the second layer in the seven-layer Open System Interconnection (OSI) protocol. The layer lies between the Physical Layer and the Transport Layer, and it has two sub-layers – the Logical Link Control (LLC) and the Media Access Control (MAC).
- Data Logging:
It is the process of data collection and storage over a period of time. This is done to record and analyze the data-based actions or events of IT environment, system, and a network.
In this type of current, the flow of the electric charge is restricted to one direction.
- DC Resistance:
Refer to “resistance”.
It is the band or the range observed in a signal processing system or a control system, where the input values produce no output. In this band, specific conditions are also placed on the output values. This is also known as a dead zone or a neutral zone.
- Dead Zone:
Refer to “Deadband”.
The output shift is induced in the thermocouple by altering its alloys. This phenomenon is known as decalibration, and it is also the phase where the thermocouple no longer conforms to any standards.
- Default Parameters:
These are the values programmed and permanently stored in the software.
This is the increment of variables in a system. The point or stage in the phase of a cycle, in electrical or mechanical cyclic scales. One cycle equals 360 degrees.
This is the degree of compactness of a substance or mass per unit volume of a substance. It is expressed in kilograms per cubic meter or pounds per cubic feet.
It is the instantaneous rate of change of a function, and is commonly referred to as the rate of change. Refer to “PID”.
- Derivative Control (D):
The term in the PID control algorithm. It is the action that helps improve the performance of several PID control loops by slowing the rate of change of the controller output. This action is mainly used to reduce the magnitude of undershoot and overshoot. During its application, an instantaneous change is observed in the control output. This change is brought by the process variable (PV) that decreases against the increase in time derivative (TD), which is often units of seconds.
- Deutsche Industrial Norm (DIN):
A dimensional, technical, or a scientific standard developed by the German Institute of Standardization. There are more than thirty thousand DIN standards for every field of technology and many of them are globally recognized.
A departure from any accepted or desired value. It is the measure of the difference between the true value and the observed value.
- Deviation Alarm:
It is a type of setting that raises an alarm when a process variable exceeds or falls behind a degree of the set point. In a temperature controller, the alarm can be easily referenced at a fixed number of degrees, above or below, the set point.
- Dynamic Host Configuration Protocol (DHCP):
A network management protocol that dynamically assigns a unique IP address to each device operating on a network. This makes communication of the device with other IP networks much easier.
This is the rate of current change. The increased di/dt can damage power controllers that are being used for large resistive loads. In such cases, inductors are used to protect these power controllers.
An insulator that has low electrical conductivity. The dielectric insulator can be easily polarized by an electric field.
- Dielectric breakdown:
It is the point at which a dielectric substance starts conducting electricity. Dielectric or electrical breakdown occurs when excess voltage is applied to the insulator.
- Dielectric strength:
It is the voltage required to create a dielectric breakdown of the material. This is expressed in terms of volts per unit thickness. IEC 60243 is the standard employed for testing a material’s dielectric strength.
- Differential control:
The control action is driven by a change of the control error. This term is used in reference to a controller where a control algorithm is used. The setpoint on the algorithm provides a difference between any two processes. The controller refers to the difference value and manipulates the second process to hold it at the same set value as the first controller.
- Differential Mode Line Filter:
It is the device used to filter the noise between two separate power lines.
It is the movement of particles between the regions of higher concentration to the regions of lower concentration. In this type of movement, molecules of different substances are mixed gradually through a thermal movement.
- Digital Adaptive Filter:
The filter has self-adjusting characteristics, and it rejects high-frequency noise spikes.
- Digital Filter (DF):
This is a device used in signal processing applications to improve certain aspects of a signal. These changes are introduced through mathematical operations that are performed on a discrete-time signal.
Refer to “Deutsche Industrial Norm.”
- Direct Action:
This is a type of control action where the output increases in response to the increase in the process variable. Most cooling applications utilize a direct action.
- Direct Current:
Refer to “DC”.
- Display Capability:
This is the capability of an instrument with a digital display to showcase the entire possible range of a particular value or parameter.
- Dissipation Constant:
The amount of power required by the thermistor to increase its temperature by 1℃ in still air.
- Distributed Zero Crossing (DZC):
This output is used for fast-acting electrical loads where the output on-off state of each cycle of the AC line cycle is calculated. For this calculation, the electrical noise of the power is reduced by switching it at the zero-crossing point. Refer to “zero cross”.
Domain Name System is a decentralized naming system for computers or other resources that are connected to a private network or the Internet. It helps arrange domain names in alphabetical order and translates them into IP addresses.
- Drain Wire:
A type of uninsulated wire that is used as a ground conductor in cables and wires.
It is a metalworking process where the material is stretched by action of tensile strength.
A change in value that is observed over a long time. The impetus for change could be ambient temperature, humidity, contamination, component aging, or anything.
This is the difference observed in the actual value and the set point, post system stabilization in proportional controllers. The droop is corrected by the reset component of PID control.
- Dual Element Sensor:
A sensor featuring two sensing elements which are independent of each other. These sensors are mainly used to measure temperature gradients or identify redundancy of a single point sensor.
- Duplex Control:
The single process output is divided into two outputs using enhanced software. For instance, a 4 to 20mA output is divided into a 12 to 20mA reverse action (heating output) and 4 to 12mA direction action (cooling output).
- Duplex Wire:
A type of wire or cable that has two insulated conductors. These conductors may be twisted or aligned parallel to each other. The drain-wire conductor is an example of duplex wire.
- Duty Cycle:
The ratio of time for which the signal of the system is active. It is expressed as a ratio or percentage.
The change in voltage, with respect to time. Acceleration is a function of dv/dt. When dv/dt exceeds beyond a certain point, it can have a damaging effect on a silicon controlled rectifier (SCR) power controller.
- Data Link Layer (OSI Layer 2):
- Earth Ground:
A good conductor metal rod connected to the earth till a few feet inside to avoid shocks and electromagnetic disturbances. Generally, copper is used for the purpose.
The ratio of useful output produced by a machine with the total amount of energy consumed and heat generated.
Refer to “Electronics Industries of America.”
- EIA/TIA -232, -422, -423 and -485:
These are the data and telecommunication standards set by the Electronic Industries Alliance/Telecommunication Industries Association. It was earlier referred to as Recommended Standard (RS).
- EIA/TIA-232 (formerly RS-232):
This standard was initially set for serial communication transmission of data. This Electronics Industries of America (EIA) and Telecommunication Industry Association (TIA) standard is for interface between data communications and data terminal equipment that are used for serial binary data interchange. RS-232 interfaces, however, are still used despite low rate of transmission.
- EIA/TIA-485 (formerly RS-485):
An Electronics Industries of America (EIA) and Telecommunication Industry Association (TIA) standard that defines the electrical characteristics of receivers and drivers in communication systems. This standard enables more than one receivers and drivers in a bus configuration.
A polymer that can be stretched to its upper limit without damaging or disturbing the original shape.
- Electrical Interference:
Disturbance caused by electrical equipment or transmitters or other electromagnetic disturbance, which limits or degrades the device performance. Also called “electromagnetic interference.”
- Electrical Noise:
Refer to “noise.”
- Electrical-mechanical relay:
Refer to “relay” and “electromechanical relay.”
- Electromagnetic Compatibility (EMC):
The interaction between the electrical and electronic equipment and their surrounding electromagnetic field. This is essential to avoid electromagnetic interference caused by the emission of electromagnetic waves by several electronic devices in the same area.
- Electromagnetic Interference (EMI):
All electronic devices emit electromagnetic waves. When there are more than one such devices in one room or area these waves interfere with each other. This produces noise and disturbance that hamper the performance of an electronic device or an electrical circuit. This is also called radio-frequency interference.
- Electromechanical Relay:
This is a switch meant for high-power electrical devices. These are used in electrical machines to control one or more circuits with just one signal. Electromechanical relays are not recommended for PID controls.
- Electromotive Force (EMF):
The potential difference between two points in a circuit which causes the current to flow. This is measured in volts.
- Electronics Industries of America (EIA):
An organization in the US that sets standards for electronics and data communications.
This is an electrochemical process, which reduces the roughness of a metallic surface by removing metal particles to make it smooth. It is the opposite of electroplating.
- Electrostatic discharge (ESD):
A flow of low amounts of current between two electrically charged objects. This happens due to contact or dielectric breakdown and may hamper the electronic device.
Refer to “electromagnetic compatibility.”
Refer to “electromotive force.”
Refer to “electromagnetic interference.”
All objects emit thermal radiation above the absolute zero temperature. Emissivity is the ratio of this radiation emitted from an object’s surface to the radiation emitted from the surface of a perfectly blackbody at the same temperature. Emissivity depends on physical features of a surface such as plain or rough among others.
A process or reaction in which heat or energy is absorbed from the surroundings.
- Engineering units:
Some units used in the US are SI units while their counterparts are English units that are not followed in the US. So the measurement units need to be defined. For instance, force is measures in pound force, as well as newton. Newton is an SI unit, while pound force is an English unit.
The amount of heat absorbed or released in a process, at a given temperature, pressure and volume. It is the total heat content of a system expressed in units of Btu/lb or Joules/gram.
Erasable, programmable, Read-Only Memory; it is the chip that holds data when the computer is turned off or in case of a power cut.
When the actual reading or output does not match with the required value due to either machine fault or limitations of humans who note the readings.
Refer to “electrostatic discharge.”
Ethylene tetrafluoroethylene, or Tefzel®, the DuPont brand. Refer to “Tefzel.”
A local area network (LAN) protocol with a wired connection that is used to connect computers and electronic devices in a small area such as an office or a building.
An input or output signal that indicates an on or off state of a machine that helps control the running of a process or machine or serve as an input to the next event.
When two or more entities in a process react with each other, heat or energy is released. Such chemical reactions are exothermic.
- Explosion-Proof Enclosure:
These are secure and robust cabinets comprising switches, sockets, knobs, controls, and more to protect the surroundings from short circuits or other electrical hazards. These enclosures are designed to withstand high temperatures and an explosion of gases inside to safeguard the outside environment, and are useful in hazardous locations.
- Exposed Junction:
A type of thermocouple measuring junction formed by joining two thermocouple conductors. However, these conductors are exposed outside the thermocouple sheath and hence are vulnerable to damage or attacks.
- Extension Wire:
Refer to “thermocouple extension wire.”
- External Transmitter Power Supply:
An external DC voltage source that powers transmitters with the help of recorders and controllers.
A process by which a metal is formed or shaped by cross sectioning to create a desired shape.
- Earth Ground:
The temperature scale that considers 32°F as the freezing point of water and its boiling point at 212°F at standard atmospheric pressure. This unit is widely used in the US. The formula for converting to Celsius is °C = 5⁄9 (°F - 32°F).
- Failed Sensor Alarm:
This alarm is raised to indicate issues in the input sensor producing a valid signal. For example, thermocouple breaks, infrared problems, resistance temperature detector (RTD) open or short failures.
This is a numerical technique to simulate physical entities for a quick and optimal use of components in the design phase. It stands for Finite Element Method.
Fluorinated ethylene propylene. A fluorocarbon copolymer produced through free-radical polymerization of tetrafluoroethylene and hexafluoropropulene mixtures. It is different from polytetrafluoroethylene (PTFE) resins.
A tubular compression component, usually metallic, which is used for mounting a temperature sensing probe. It is used for air-tight fastening or sealing.
- Fiber, Insulation:
Insulation materials must be non-metallic and non-conductive. Fiber and most forms of plastic serve as safe insulation material around conductors and cables.
- Field of View:
Field of view: The spectrum of vision available for a human eye which is visible to the eyes or can be observed with the help of a device. For sensors, it is that till where the device or sensor can detect electromagnetic radiation.
A specific type of software that controls basic level hardware such as remote control for television. It can also offer a standard operating environment for a more complex software in a device. It is embedded in ROM, EPROM or Flash memory.
- Fixed point:
This is a standard degree of temperature used for calibrating thermometers or temperature measurement systems, such as boiling point of water.
The degree of ease with which bending and flexing movements of components such as a conductor can occur. Refer to “bend radius.”
- Flow Area:
The area in the cross section of conduit that enables free fluid flow through it.
- Flow Rate:
The rate of flow of liquid inside an area must be equal to that what flows out. It applies to liquids as they cannot be compressed. Flow rate is measured in cubic feet per minute, cubic meters per second or other units.
Refer to “Factory Mutual Research Corporation.”
- FNPT Informal:
Female (internal) National Pipe Thread.
- Form A:
It is a single-pole, single-throw relay that uses only the normally open (NO) and common contacts. These contacts open and close when the coil is charged and when the power source is switched off.
- Form A or C:
This is an electromechanical relay, which can function as Form A or Form C with the help of a jumper wire.
- Form B:
This is also a single-pole, single-throw relay, and functions like Form A using the NC and common contacts.
- Form C:
A single-pole, double-throw relay that uses NO and NC contacts.
Feet per minute is a unit of measuring speed. It is the number of linear feet travelled in one minute on a rotating component.
It stands for Feet per Second, and is a measure for velocity as well as speed. It is the distance travelled in feet divided by time in seconds.
- Freezing Point:
A fixed temperature point at which the given liquid is converted into a solid state. The freezing point of water is 0°C or 32°F.
The number of occurrences per a given unit of time, used to be measured in cycles per second. Now, it is measured in Hertz (Hz). The duration of one cycle is same, and this is a repetitive event. Hence, this period is called as the reciprocal of frequency.
It is a safety device that protects an electric circuit in case an overload occurs. It is a metal strip, which melts in case of excess current.
- Fuzzy Logic:
A type of computing logic closer to human brains that considers the binary 0 and 1 as two extremes but includes the numbers in between to find out the closes matching answer to a question, rather than using Boolean values such as true or false.
Although gain has many different meanings, in electronics, gain is the capacity of an amplifier circuit to increase the signal amplitude from the input to output port. It is expressed in decibels (dB). Gain may also refer to the P mode or proportional mode on the PID controller.
This is called glass-glass-silicone or glass to glass silicone. Silicone is a great sealant on glass.
- Giga (G):
An SI metric system unit indicating a factor of a billion or 109 (one billion in the US). It is expressed in units as G. However, it differs in Europe and the US. In the US a billion is one thousand million (1,000,000,000). In Europe, a billion is one million million (100,000,000,000) or trillion.
- Global Alarm:
It is the global digital output given by a controller or user interface.
It stands for Gallons per Hour. It is measuring unit indicating the volumetric flow rate of a fluid per hour.
It stands for Gallons per Minute. It is measuring unit indicating the volumetric flow rate of a fluid per minute.
- Green Rot:
It is the internal oxidation of alloys such as nickel-chromium-iron. It occurs when oxidizing and carburizing of metals happen at a time. The oxide precipitation gives the part a greenish tinge.
This is a reference point for an electrical circuit. Electrical circuits and exposed electrical parts are connected to the earth; it helps with better insulation and prevents shocks if touched by humans.
- Ground Loop:
Also called as earth loop, it is a situation wherein the two points in a circuit that are grounded have two different potentials. This happens due to the creation of several paths in the field, and leads to humming noise and disturbance.
- Grounded Potential:
Any circuit or chassis is considered to be at ground potential when it serves as a reference point for other type of potentials. This is basically the earth’s electrical potential.
- Grounded Junction:
This is a thermocouple probe or measuring junction which is formed through the welding of two thermocouple conductors.
Graphical User Interface. An easy-to-use interface on the computer which comprises icons and symbols for users to finish a process quickly. They do not have to write a long syntax on a command prompt.
This is a nickel-based thermocouple alloy with a composition of 95 percent nickel, two percent manganese, two percent aluminum, and one percent silicon. The alloy is used as the negative conductor of Type K thermocouple. HAI-KN® is the registered trademark of Harrison Alloys Company. Type K is an ASTM thermocouple.
A nickel-chromium based thermocouple alloy featuring 90 percent nickel and 10 percent chromium composition. This alloy is used in the positive conductor of Type K and E thermocouples. HAI-KP® is a registered trademark of Harrison Alloys Company. Type K and E are ASTM configurations.
This is a superalloy made of nickel, molybdenum, and chromium. It has a good corrosion resistance. Hastelloy® was developed by Haynes International.
It stands for high-density polyethylene plastics.
The constantly moving atoms and molecules in any matter vibrate and undergo friction, and this produce an energy called heat or thermal energy. Refer to “Btu,” “calorie” and “Joule.”
- Heat Transfer:
It is the transfer or flow of heat from an object of higher temperature to that of a lower temperature. This is according to the second law of thermodynamics.
- Heat Treating Thermocouple:
Refer to “thermocouple” and “heat treating.”
- Heat/cool output filter:
It is a filter that changes the response speed of the heat or cool output. The output responds to this change by attaining 2/3 its value. This value is achieved by number of scans set.
- Heated Insulation Concept:
Ceramic fiber heaters offer extremely high temperature heating. Here, the heating units are insulated with ceramic fiber, which isolates the heating chamber from the outer side
- Heat Sink:
Any metallic object that is fitted in a device to absorb and pull away the heat from the object and prevent excessive heating and maintain regular temperature.
- Hertz (Hz):
The unit for measuring frequency. It is expressed in cycles per second.
- High Deviation Alarm:
Rings an alarm bell if the deviation value in a given process is exceeds beyond the mentioned upper limit, due to any reason.
- High Process Alarm:
Rings an alarm bell if the set upper limit value is exceeded in process.
- High Process Variable:
Refer to “process variable.”
- High Reading:
There are pulse inputs and linear inputs. High reading implies a high input level that matches the high process value. Linear input high reading is expressed in percentage, while, pulse input high reading is expressed in cycles per second (Hertz, Hz).
- Hi-pot Test:
A test wherein high voltage is applied to a conductor to ensure the safety and quality of the insulation on it. Refer to “dielectric breakdown.”
- Hole Fit:
It is the gap between the cartridge heater sheath and the part on which it is being used. The heat transfer to the part is when the gap reduces.
- Hot Change:
This feature in band heaters facilitate individual heater replacement without dismantling or shutting down the entire system.
This feature in band heaters facilitate individual heater replacement without dismantling or shutting down the entire system.
It stands for Hypertext Transfer Protocol. The World Wide Web (WWW) follows this protocol to facilitate communication across the Internet and between servers and clients.
A shared point to connect individual nodes together to form a network (LAN), depending upon the configuration required.
A phenomenon wherein the process value fluctuates or oscillates near the set point.
A synthetically made rubber using chlorinated or sulfonated polyethylene. Hypalon® was developed by DuPont Performance Elastomers, and is its registered trademark.
This is also called switching differential. A controller switches off when the set point exceeds. It switches on if the process value drops below the set point.
I.D., which stands for Inside Diameter, also known as inner diameter or internal diameter. The internal diameter measures the inside of a hollow circular object.
- Ice Point:
Ice Point refers to the temperature at which the water changes from a liquid form to a solid form, i.e. 0°C (32°F).
- Idle Set Point:
The term refers to the desired control value after a timing period.
Internet Engineering Task Force, which is supervised by the Internet Society (an international, non-profit, membership organization), consists of a group of experts who are assigned to set engineering standards for the Internet technology. This group is managed by the Internet Society.
- IFC Heated Part Interference Fit Construction:
This is a manufactured part equipped with a specially designed groove, which is milled into it. There is an IFC heater element permanently formed into the groove for the purpose of making an intimate contact between the part and the element. IFC heated parts, which are an alternative to milled groove heaters and brazed heater assemblies, are commonly used for applications where cast aluminum is not fit for use or in situations where temperature is extremely high for aluminum “cast-in” heated parts.
This is basically a toggle-action information key on controllers. The purpose of this key is to offer context sensitive help in a display. I-key is usually colored as Pantone 293C or equivalent (highway information sign blue).
- Impedance (Z):
Impedance, which is measured in ohms, is the total opposition of a circuit to the flow of alternating current. In other words, it is a measure of the overall opposition of a circuit to current. It is calculated by including resistance and reactance.
Incoloy®alloys including 800, 800X and 825, are high-performance alloys that resist both oxidization and carbonization in high-temperature settings.
- Incoloy® 800:
This nickel- iron-chromium alloy is popular for its good corrosion and temperature resistance. Invented by the Special Metals Corporation Group of Companies, Incoloy® 800 is generally used for making heat exchangers and process piping, carburizing fixtures and retorts and furnace components among other high-temperature applications.
It is the family of austenitic nickel-chromium-based super-alloys that include the grades 600, 601, 625, and X750. Inconel®, which is a registered trademark (of Special Metals Corporation), has an incredibly high tolerance for extreme heat.
- Indication Accuracy:
Usually expressed as a + or -, indication accuracy is basically the closeness between a measured value and the displayed value.
Infrared is one of the many forms of electromagnetic radiation suitable for radiant heating and infrared (non-contact) temperature sensing. Infrared, which is a region of the electromagnetic spectrum, has unique wavelength that makes it invisible to the human eye.
- Initial Calibration Tolerance:
This is the allowable drift from the theoretical EMF value produced by a thermocouple type at a given temperature. See “limit of error.”
- Input Process:
The term refers to all of the materials and information that is supplied to the instrument to conduct a process.
- Input Scaling:
It is the ability to scale input readings to the engineering units of the process variable. Most often, these readings are in percent of full scale.
- Input Type:
Input type may refer to the various signal types that are connected to an input. A few amongst the several input types include thermocouple, RTD, linear or process.
- Installed Power:
Measured in kilowatt (KW), installed power is the sum of the nominal powers used for an application or process.
- Instrument Society of America (ISA):
The International Society of Automation, formerly known as The Instrumentation, Systems, and Automation Society, is a nonprofit organization that designs, develops, and maintains standards for measuring devices. These devices can be technical or scientific in nature.
A material that isolates a conductor from its surroundings. The material may isolate the conductor from heat, sound, or electricity. It is applied in sufficient thickness in order to achieve operational energy efficiency and expected performance.
- Insulation resistance:
Measurement of insulation resistance is quite important to determine the capacity of the insulation material to resist the flow of electrons through it. Expressed in ohms, measuring the same is imperative to prevent electric shocks and equipment damage.
It is the form of temperature control, which helps eliminate droop or offset, between set point and actual process temperature. See “automatic reset” and “reset”.
- Integral control (I):
It is defined as the ability to interchange components of system without affecting the accuracy.
It's a network address for computers that the Internet hosts use. IP address, which is short for Internet Protocol (IP) address, is a network layer protocol defined by the IETF. This identifying number for network hardware connected to a network enable users to perform an Internet speed test, IP address lookup, proxy detection, among others.
- IPTS48, 68:
IPTS stands for International Practical Temperature Scales. IPTS48, 68 indicates International Practical Temperature Scales of 1948 and 1968. These scales have been later replaced by ITS90.
The positive conductor in Type J thermocouples. The Type J thermocouple is an ASTM configuration.
ISA, which stands for the Instrument Society of America, is a nonprofit professional association that sets guidelines and standards to create a better world through automation. Today, it is known as the International Society of Automation.
- Isolation Junction:
This is basically a type of thermocouple probe construction. Widely known as ungrounded junction, its construction is characterized with a measuring junction, which is fully enclosed in a protective sheath and electrically isolated from it.
This is a term to indicate a sensor that is electrically separated from high-voltage circuitry. It allows the use of ungrounded or grounded sensing element.
Isothermal refers to a process in which a system changes, but the temperature is remains constant.
International Temperature Scale of 1990. Published by the Consultative Committee for Thermometry (CCT) of the International Committee for Weights and Measures (CIPM), this scale replaces both IPTS48 and 68. Adopted in late 1993, the standard scale made of fixed points that closely approximate thermodynamic temperatures.
It is the covering on a cable or wire. This outer covering offers electrical insulation and resistance from moisture, abrasion, chemicals, and other elements.
Stands for Joint Development Agreement, JDA is an agreement between two parties that specifies each party’s role and responsibility when working a development of the new product.
Also termed as a recipe, a job refers to a set of operating conditions for a particular process. This set of operating conditions can be stored and recalled in a controller’s memory.
- Joint Industrial Standards (JIS):
Stands for Joint Industrial Standards, JIS is a Japanese agency that is equivalent to Germany’s Deutsche Industrial Norm (DIN). The primary goal of the agency is to establish and maintain standards for components, as well as equipment. This is also termed as JISC (Japanese Industrial Standards Committee).
Joule is the universally accepted unit of heat energy. It is the work done by a 1N force to move an object by 1 meter in the direction of the force. This is also used to indicate the work required to create one watt of power in one second. It is also a work required to move a charge of 1 coulomb through 1 volt.
It is the point where two different metal conductors intersect to form a thermocouple.
It is an extremely lightweight organic polymer film developed in the late 1960s by the duPont de Nemours & Company. This versatile dielectric material offers an excellent balance of properties over a wide range of temperatures. It is widely chosen for its good dimensional stability, tensile strength, and low emission of gas in vacuums.
- Kelvin (k):
The kelvin (abbreviation K) is the Standard International (SI) unit of thermodynamic temperature on an absolute temperature scale. Zero Kelvin is absolute zero, or in other words the absence of all heat. This is perhaps the only temperature unit that uses no degree symbol (°). (0°C = 273.15K, 100°C = 373.15K).
- Kilo (k):
kilo is a unit prefix in the metric system denoting thousand.
- kilowatt (kW):
Kilowatt (symbol: kW) is a unit of electric power equal to 1,000 watts or energy consumption of 1000 joules for 1 second.
- Kilowatt hour (kWh):
The kilowatt-hour (symbolized kWh) is a unit of energy which equals to the energy provided by a thousand watts in one hour.
A thermocouple alloy that is highly demanded in the industry for the production of negative conductor of Type K thermocouples. It is a combination of 95 percent nickel, two percent aluminum, two percent manganese and one percent silicon. Alumel®, Nial® and HAI-KN® are the manufacturer trademarks for this nickel-based alloy. The Type K is ASTM configuration.
A thermocouple alloy, which is mostly used in the production of positive conductors of ASTM Type E and K thermocouples. Alloyed with 90 percent nickel and 10 percent chromium, the alloy’s trademarks include Chromel®, Tophel® and HAI-KP®.
The term Kilo-volt-amperes (kVA) is a measure of apparent power: Kilovoltampere is simply 1,000 volt amps and one unit of apparent power equals 1VA.
The k-value, (sometimes referred to as a k-factor or lambda value λ) is expressed in W/cmK (watt percentimeter Kelvin) or in Btu/hft.F (Btu per hour per ft. degree Fahrenheit). The k-value, which is the reciprocal of the R-value, thermal resistance, is the measure of a material's thermal conductivity coefficient. It also indicates the ability of the material to conduct thermal energy.
- Ladder logic:
Ladder diagram, better known as ladder logic, is an electrical circuit diagram in schematic style. Mainly used in developing programs or software for programmable logic controllers, it represents the positive and negative sides of the power input as the two main beams of a vertical ladder and connections between them as the rungs of the ladder.
Lag is a noticeable delay between two related parts of a system or process.
LAN stands for Local Area Network that spans a relatively small area. Designed to operate over a small physical area such as an office, factory or a group of buildings, LANs can be connected together in a Wide Area Network (WAN).
- Latent Heat of Fusion ((HF)):
Heat of fusion is the energy needed to transform a solid to a liquid without increasing the temperature. It is expressed in Joule/gram or Btu/lb.
- Latent Heat of Vaporization:
(HV) Heat of vaporization is the amount of heat energy needed to transform a liquid to a vapor without an increase in temperature. This is expressed in Btu/lb or Joule/gram.
- Lava Cone:
This is basically a low temperature silicate-based insulator. Lava Cone is usually used between electrically conductive and non-conductive casings or tubes.
Liquid Crystal Polymers (LCPs) are a class of aromatic polymers possessing a unique set of properties. This relatively unique class of partially crystalline high-temperature thermoplastic polymers have good impact strength.
Stands for Light Emitting Diode. LED is a semiconductor light source that emits visible light when an electric current passes through it.
It is one among several hot conductors found in an electrical circuit. In the US and Canada, single split phase, 240 V is equipped with two hot legs. However, three-phase systems will have three hot legs.
- Limit of error:
As defined by the ASTM specification MC96.1 (1982), this is a tolerance band of the thermal electric response of thermocouple wire. It is expressed as a percentage or a specific degree value in defined temperature ranges.
- Limit or limit controller:
A limit controller is used to monitor and limit the temperature of the process, or a point in the process. This highly reliable, discrete safety device can protect equipment and people as it interrupts power through the load circuit in case the temperature exceeds or falls below the limit set point. A limit controller must be rightly installed following the manufacturer’s installation guidelines using its own power supply, power lines, switch and sensor.
- Linear input:
It is an input function for which an electronic amplifier generates an output signal that represents a direct or straight line function. For such applications, the output is represented as output = input x gain.
Also called linearity error, linearity is a mathematical concept that has a profound impact on electronic design. This is a deviation of transducers and instruments from theoretical or expected straight line value.
- Linearization, input:
See “linearization” and “square root”.
- Linearization, square root:
Otherwise known as Square Root Extraction, linearization is a mathematical process, which is applied to extract a linear signal from a nonlinear signal corresponding to the measured flow from a flow transmitter.
- Liquid crystal display (LCD):
A liquid-crystal display (LCD) is a flat-panel display that is commonly used in laptop computer screen, TVs, cell phones and portable video games. LCDs, which are composed of several layers, are made of a material that changes reflectance or transmittance when an electrical field is applied to it.
It is the electrical demand of a process. The substance or an item may be heated or cooled using electricity. The load is expressed in current (amps), power (watts) or resistance (ohms).
- Local set point:
The target or primary set point value stored in a controller. Most controllers will at least one set point. There may be multiple set point values, too.
See “control loop”.
- Loop alarm:
This alarm system is an essential retail security product that encompasses high and low process, deviation band, and dead band. It also contains digital outputs, and auxiliary control outputs.
- Loop resistance:
When it comes to a thermocouple circuit, loop resistance refers to the total resistance of the conductors.
- Low deviation alarm:
Widely used as an alarm or control function, low deviation alarm warns if the process is below the set point by the low deviation value or move process variable. This is used as control or alarm function.
- Low Process Alarm:
This is a warning function that intimates when the process goes below the set value. This can also be used as alarm function or control function.
- Low reading:
An input level corresponding to the low process value. For linear inputs, the low reading is a percentage of the full scale input range. For pulse inputs, the low reading is expressed in cycles per second, Hertz (Hz).
- Ladder logic:
- Manual Mode:
A mode without automatic control. In this, the operator can manually set the output level.
- Manual Reset:
A limit control feature that requires a manual intervention to bring the limit to normal condition.
- Mass Flow Rate:
Often called the conservation of mass, is the mass or amount of substance passes through a unit at any given time.
A model of communication capable of controlling traffic on the network.
- Maximum Load Impedance:
Specified in ohms (symbol: Ω), the maximum power that can be transferred from source to load.
- Maximum Operating Temperature:
The maximum temperature at which a device is designed to operate for an extended period.
- Maximum Power Rating:
The maximum power that an equipment can withstand without hampering its operation.
MCDA is the abbreviation of Mutual Confidential Disclosure Agreement. It is a legal agreement where two parties agree upon terms of information sharing.
See relay, mercury displacement.
- Measuring Junction:
Often called hot junction, it is the thermocouple junction that is inserted into the material that is being measured.
- Mega (M):
A prefix unit means one million in the United States.
- Megawatt (MW):
A unit of power that is equivalent to one million watts.
- Melting Point:
The temperature at which substance starts melting.
A list of commands that needs to be performed by the operator.
- Mercury Displacement Relay (MDR):
It is a switching device in which plunger displaced mercury forms the electric circuit across contacts.
- Metal Fatigue:
A weakening of metal due to mechanical action or stress, resulting in small cracks. It shortens the thermocouple life.
- MI Leads:
Abbreviation of Mineral Insulated Leads. Lead wire assemblies can withstand high temperature up to 815°C and contamination such as gases, oil, solvents, moisture, and water. These adapters can be used in both standard industrial and cleanroom environments.
Management Information Base is a database type often associated with the Simple Network Management Protocol (SNMP) for managing the entities in the network.
A group of silicate minerals having basal cleavage. The material is primarily used as a heat and electrical insulator.
A unit of length that is equivalent to 0.0001 cm.
- Microvolt (µv):
An SI unit of electromotive force equivalent to 10−6 volts.
A derived unit of length that is equal to ¹⁄₁₀₀₀ of an inch.
- Milled Groove:
A groove that is machined to to accept a heater part.
- Milliampere (mA):
The SI base unit of electrical current. It is one thousandth of an ampere.
- Millivolt (Mv):
The millivolts (mV) is equal to the one-thousandth of a volt.
- Mineral Insulated Thermocouple:
A thermocouple probe featuring a thermocouple conductor inserted metal sheath, as well as dielectric material. The material is often mineral-based, and helps compact the size of the assembly.
- Minimum Load Current:
The smallest amount of load required for the power supply to operate safely.
- Minimum Output Impedance:
See off-state impedance.
This is Male National Pipe Thread.
- MO (Magnesium Oxide):
A type of magnesium mineral supplement that is chemically and physically stable at high temperature. The powdered chemical compound helps in improving the life of heaters.
- MModbus™ Protocol Driver:
It is a software program that converts OS instruction or programming language to the MODBUS™ protocol. These protocols easily integrate the information and sent it to a MODBUS™ device.
- Moisture Resistance:
The ability to resists the damaging action of water.
This alloy is made of nickel and copper sensor sheath, which exhibits excellent resistance to sulfuric and hydrochloric acid, seawater, hydrochloric acid, and more. This superalloy is the registered trademark of the Special Metals Corporation.
- Multilayer Hybrid:
A hybrid circuit made of alternative layers of insulators and conductors. Multilayer hybrid circuits can be made of gold, silver-palladium or copper conductors. It can easily combine dense packaging of electronics can easily remove generated heat.
A Terephtalate (polyester) film. It is the registered trademark of the E.I. duPont de Nemours & Company.
- Manual Mode:
- National Bureau of Standards (NBS):
Also called the National Institute of Standards Technology (NIST). It is a physical sciences laboratory, which promotes industrial competitiveness and innovations.
- National Electrical Code (NEC):
Also referred to as NFPA 70, in the United States and around the world, it sets standards for electrical safety in commercial, residential, and industrial occupancies.
- National Electrical Manufacturers Association (NEMA):
The largest US association that represents electrical equipment manufacturers that make reliable, safe, and efficient products.
- National Institute Of Standards And Technology (NIST):
Founded in 1901, NIST is a non-regulatory agency of the US Department of Commerce.
- National Pipe Thread (NPT):
It is also referred to as American National Standard Pipe Thread standards. It represents the technical standards for screw threads used in pipe fitting.
- Negative Temperature Coefficient:
In this, the electric resistance of the device decreases with the increase in temperature.
- NEMA 4X:
It is a NEMA specification that helps determine resistance to corrosion and moisture. This rating is important as it the user understand that the controller is corrosion resistant and washable.
Also known as pc-rubber or polychloroprene , this elastomer is produced from polymerization of chloroprene. It exhibits excellent chemical stability and maintains flexibility over a diverse temperature range.
It is the acronym for Network Basic Input Output System. It is not a networking protocol, but it offers services related to the session layer of the OSI model.
- Network Layer (OSI Layer 3):
This layer resides between the Transport and the Data link layerand it provides a data routing path for network communication. It is the third layer of the OSI model.
It is a thermocouple alloy made up of 95% nickel, 2% aluminum, 2% manganese and 1% silicon. It is used for making negative conductor for thermocouple K, which is an ASTM configuration. This alloy is a registered trademark of Carpenter Technology.
An austenitic nickel-chromium-silicon alloy that offers high thermoelectric stability in the air 1000°C (1830°F). It is used as a positive conductor of the ASTM Type N thermocouple.
An alloy of nickel and silicon that is made up of 95.6% nickel and 4.4% silicon. It can be used for the negative conductor of ASTM type N. This alloy cannot be exposed to sulfur-containing gases.
- No Key Reset:
This method easily clears the controller’s memory if any issue has occurred.
- Noble Metal Thermocouples:
These thermocouples have conductors made of platinum or platinum alloys. The ASTM Types B, S, and R, are noble metal thermcouples. They are suited for applications where they may encounter high temperature and corrosion.
A communication endpoint within a network that can send, receive, or forward information.
Theya re electrical signals that produce signal interference in sensors circuits or sensors.
- Noise Suppression:
that the electrical interference caused due to making or breaking of circuit or inductors is suppressed using various components.
It is a nylon compound with flame retardant properties, and is widely used for wire insulation. It is a registered trademark of of E.I. duPont de Nemours & Company.
Refer “National Pipe Thread”.
It is an abbreviation of National Sanitation Foundation or National Science Foundation.
A thermoplastic material that exhibits excellent abrasion and chemical resistance. The material is mainly used for insulation.
- National Bureau of Standards (NBS):
This refers to the outside diameter of pipe.
The difference between process set-point and the actual temperature is known as offset. In a stable thermal system, some controllers introduce an offset variable to compensate for sensor placement. It is the synonym of droop.
- Offstate Impedance:
It is the low resistance of output devices in the off-state. This is based on the frequency of internal or external noise suppression devices used, and load supply current of the device.
It is the abbreviation of a group Oxygen-free high thermal conductivity copper. A group of high conductivity copper that reduces the level of oxygen to .001% and below. This is the pure copper used in ASTM Type T thermocouple.
- Ohm (Ω):
A standard unit of electrical resistance. One ohm is equal to a volt per ampere.
- Ohm’s Law:
The law that states that current flow to the circuit is inversely proportional to its voltage.
An object identifier is a mechanism by International Telecommunication Union and ISO/IEC for naming any object with a globally persistent name.
A closed-loop control method that can be on until set-point is reached, and then can be off until the process exceeds the state.
- On-Off Controller:
Also known as a feedback controller, which operates in either full-off or full-on state.
- Open Loop:
A non-feedback control system, in which the control actions are being controlled by process variables. The system of this type do not have a sensory feedback.
- Operator Menus:
In this, the operator can change various control features, as well as actions from the front panel of the controller.
- Optical Isolation:
It refers to two electronic networks that are connected through a photoelectric receiver and LED. Typically, there are no electrical continuity between these circuits.
The Federal Occupational Safety and Health Administration (OSHA) ensures safe and healthy or healthful working conditions for working women and men by setting standards, as well as, by providing education, training, outreach, and assistance.
- OSI Reference Model:
Open System Interconnection (OSI) model is defined as a conceptual model that describes how different applications communicate over a network. The communication between two endpoints is divided into seven different layers, which each include multiple protocols, standards, and other types of services.
The desired value of the process variable.
- Output Type:
It is the form of PID control output, such as serial digital to analog converter, time proportioning, distributed zero crossing, and so on. It may also refer to the electrical hardware the sends an output.
It refers to an output exceeding the set-point before it stabilizes.
- P Control:
A proportional control applied to a measured or controlled variable which is proportional to the difference between the measured and desired value.
- Panel Lock:
They are used to prevent the operation of the front panel.
- Parallel Circuit:
When all devices are connected using parallel connections, then the circuit is referred to as a parallel circuit. All the components share the same voltage with the current divide as per their resistances.
It is defined as a constant value of the application or a measurable values of an electronic controller to given inputs.
It is a non-electrolytic finishing process, which removes free irons from the surface of stainless steel and makes it more rust-resistant.
- Passive Component:
A component that does not require any electrical power to operate, but it can store energy and dissipate it. A typical passive component would be an inductor, capacitors, and resistors.
See polycarbonate, a clear plastic used to make lightweight lenses, shatterproof and such.
- PD Control:
PD control combines proportional and derivative control in parallel.
- PDR Control:
The PDR mechanism used in the fast responding system where the reset instability issue can be caused. It allows an operator to enter manual reset values that eliminate droop in the system
Polyetherimide (PEI) is a versatile and reliable thermoplastic characterized by high heat resistance and great electrical properties that remains stable over diverse temperatures and frequencies.
- Peltier Effect:
It the effect in which heat is observed or given when an electric current is maintained at the junctions between the two materials.
- Percent Power Control:
An open-loop control system in which the output is neither measured nor fed for comparison with inputs.
- Percent Power Limit:
The output current is restricted to a predetermined level.
Also abbreviated PETE, polyethylene terephthalate is a chemically stable polyester that is used for making fibers, clothing and beverage containers.
A co-polymer product of PTFE.
It is described as the position of a point on the alternating current cycle. Similarly, if the phase is described in degrees, then it will increase by 360˚ as increase by one periodic cycle.
- Phase-angle firing:
Referred to as zero-cross firing, it is a mode of power control in SCR switches.
- Physical Layer (OSI Layer 1):
First and the lowest layer of OSI model, which deals with the physical connectivity of two different stations. The layer resides below the Data Link Layer.
- PI Control:
Proportioning Control with automatic reset option. Output power is equivalent to the sum of proportion and integration coefficients.
- PID Controller:
Referred to as three-term controller (proportional, integral and derivative controller), a control loop feedback mechanism calculates an error value as the difference between a set point and process variable and applies a correction based on PID respectively.
The ping command stands for packet internet or inter-network groper that verifies, if an IP address available and that it can accept the request or not.
A synthetic material that flows under heat or pressure to mold into different solid objects. They are simply chain of molecules that joined or lined together.
Platinel® is a rademark of Englehard Industries. Thermocouple made from a nonstandard platinum alloy can measure temperatures above 800°c. These thermocouples are mainly used for measuring the temperature of gas streams in gas-turbine engines.
- Platinum (Pt 2):
A noble metal with an excellent chemical and heat resistant characteristics. It is used as a negative conductor in ASTM types S and R thermocouples.
- Platinum 10 percent rhodium:
The platinum-rhodium thermocouple alloy used to form the positive conductor on ASTM type S thermocouples.
- Platinum 13 percent rhodium:
The platinum-rhodium thermocouple alloy forms the positive conductor on ASTM type R thermocouples. These thermocouples are suited for use at up to 0°C.to 1600°C.
- Platinum 30 percent rhodium:
It forms positive conductor on ASTM B thermocouple, which produces the same output at 0 °C and 42 °C.
- Platinum 6 percent rhodium:
A platinum-rhodium thermocouple alloy forms negative conductor on ASTM type B thermocouples.
- Platinum 67:
An NIST platinum standard is a great replacement of platinum 27. Incorporates the temperature range between 630.74 and 1064.43°C.
It is the state of condition having two opposite poles or aspects, such as positive and negative. It determines the direction of current flow. A water molecule is a great example of polarity.
- Poll Engine:
The component continuously request data from devices connected on a network.
- Polycarbonate (PC):
A naturally transparent amorphous thermoplastics that are useful when transparency and impact resistance are product requirement. Owing to their high strength and toughness, they are used for plastic lenses in eyewear, automotive components, light fixtures, etc.
Referred to as long-chain polymers, it can withstand a good deal of wear and tear. Classified as saturated and unsaturated polyesters.
- Polyetherimide (PEI):
With excellent thermal, mechanical, and electrical properties, a versatile thermoplastic is widely used in high-performance applications like aerospace, industrial, automotive, and more.
- Polyethylene (PE):
Polyethylene or polythene (abbreviated PE) is a durable thermoplastic with a variable crystalline structure. Made from the polymerization of ethylene, they are used in a wide range of applications such as films, laminates, tubes, etc.
A large molecules composed of repeated subunits.
- Polyphenylene sulfide (PPS):
A semi-crystalline, high-temperature thermoplastic possesses self-extinguishing properties without any flame retardant chemical additives. It has a high melting point of approximately 280°C.
Abbreviated as PP, polypropylene is also known as polypropene. It is slightly harder and more heat resistant.
- Polysulfone (PSU):
A replacement for polycarbonates, these polymers are known for their stability and toughness at high temperatures.
- Polyurethane (PUR):
A large family of polymers, they may be thermoplastic or thermosetting, flexible and soft or rigid and hard with great property variances.
- Polyvinyl Chloride (PVC):
Naturally white and brittle plastic with excellent flexibility, and dielectric strength.
- Positive Temperature Coefficient (PTC):
A positive temperature coefficient describes that its resistance increases with increase in temperature.
A process of filling electronic assembly with a sticky compound for the exclusion of contaminants and moisture.
- Power Factor:
The power factor is equivalent to the real power in watts divided by apparent power in volt-ampere.
- Power Loss Alarm:
Also called as a power failure alarm, it is a power monitoring device that recognizes the outage of power as a limit condition.
A thermocouple is exposed to application conditions. A pre-aged thermocouple can offer consistent or reliable readings.
- Preferential oxidation:
Abbreviated as PROX, a phenomenon in which limited oxygen reacts with active chromium in the conductor alloy. It is known as the preferential oxidation of gas on a catalyst. A catalyst is a process in which a substance can be used to increase the chemical reaction rate.
- Presentation Layer:
It is the sixth layer of the OSI model of computer networking, serves data to the application layer in a standard format.
- Primary Standard:
A device that meets the International Temperature Scale of 1990 (shortened as ITS-90) conditions.
A temperature detection device that itself monitors the ambient temperature. It may contain a RTD, integrated circuit sensor, a thermocouple, etc.
- Process Alarm:
An alarm that triggers when the process value deviates from a fix set point.
- Process Error:
It is a ratio of the actual process value and the set point.
- Process Variable:
It is the process parameter or process value that is being measured. Flow, temperature and pressure are well-known examples of process variables.
- Programmed Display Data:
A process of visualizing the process information, such as the intended alarm limit, set point corresponding to temperature or other engineering units.
A symbol that enables the user to enter text or input.
A condition in which output related to the error from a set point.
- Proportional Band:
It is also referred to as bandwidth, and it is a range where proportioning function of the PID control is active.
- Proportional Control:
A control system that measures the difference between the process value and the desired value.
- Protection Head:
Equipment that protects sensors probes or heaters against impact and burns injuries.
- Protection Tube:
A tube that protects sensors especially RTDs, thermocouple against process conditions or mechanical damage.
It stands for pound per square inch. A common unit of pressure used in diverse pressure measuring applications.
It is known as gauge pressure, which is measured relative to ambient pressure. The ambient pressure at sea level is 14.7 PSIA, however ambient PSIG is always zero.
Abbreviation for Polytetrafluoroethylene, it is soft fluoropolymer with an extremely low coefficient of friction. It also has excellent weathering and chemical resistance.
- Pulse Input:
A module that receives signals in electronic form, counts them and passes the value to the processor for further processing. A great example is encoders.
- P Control:
In thermodynamics, the term is used to indicate the mass fraction of vapor in a saturated mixture of vapor. The quality of saturated vapor is 100 percent and quality of the saturated liquid is 0 percent.
It is the energy emitted in the form of particles or waves. Refer to “infrared” or “emissivity”.
- Radio frequency interference (RFI):
The conduction of radio frequency energy that produces noise in an electrical device. This noise interferes with the function of the device that is lying adjacent. RFI is mainly induced by electromagnetic waves between the frequencies of 10 kHz and 300 GHz. These frequencies can affect systems when conducted through power input lines or sensors.
It is an increase in the temperature of a system. This increase is brought through programming.
The area between two limits, where the values are measured. This is usually measured in the range of upper and lower limits.
An anticipatory action based on the rate of change of temperature. The action compensates to minimize undershoot and overshoot. Refer to “derivative”.
- Rate Band:
A range in which the controller is active. This is expressed in multiples of the proportional band. Refer to “PID”.
It is a method used by a controller to measure the flow of an uncontrolled variable. The controller uses a fraction of this variable to control the flow of the next variable.
Refer to “job”.
- Reference Junction:
It is the temperature point where a thermocouple connects to a temperature controller or temperature measurement instrument. Some devices will introduce a compensation value to the signal to prevent an error from occurring. This is also known as a cold junction.
- Reflection Compensation Mode:
An automatic control feature in a sensor that helps correct its reading.
- Reflective Energy:
The energy produced in the background when an infrared sensor is used to measure the radiant energy of an object. This energy may influence the readings by causing an error.
- Refractory Metal Thermocouple:
The thermocouple made of materials including rhenium and tungsten. These thermocouples have melting points above 3515°F (1935°C). Types G, D, and C are refractory metal thermocouples, and they are not ASTM configuration.
- Relative Thermal Index (RTI):
A thermal classification test conducted by the Underwriter’s Laboratories (UL®) to compare the performance of new material with the performance of another known material. In this test, at least two materials are used.
An electrical device that is activated by a signal or current in one open circuit to close or open another circuit. These devices are equipped with electromagnets.
A controller that is guided by another device for set point signal. The controller receives signal from the device called master.
- Remote Set Point (RSP):
A device that receives a signal from another device for the set point is called RSP. The typical applications of RSP are master & slave applications, multi-zone set points, and on cascade control slaves.
It is an ability of a conducting device to provide the same reading under identical conditions. Refer to “stability”.
A control action that eliminates droop or offset, between the set and the actual process. This control action is initiated automatically. Refer to “integral”.
- Reset Windup inhibit:
Refer to “anti-reset wind-up”.
The measure of opposition to the flow of current in an electrical circuit. It is measured in ohms.
- Resistance Temperature Characteristic:
The change observed in the sensor resistance, in response to the change in temperature. Refer to “negative temperature coefficient” and “positive temperature coefficient”.
- Resistance Temperature Detector (RTD):
These are the sensors used for temperature measurement. RTDs are being used in temperature measurements for industrial applications below 600°C. There are two types of RTDs – the wire RTD and the thermistor. The wire RTD is made of platinum, whereas the thermistor is made of a semiconductor.
- Resistive Loads:
The term for loads that may alter the flow of electric current by limiting it. In the case of pure resistive loads, current and voltage are always in phase.
It is the expression of the smallest input change unit that can be easily identified at the system output.
- Response Time:
1) It is the time needed for a sensor to achieve 63.2 percent of a temperature step change in specific conditions. The sensor requires five time constants to stabilize at 100 percent of its step change value. 2) It is the time needed for an infrared temperature sensor to reach 95 percent of a step change value. The infrared sensor requires three time constant to stabilize at 100 percent of its step change value. The system response time is the sum of the constants of components.
- Retransmit Output:
An output signal, which can be scaled to represent the set point value or the process value. This is only possible with analog signals.
- Reverse Action:
An output control action that is a reverse of the input action. For instance, the increase in the process variable will bring a decrease in the output. Heating is the best example of reverse action.
Refer to “Radio frequency interference”.
A silvery-gray metal, which is one of the rarest elements found in the earth’s crust. When combined with tungsten, the metal forms an alloy with a better temperature strength than tungsten.
- Rhodium (Rh):
It is a silvery-white and chemically inert transition metal in the platinum group. When mixed with pure platinum, this metal produces an alloy that has a better temperature strength than pure platinum.
A networking device that enables data exchange between different computer networks such as from one computer local area network (LAN) to another using Internet Control Message Protocol (ICMP), part of IP (Internet Protocol).
Refer to “Resistance Temperature Detector”.
Refer to “Relative Thermal Index”.
- Rubber Insulation:
A designation for thermosetting elastomers, which are used for insulating wire conductors used in the refrigeration and HVAC industry. The insulation aids in condensation control owing to its excellent thermal conductivity and moisture resistance. Examples of these thermosetting elastomers include synthetic and natural rubbers, neoprene, and butyl rubber.
It stands for the Society of Automotive Engineers.
- Safety limit:
Upper and lower limits set by manufacturers, as well as industrial regulation bodies to prevent machines and equipment from crossing the set limits such as of temperature and pressure. This helps prevent risk and safety issues such as fire in applications.
It stands for “Scientific Apparatus Makers Association.” This association sets standards for elements such as nickel, copper, and platinum resistance elements, which are widely used as thermocouple elements.
- Saturation Pressure:
The maximum possible pressure on a liquid applied by vapor, which is in equilibrium with the liquid, at a given temperature. So, the liquid and vapor can coexist.
- Saturation Temperature:
This is basically a boiling point of liquid. This is the temperature at which liquid becomes a vapor.
It is a standard volumetric flow rate. This is the flow rate of vapors and gases under standard atmospheric pressure and temperature. It is expressed in cubic feet per minute.
- Screen printing:
It is a printing method that comprises the application of ink onto the surface. The image is photographically transferred on a fine screen. The areas which are not printed are blocked.
- Secondary standard:
They are measurement tools calibrated in reference to the primary standard.
- Seebeck coefficient:
Seebeck coefficient is expressed in volts or microvolts per Kelvin. It is the measure of change in magnitude of applied thermoelectric voltage with reference to the difference in the temperature throughout the material.
- Seebeck effect:
It is a phenomenon when the temperature difference between two dissimilar metals produces potential difference between the two objects in a circuit.
- Seebeck EMF:
It stands for Seebeck electromotive force. It is the net thermal electromotive force (EMF) in a thermocouple when there is no current flowing.
Typically, any metal such as germanium and silicon that has properties of conductivity and insulation. It finds a wide application in electronics.
- Serial Semiconductor:
It is data transfer done one bit at a time across a single communication channel.
- Series circuit:
It is a circuit wherein the resistors are arranged in a sequence so that the current has only one channel to flow through and is uniform in each resistor.
In a client-server network, one computer is the server and other connected to it are the clients. This means it stores the data of all the client computers and offers functionalities to them.
Metallic or nonmetallic filaments or fibers are woven around a wire conductor to produce electrical insulation and increase abrasion resistance. Refer to “braid.”
- Session Layer:
This is the fifth layer of the OSI model that starts, stops and manages connections between applications. The Session Layer resides between the Presentation Layer and the Transport Layer.
- Set point:
The set or required value such as the pressure or temperature to be maintained for a particular system, which is fed into a controller.
- Set pot:
The set temperature or any parameter programmed in a controller may need to be adjusted; this is done with the help of a potentiometer, and is called set pot.
- Setting accuracy:
It is a very close or matching value given by an input device that matches with the required or estimated value. It is expressed as a percentage.
It stands for “standard flow velocity in feet per minute”, and is used to calculate gas flow.
- Shape factor:
It is the value depending on the shape of an object, regardless of its dimensions. In terms of thermal energy, it is the amount of radiation that leaves one surface and strikes another.
- Sheath thermocouple:
It is a cost-effective and corrosion-resistant sheath material which is made from hard metals such as stainless steel. It has mineral insulation.
It is a layer of metallic foil or braided wire over a conductor that shields or prevents electromagnetic interference from external entities and keeps the inside material safe.
- Shield coverage:
Refer to “shield percentage.”
- Shield effectiveness:
It is the relative ability of a shield material to sense and prevent electromagnetic interference.
- Shield percentage:
The amount of area of a circuit or wire covered by a shielding material, and is expressed as a percentage.
Shunting implies changing the current path. In terms of an electrical circuit, shunt is a device that creates a low-resistance, alternate path for the current to flow. A sensor signal can shunt in case the set temperature exceeds and the dielectric material loses its resistance. This can lead to wrong readings.
This stands for Systems International. This system of standard metric units is recognized in most countries across the globe.
A signal is an impulse in the form of current that transfers information from one end to the other, in a circuit or device.
A tetravalent non-metallic good conductor chemical, which is widely used in electronics.
- Silicon controlled rectifier (SCR):
It is a four-layered solid-state device or thyristor, which controls the current. It is used in electronic devices for voltage and current control.
Also called polysiloxanes, silicon is a polymer made of alternate chains of silicon and oxygen atoms, sometimes combined with other elements to achieve required properties such as heat resistance.
- Silicone rubber:
This is a silicone elastomer available in several formulations. It is flexible and has a high tensile strength, and hence has several industrial and domestic applications.
- Slidewire feedback:
It is a process that helps control the position of a valve using a potentiometer. The position of the valve is indicated by resistance.
It stands for Simple Mail Transfer Protocol, and is a protocol that enables e-mail servers to function sending and receiving emails.
This stands for Simple Network Management Protocol. It is an IP to detect and monitor network devices and fix network issues.
- SNMP agent:
This works as a network administrator, and is a software that responds to database queries and provides information or statistical data.
- SNMP manager:
This is an application software that manages the SNMP agents in a network. It communicated with the SNMP agents and devices.
In heat treating processes, objects are immersed in a hot environment, at the specified temperature to undergo the required metallurgical change.
- Society of Automotive Engineers (SAE):
It is a non-profit organization which facilitates education and scientific research pertaining to various automobiles, transportation systems, road equipment, marine, railway, and aviation systems.
- Soft start:
It is a process of turning on electronic devices in a gradual manner to avoid excess stress on the components and sudden voltage surges.
It is a virtual program that the hardware of a computer system uses to function. A program is a set of instructions or code to perform a particular task.
- Solid-state relay (SSR):
It is an electronic switching device designed to switch AC and DC currents with the help of a switching transistor. It switches on or off when voltage is applied externally on its terminals.
It is the difference or the normal range in the defined upper and lower limits such as maximum and minimum pressure or temperature.
- Spark test:
This is a test performed to detect insulation defects in wires and cables to check their safety and quality. It is a high-voltage, low-amperage test.
- Specific gravity:
(sp. gr.) The relative density of a given substance with reference to another substance, especially water. Refer to “density.”
- Specific heat capacity:
This is the amount of heat required to raise the temperature of one kilogram (or pound) of substance through 1 Kelvin. It is usually expressed in joules. In most materials, and varies based on material, its state, and temperature.
- Specific volume:
In thermodynamics, it is the ratio of volume to mass in a given substance. It is inversely proportional to density, and expressed in units of cubic meters per kilogram.
- Spectral filter:
It is a filter that restricts the electromagnetic spectrum to a certain bandwidth, and helps select or delete information from the image, on the basis of the wavelength.
- Spectral response band:
The infrared spectral band is divided into five regions based on the wavelength, such as long and short wavelengths. This finds application in electronics infrared sensing and imaging equipment. High wavelengths correspond with higher temperatures, which means hot areas shine bright.
- Spot size:
Refer to “field of view.”
This is the difference between the heating and cooling temperatures, in relevant applications. It is also known as process dead band, which is the neutral or dead zone with no output.
Refer to “solid state relay.”
This is a state of a system or entity where the input, process, and output are constant and at a set speed.
A set value or reference point from which measurements or calibrations are made.
- Standard wire error:
This expression shows how much an object or device can deviate from the set or defined standards, and it is also known as standard tolerances. It is expressed in terms of ±°C or percentage.
This is a part of a large network such as Internet or LAN. It follows the same TCP/IP protocol and shares the same IP address prefix. This division of networks help increase their security and performance.
This is a process wherein a liquid is heated beyond its boiling point. It is heated to the point where vapor bubbles disappear.
- Surge current:
When capacitive-, inductive- or temperature-dependent resistive loads such as tungsten or silicon carbide heating elements are initially connected to a power source, there is a rush of current for a few cycles, and then it subsides.
Swaging is a uniform compaction or a forging process that alters the dimensions of the given object by using dies. This improves the dielectric strength and thermal conductivity of the object.
A switch has multiple meanings depending upon the context. Primarily, it is an electromechanical device used to switch off or on an electrical circuit. It is also a network routing device that serves as a node for each connected device.
- Switching differential:
Refer to “Hysteresis”
- Switching sensitivity:
The temperature change required in on-off control to change the output from fully on to fully off. Refer to “hysteresis.”
Transmission Control Protocol. It is one of the two primary protocols that helps two or more hosts establish a connection and exchange information. TCP is a session-based transport layer protocol defined by the IETF.
Transmission Control Protocol/Internet Protocol. It is one of the primary protocols used for establishing connection and data exchange.
It stands for timed derivative, which is a derivative function.
Also known as polytetrafluoroethylene (PTFE), it is a synthetic fluoropolymer of tetrafluoroethylene. This is the registered trademark of Du Pont.
Ehtylene-tetrafluoroethylene (ETFE) is a fluoropolymer material which is chemically inert and has excellent mechanical properties. This has numerous applications across industries where strong plastic is required. It finds applications in the cable and wire industry. Tefzel® is a registered trademark of Du Pont.
- Telecommunication Industry Association (TIA):
It is a trade group that sets standards for thethe telecommunication industry. It is accredited by the American National Standards Institute (ANSI).
- Temperature calibration point:
The temperature at which the output of a sensor or a given device is compared against a standard to see if it matches.
- Temperature limit switch:
This is basically a long temperature sensor probe, which senses temperatures in say furnaces. If the temperature inside the furnace exceeds its set limit, this switch helps the burners shut down instantly.
- Temperature ambient:
Ambient temperature is the room or air temperature in a given area that surrounds the components of a thermal or computing system. This temperature is essential for the performance of the given system or component.
- Tera (T):
This is metric system unit prefix denoted by 1012, and considered as one trillion in the US
This is widely used short hand abbreviation for PTFE, polytetrafluoroethylene, or Teflon®.
- Thermal conductivity:
It is primarily the ability of the given material to produce heat. This differs with the type of material; for instance, most metals have a high thermal conductivity. This is expressed in Btu/hr-ft-°F or Watts/meter-°C.
- Thermal EMF:
The ability of a thermocouple to produce a voltage that increases or decreases in proportion to its change in temperature.
- Thermal expansion:
This is the increase in the size of a material due to an increase in temperature, in terms of shape, area, and volume. This happens because of the increased molecular vibration.
- Thermal gradient:
This is a measuring quantity that states the direction of the temperature and the rate at which it changes, at a particular location.
- Thermal lag:
The temperature of an object varies with regards to its thermal mass and in accordance with the outside temperature. A material with a high thermal mass will show a high thermal lag as it takes time to absorb the surrounding temperature.
- Thermal shunt:
In this scenario, the mass of the sensor or component absorbs a portion of the heat being measured, and this may result in a wrong reading.
- Thermal system:
This is system with a regulated environment that consists of a heat source, heat transfer medium or load, sensing device, and a control instrument.
This is a type of resistor which exhibits a large change in resistance for a small change in temperature. Thermistors usually have negative temperature coefficients, although they are also available with positive temperature coefficients.
- Thermocouple (T/C):
This is a temperature sensing device made by joining two dissimilar metals which form electrical junctions at different temperatures. This produces voltage in proportion to the temperature difference between the hot and cold junctions.
- Thermocouple aging or aging range:
Thermocouples are widely used in furnace applications. Over a period of time and due to withstanding extreme high temperatures, the thermoelectric coefficients of their wires drop. This impact voltage measurement. Different thermocouple types in different applications age differently depending on the conditions.
- Thermocouple break protection:
This is the ability of a control to detect a break in the thermocouple circuit and take an action accordingly.
- Thermocouple extension wire:
The thermocouple extension wire connects a thermocouple probe to the instrument which reads data.
- Thermocouple junction:
The point where the two dissimilar metal conductors join. Typically, there are two junctions, one for measuring and the other as a reference. Refer to “junction,” “measuring junction” and “reference junction.”
- Thermocouple pre-aging:
Refer to “pre-aging.”
- Thermocouple type:
There are about eight types of thermocouples: J, K, T, N, E, B, R, and S. Types J and K are the most widely used ones. The thermocouples B, E, J, K, N, R, S, and T are ASTM types and D, G, C are non-ASTM types.
- Thermocouple, heat treating:
A thermocouple suitable for the given temperature range and atmosphere is used in heat treating of metals. It strengthens or softens the metal depending upon the requirement.
This is a set of thermocouples which convert thermal energy into electrical energy, and measure small amount of radiant heat. Thermopiles are usually used in infrared detectors in radiation pyrometry.
- Thermopolymer technology:
Thermopolymer or thermoplastic is a process in which plastic heated to become moldable and soft. It solidifies upon cooling.
This is a type of plastic, which cross links during the curing process. This forms a sturdy and irreversible bond, so, if it is reheated, it does not melt.
This is a cylindrical tube with a closed end designed to protect temperature sensors from harsh outside environments. Refer to “protection tube.”
- Thomson Effect:
Heat is generated or absorbed, when current passes through a circuit with varying temperatures along its length.
- Three-mode control:
A PID controller has a three-mode control, which is proportional, integral (reset), and derivative (rate). Refer to “PID.”
This stands for “integral term”.
Refer to “Telecommunications Industry Association.”
- Time proportioning control:
In this method, on-time of a device is proportionated with off-time within a fixed timeframe, to achieve a proportional response. This variance is proportional to the difference between the set point and the actual process temperature.
This is a thermocouple alloy that is made of 90% nickel and 10% chromium. It is used in the positive conductors of ASTM Type E and K thermocouples, and was developed by Carpenter Technology.
This is a device that converts physical parameters such as pressure, temperature, and brightness into electrical signals, and reconvert them as well.
This is a spike in an electric current that lasts for a short while. Transients may damage or interfere with the operations of electronic temperature and power controllers.
This is a device that transmits data from either a thermocouple or a resistance temperature detector (RTD) through a two-wire loop which is supplied electric current externally. The transmitter acts as a variable resistor with respect to its input signal.
- Transport Layer:
This is the fourth layer of the seven-layer OSI (Open System Interconnection) protocol model that is responsible for data transfer, flow control, and error recovery between communicating hosts.
It is a solid-state device that switches alternating current.
The science or study of surface friction or lubrication. It considers two interactings surfaces in relative motion.
- Triple point:
A thermodynamic state in which the gas, liquid and solid phases all occur in equilibrium. For water, the triple point is 0.01°C, at standard atmospheric pressure.
- Tungsten (W):
This is a metal which exists in solid state at room temperature, and is used as a positive conductor in some types of thermocouples made of tungsten/tungsten 26% rhenium (W/W26Re).
- Tungsten 25 percent rhenium:
This is a thermocouple alloy which works as a negative conductor in some types of thermocouples made of tungsten 3% percent rhenium/tungsten 25 percent rhenium thermocouple (W3Re/W25Re).
- Tungsten 26 percent rhenium:
This thermocouple alloy works as a negative conductor in some thermocouples made of tungsten/tungsten 26 percent rhenium (W/W26Re) and tungsten 5 percent/tungsten 26 percent rhenium (W5Re/W26Re).
- Tungsten 3 percent rhenium:
This thermocouple alloy works as a positive conductor in some thermocouples, made of tungsten 3 percent rhenium/tungsten 25 percent rhenium (W3Re/W25Re).
- Tungsten 5 percent rhenium:
This thermocouple alloy works as a positive conductor some thermocouples. It is made of tungsten 26 percent rhenium (W5Re/W26Re).
- Tungsten lamp:
Tungsten filament is used in old lighting systems such as the standard incandescent light bulbs, and it is surrounded by an inert gas or a vacuum. Tungsten has a 16:1 hot to cold resistance ratio.
An end-to-end project which offers erection, commissioning and maintenance services.
- Twisted pair:
This is a normal pair copper wires twisted around each other. They are used by telecom companies to connect telephones across. The twisting reduces noise and crosstalk.
UDP (User Datagram Protocol) is a communications protocol that is used as an alternative to TCP. It runs on the top of IP networks as UDP/IP. More efficient in terms of both latency and bandwidth, UDP is widely used in video conferencing and real-time computer games. This sessionless transport layer protocol, which is defined by the IETF, is the simplest protocol available of the TCP/IP protocol suite. Hosts can broadcast messages via UDP/IP without establishing connections with the receivers.
UL which stands for Underwriters Laboratories, is the registered trademark that encompasses UL's extensive safety research and scientific expertise. It is an independent testing laboratory that establishes commercial and industrial standards, and tests products to ensure their safety standards.
The band of the electromagnetic spectrum that is situated beyond the visible spectrum at its violet end. This spectrum lies in the wavelength of 10 nm to 400nm, which is shorter than visible light.
The amount by which a process variable falls below the set point before it stabilizes.
- Ungrounded Junction:
See “isolated junction”.
Uninsulated means without thermal and electrical insulation using nonconducting material to prevent the transmission of electricity, heat, or sound.
Pipe union is a type of fitting equipment that helps joins extension pipes. It also helps disjoint two pipes very easily without regard to their thread orientation.
- Upscale break protection:
It is a kind of break detection that helps detect burned-out thermocouple by giving signal to the operator regarding the burn out on time.
USB, short for Universal Serial Bus, is a standard type of connection that helps to connect at least 127 peripheral devices to computers. It allows a computer to communicate with peripheral and other devices like printers, scanners, keyboards, mice and digital cameras.
- Vacuum Braze:
Vacuum brazing is a high-end joining technology that helps join metals or alloys by melting a filler metal, or the brazing alloy in the absence of atmosphere. The process is usually done in a vacuum chamber or furnace.
This is the quantitative measure of a variable or a signal.
Abbreviation for Verband Deutscher Elektrotechniler, VDE is one of the largest technical-scientific associations in Europe, with 36,000 members concerned with the safety of electrical products. Being an integral part of the development of key technologies in electrical engineering, information technology and consumer protection, VDE is the established standard for innovation and safety.
As simply defined, viscosity is a measure of a fluid's resistance to sheering forces (flow). Fluid Viscosity, sometimes referred to as dynamic viscosity or absolute viscosity is usually denoted by the Greek symbol μ (mu). With increasing temperatures, viscosity of fluids decreases. When described in terms of a fluid's thickness, high viscosity indicates a tendency for a fluid to flow or move slowly.
Volatile organic compounds (VOCs) are low-molecular-weight organic compounds that are easily released from burning gasoline or coal to solvents, glues, dry-cleaning products, among others. VOCs get easily evaporate, which in turn contributes to air pollution and serious health conditions.
- Volt (V):
Voltage, also called electromotive force, is one of the significant parameters associated with any electrical or electronic circuit. Voltage, which can be can be direct or alternating, is expressed in volts. One volt (V) is equal to one ampere of current (I) flowing through one ohm of resistance (R), or V = IR.
- Volt Amperes (VA):
A measurement of apparent power consumed by an electrical circuit or measure of power in a direct current (DC) electrical circuit In VA, V stands for volts and I stands for current in amperes.
- Vacuum Braze:
- Watt (W):
It is the unit of power, which is equivalent to one joule per second. The watt (abbreviated W) is used to indicate the rate of energy transfer. Also, it can be defined as the current flow of one ampere with a voltage of one volt. The symbolic representation of the watt (W) is as follows:
1 W= 1Joule/1Second
1W= 1V * 1A
- Watt Density:
It is defined as the heating element power divided by the heated surface area of the element. It is expressed in W/Cm2 orW/in2, watt density determines the heating element’s operating temperature for a given set of conditions.
- Web Server:
Web server, also known as an internet server, is a device that uses Hypertext Transfer Protocol (HTTP) to serve the files, which are in the form of web pages to users, in response to their requests. The most widely installed web servers are Apache, NGINX, and Microsoft’s Internet Information Server (IIS).
- Wire Size:
Wire size or wire gauge referred as the physical size of the wire rated with numerical designation. Simply, the smaller the wire gauge number, the larger the wire diameter. The wire is sized by the American Wire Gauge (AWG).
- Working Standard:
One of the measurement device that referred to as a secondary standard.
- Watt (W):
XML stands for eXtensible Markup Language. As defined by the Worldwide Web Consortium (WC3), a markup language is a set of rules that are applied for encoding documents in a human or machine readable format. With customized tags, a language enables data sharing between applications, systems, and organizations.