What are the functions of an Instrument?

interviewquestions
instrumentation

#1

The primary function of an instrument is to measure a process variable. While doing so, it performs several functions such as Transmitting,Signaling,Registering,Indicating,Recording.

Transmitting – Instrument sends the information concerning the measured quantity over some distance.
Transmitters are used in process control loop.

Signaling – Instruments indicates the general value or range of values of its measured quantity.

Registering – Instrument indicates by numbers or some other symbol of discrete increments, the value of the quantity being measured.

Indicating – An indicating instrument indicates the instantaneous value of the variable being measured at that time. Such an instrument normally uses a calibrated scale and pointer.

Recording – Instruments makes a written record of the value of the measured quantity against some other variable or against time.


#2

An instrumentation system is an assembly of various devices or components to form an integral whole, for observation, monitoring or control purposes.In other words,it is defined as the design, construction, and provision of instruments for measurement, control etc.
eg-home security system,weather radar,thermostat,CT-scan,MRI- machine etc

Instrumentation system can be classified into following categories:

On the basis of signal:

  1. Analog instrumentation system.
  2. Digital instrumentation system.

On the basis of response:

  1. Intelligent instrumentation system.
  2. Dumb instrumentation system.