# Basic terms commonly used in instrumentation and its definition **URL:** \ **Category:** Interview Q & A\ **Tags:** interviewquestions\ **Created:** [October 20, 2017, 3:03pm UTC](https://forumautomation.com/t/basic-terms-commonly-used-in-instrumentation-and-its-definition/2483 "2017-10-20T15:03:47Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![sivaranjith](https://forumautomation.com/letter_avatar_proxy/v4/letter/s/ba9def/32.png) [@sivaranjith](https://forumautomation.com/u/sivaranjith)\ **Post date:** [October 20, 2017, 3:03pm UTC](https://forumautomation.com/t/basic-terms-commonly-used-in-instrumentation-and-its-definition/2483/1 "2017-10-20T15:03:49Z")
**INSTRUMENTATION:** A complete set of instruments combinedly used to control a process like production, refining. **INSTRUMENTS:** Devices that are used for measuring, indicating, controlling, recording can be considered as an instrument **TRANSDUCERS:** A device coverts physical quantity into an electrical quantity. Transducers are also known as **Pick-Ups** **CALIBRATION:** Calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. **CONTROLLER:** A device in control loop which regulates the error signals to the zero or devices which regulate the behaviour of other devices or process variable. **TRANSMISSION:** A method of sending data between various instruments of a plant in a standardized form. **TRANSMITTER:** A device which converts measurement value into a standard signal. **PROCESS VARIABLE:** The process variable is the measured value of ongoing part of a process being monitored or controlled. **SET-POINT:** The desired value required by the operator of an essential variable of a system. **ACCURACY:** Accuracy is the conformity of an indicated value to an accepted standard value or it is the limit of error can be made by an instrument in normal operating conditions. **SPAN:** Algebraic difference between the possible upper range value and lower range value