Ø  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.

Ø  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. Instruments often comprise control systems of varied processes such as in power plant.

Ø  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.

Ø  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.

Ø  It is obvious that we need to monitor that power plants parameters and setting points to have faster reaction within milliseconds. Systems used to monitor the power plants, link the field instruments to the control room or main display through Monitoring Systems like PMS (Power Monitoring System), SAS (substation automation system) or OSAS (Open Substation Automation System).

Ø  Power plant instrumentation is used to analyse, detect, measure and record the process parameter and if any deviation found it should be control by the final control element i.e. any valve or regulating unit.

Instruments which easily control the process from remote area and give the desired output through feedback system without any manual operation is known as control instrumentation or automated instrumentation, here in our power plant we have the application of this type of instrumentation