Instrumentation & Controls Engineering

instrumentation banner 3Instrumentation and controls engineering (I&C) is a branch of engineering that focuses on the measurement, control, and automation of industrial processes.  I&C engineers use a variety of tools and techniques to design, install, and maintain control systems that monitor and adjust the operation of industrial equipment, such as pumps, valves, and turbines.  The work of an I&C engineer typically involves selecting and integrating sensors, actuators, and controllers to create a system that can monitor and control a process.  They may use various technologies, such as programmable logic controllers (PLCs), distributed control systems (DCS), or supervisory control and data acquisition (SCADA) systems, to manage and optimize industrial processes.

Instrumentation & Controls Engineering Index

I&C engineers work in a variety of industries, including oil and gas, power generation, chemical manufacturing, and water treatment.  They are responsible for ensuring that industrial processes operate safely, efficiently, and reliably, while also minimizing environmental impact and complying with regulatory requirements.

In addition to designing and installing control systems, I&C engineers also perform testing, troubleshooting, and maintenance to ensure that systems continue to operate properly over time.  They may also work on projects related to process optimization, plant modernization, or system upgrades.  I&C is a critical field that plays a key role in many industries.  By designing and maintaining control systems that monitor and adjust industrial processes, I&C engineers help to ensure that our modern infrastructure operates safely and efficiently, while also minimizing environmental impact.


Science Branches

Applied Science
Electrical Engineering

Instrumentation & Controls Engineering standards

API Standards

  • API RP 521 - Guides for Pressure Relief and Depression Systems
  • API RP 550 - Manual on Instrumentation of Refinery Instruments and Control Systems
  • API RP 551 - Process Measurement Instrumentation
  • API RP 552 - Transmission Systems
  • API RP 554 - Process Instruments and Controls
  • API RP 598 - Valve Inspection and Testing

ISA Standards

  • ISA 5 - Documentation of Measurement, and Control Instruments and Systems
  • ISA 5.1 - Instrimentation Symbols and Identification
  • ISA 12 - Electrical Equipment for Hazardous Locations
  • ISA 18 - Instrument Signals and Alarms
  • ISA 37 - Instrument Transducers
  • ISA 50 - Signal Compatibility of Electrical Instruments
  • ISA 60 - Control Centers
  • ISA 75 - Control Valve Standards
  • ISA 82 - Electrical and Electronic Instrumentation
  • ISA 90 - Instrumentation and Computer Grounding
  • ISA 91 - Criticality Ranking for Instrumentation
  • ISA 99 - Industrial Automation and Control Systems Security
  • ISA 100 - Wireless Systems for Automation
  • ISA 101 - Human-Machine Interface
  • ISA 104 - Device Integration
  • ISA 106 - Process Automation for Continuous Process Operations
  • ISA 107 - Advanced Measurement Techniques for Gas Turbine Engines
  • ISA 108 - Intelligent Device Management


Instrumentation & Controls Engineering Glossary



  • Background Noise  -  Interfering signals that can cause disturbance affecting a signal that may distort the intended signal.
  • Backplane  -  A group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus.  It is used as a backbone to connect several printed circuit boards together to make up a complete computer system.
  • Batch process  -  Any process on which operations are carried out on a limited number of articles, as opposed to continuous process.
  • Bus  -  The group of conductors that interconnect individual circuitry in a computer. Typically, a bus is the expansion vehicle to which I/O or other devices are connected. Examples of PC buses are the ISA and PCI buses


  • Cache  -  High-speed processor memory that buffers commonly used instructions or data to increase processing throughput.
  • Capacitance  -  The ability to hold an electric charge.
  • Car Seal  -  Specified on instrument bubbles on Piping and Instrumentation Diagram.
  • Carrier Frequency  -  The transmission of a fixed frequency that has been changed or modified to carry data or information.  The frequency is usually measured in Hertz (cycles per second).
  • Channel List  -  A variable length list of channels and their associated gains specifying which analog input channels to convert to digital values.  In continuous A/D acquisition mode, the list wraps around to the first channel after it reaches the end.  The channels need not be in any particular order.
  • Current  -  The rate of flow of electricity in a circuit, measured in amperes.  Amp is a unit of current.  One ampere (amp) is the current flowing through one ohm of resistance at one volt potential.
  • Current Drive Capability  -  The amount of current a digital or analog output channel is capable of sourcing or sinking while still operating within voltage range specifications.


  • Data Length  -  Indicates the set data format.
  • Data Recorder  -  Another name for a data logger, though data recorders are typically higher performance and offer higher sample rates than a typical data logger.
  • Differential Pressure Flowmeter  -  There are many different types of instruments for measuring pressure.  The functions of these instruments are to monitor and control pressure in a process stream.
  • Differential Set Pressure  -  The pressure difference between the set pressure and constant back pressure.
  • Discrete Input  -  Relative to the device that reads either a TRUE or a FALSE, 1 or 0, or ON of OFF as an input signal.


  • Ethernet  -  A family of computer networking technologies for local area networks (LANs) first introduced in 1980.  Systems that use Ethernet for communications divide a stream of data into individual packets called frames.  Each frame contains source and destination addresses and error-checking data so that damaged data can be detected and re-transmitted.
  • Electric Current  -  The rate of flow of electricity in a circuit, measured in amperes.
  • External Trigger  -  A voltage pulse from an external source that trig- gers an event such as A/D conversion.


  • Filter  -  A device that allows certain parts of a signal to pass through while blocking others.  In data acquisition systems, the most common type of filter used is a low pass, anti-aliasing filter.
  • Firewall  -  A device or set of devices designed to permit or deny network transmissions based upon a set of rules and is frequently used to protect networks from unauthorized access while permitting legitimate communications to pass.
  • Flow Quality Indicating Transmitter  -  , abbreviated as FQIT, is an instrument that is used for measuring the amount of a liquid and a gas in two pase flow.
  • Flow Switch  -  Provides a discrete input to the PLC.  The flow switch is typically used as a method of control in tanks, vessels, pumps and other types of process equipment.
  • Flowmeter  -  An instrument used to measure the flow rate of gasses and liquids.


  • Gain Accuracy  -  A measure of deviation of the gain of an amplifier from the ideal gain.
  • Gauge Factor  -  A measure of the ratio of the relative change of resistance to the relative change in length of a piezoresistive strain gage.
  • Grounded Junction  -  A form of construction of a thermocouple probe where the hot or measuring junction is in electrical contact with the sheath material so that the sheath and thermocouple will have the same electrical potential.


  • Half Bridge  -  Two active elements or strain gages.


  • Input Impedance  -  The resistance measured across the excitation terminals of a transducer.
  • Insulation Resistance  -  The resistance measured between two insulated points on a transducer when a specific DC voltage is applied at room temperature.
  • Integral Control  -  A control action that eliminates the steady-state offset inherent in proportional control.
  • Interface  -  The means by which two systems or devices are connected and interact with each other.
  • Interrupt  -  A computer signal indicating that the CPU should suspend its current task to service a designated activ- ity.


  • Junction  -  The point in a thermocouple where the two dissimilar metals are joined.



  • Loop Resistance  -  The total resistance of a thermocouple circuit caused by the resistance of the thermocouple wire.  Usually used in reference to analog pyrometers which have typical loop resistance requirements of 10 ohms.


  • Manual Reset  -  The adjustment on a proportioning controller which shifts the proportioning band in relationship to the set point to eliminate droop or offset errors.
  • Maximun Operating Temperature  -  The maximum temperature at which an instrument or sensor can be safely operated.
  • Maximum Power Rating  -  The maximum power in watts that a device can safely handle.
  • Meter  -  A device that provides a measurement for the flow change in a gas or liquid.
  • Motherboard  -  The pc board of a computer that contains the bus lines and edge connectors to accommodate other boards in the system.  In a microcomputer, the motherboard contains the microprocessor and connectors for expansion boards.
  • Mounting Error  -  The error resultant from installing the transducer, both electrical and mechanical.
  • Multiplex  -  A technique which allows different input or output signals to use the same lines at different times, controlled by an external signal.


  • Noise  -  An undesirable electrical signal.  Noise comes from external sources such as the AC power line, motors, generators, transformers, fluorescent lights, solder- ing irons, CRT displays, computers, electrical storms, welders, radio transmitters, and internal sources such as semiconductors, resistors, and capacitors.





  • Repeatability  -  The ability of the switch to actuate repeatedly at the desired set point within sensor tolerance.Reset Point  -  After the pressure has reached set point and operated the electrical switch, it must return to the reset point before the electrical switch returns to its original position.
  • Resistance Temperature Detectors  -  A sensor used to measure temperature by correlating the resistance of the element with temperature.


  • Shunt  -  A calibrated low resistance connected in parallel with the input terminals of an ammeter in order to enable measurement of higher currents. It can be internal or external.


  • Temperature Controller  -  An instrument designed to minimize operator input or involvement.  A temperature controller has an input that is connected to a temperature source such as an RTD or other type of temperature element.
  • Temperature Differential Switch  -  Contains the same functionality of a temperature switch with the exception that it is looking for the difference of temperature rather than a single input.
  • Temperature Recorder  -  A device that records the temperature of a process.  This could be a data logger or a temperature transmitter capable of storing data.
  • Temperature Switch  -  Provides alarm, shutdown and control for many types of processes.  Switch that activates when a certain temperature condition is met.
  • Termination  -  A load connected to the end of a transmission line.  To avoid signal reflections, it must match the characteristic impedance of the line.
  • Thermopile  -  A number of thermocouples connected in series, arranged so that alternate junctions are the referenced temperature and at the measured temperature to increase the output for a given temperature difference between the measuring and reference junctions.
  • Thermowell  -  Used in temperature measurement and provide isolation from the temperature sensor and the process fluid.



  • Variable Data  -  Numerical information that can be changed during application operation.  It includes timer and counter accumulated values, thumbwheel settings, and arithmetic results.
  • Velocity Flowmeter  -
  • Volt  -  A unit of electrical pressure.  One volt is the amount of pressure that will cause one ampere of current in one ohm of resistance.
  • Voltage  -  The value of electrical potential difference across a conductor expressed in volts.


  • Watt Density  -  The watts emanating from each square inch of heated surface area of a heater.




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