ISA Certified Automation Professional (CAP) program

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Certified Automation Professionals (CAPs) are responsible for the direction, design, and deployment of systems and equipment for manufacturing and control systems.

CAP question

A Markov model is used to determine successful system operation as a function of operating time interval. The resulting computation indicates system

A. mission time
B. steady-state availability
C. reliability
D. probability of success

CAP Answer

The correct answer is B, “steady-state availability.”

Systems that exhibit a Markov property are ones in which the future does not depend on the past. Therefore, instantaneous availability will vary during the operating time interval, due to changes in failure probabilities and repair situations.

Availability is often calculated as an average over a long operating time interval. The result indicates that availability reaches a “steady state” after some period of time.

Reference: Trevathan, Vernon L., A Guide to the Automation Body of Knowledge, Second Edition, ISA, 2006


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