Instrumentation and Control

Instrumentation is the branch of engineering that deals with measurement and control.

According to ISA or known as Instrumentation and Systems Automation Society formerly known as Instrument Society of America, the official definition of Instrumentation - is a collection of Instruments and their application for the purpose of Observation, Measurement and Control. Reference: ISA std. S 51.1 – (Instrument Society of America)

An instrument is a device that measures or manipulates variables such as flow, temperature, level, or pressure. Instruments include many varied contrivances which can be as simple as valves and transmitters, and as complex as analyzers. Instruments often comprise control systems of varied processes. The control of processes is one of the main branches of applied instrumentation.

Control instrumentation includes devices such as solenoids, valves, circuit breakers, and relays. These devices are able to change a field parameter, and provide remote or automated control capabilities.

Transmitters are devices which produce an analog signal, usually in the form of a 4–20 mA electrical current signal, although many other options using voltage, frequency, or pressure are possible. This signal can be used to control other instruments directly, or it can be sent to a PLC, DCS, SCADA system, or other type of computerized controller, where it can be interpreted into readable values and used to control other devices and processes in the system.

Instrumentation plays a significant role in both gathering information from the field and changing the field parameters, and as such are a key part of control loops.

Measurement

Instrumentation can be used to measure certain field parameters (physical values):

These measured values include:

• pressure, either differential or static
• flow
• temperature - Temperature_measurement
• level - Level Measurement
• density
• viscosity
• radiation
• frequency
• current
• voltage
• inductance
• capacitance
• resistivity
• chemical composition
• chemical properties
• various physical properties
• process instrumentation
  

Control

In addition to measuring field parameters, instrumentation is also responsible for providing the ability to modify some field parameters.

Instrumentation engineering

Instrumentation engineering is the engineering specialization focused on the principle and operation of measuring instruments which are used in design and configuration of automated systems in electrical, pneumatic domains etc. They typically work for industries with automated processes, such as chemical or manufacturing plants, with the goal of improving system productivity, reliability, safety, optimization and stability. To control the parameters in a process or in a particular system, devices such as microprocessors, microcontrollers or PLCs are used, but their ultimate aim is to control the parameters of a system.

Instrumentation technologists and mechanics

Instrumentation technologists, technicians and mechanics specialize in troubleshooting and repairing and maintenance of instruments and instrumentation systems. This trade is so intertwined with electricians, pipefitters, power engineers, and engineering companies, that one can find him/herself in extremely diverse working situations. An over-arching term, "Instrument Fitter" is often used to describe people in this field, regardless of any specialization.