AutoQuiz is edited by Joel Don, ISA’s community manager. 


Today’s automation industry quiz question comes from the ISA Certified Control Systems Technician (CCST) program. Certified Control System Technicians calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables. Click this link for more information about the CCST program. This question comes from the Level I study guide, Domain 3, Troubleshooting. Level I represents a professional who has a five-year total of education, training, and/or experience.


A process variable, which is to be maintained at some desired value (temperature, pressure, level, flow) by means of manipulating another process variable, is the:

a) manipulated variable
b) measured variable
c) controlled variable
d) disturbance variable
e) none of the above


Click Here to Reveal the Answer

The controlled variable by definition is the variable that the control system attempts to keep at a “set point” value. The set point may be constant or it may change. Typically, this part of the process is flow, level, temperature, pressure, or the like.The correct answer is C, controlled variable.


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