- May 31, 2020
Certified Control System Technicians (CCSTs) calibrate, document, troubleshoot, and repair/replace instrumentation for systems that measure and control level, temperature, pressure, flow, and other process variables.
A control system technician has been requested to design and install a circuit for an exhaust fan in a nonhazardous process location that is protected against electrical overload and for which the operator will be able to reset the circuit if it trips.
B. fusible link
C. thermal-magnetic circuit breaker
D. conditioning power supply
The correct answer is C, thermal-magnetic circuit breaker. Both a fuse and a fusible link can be used to break the circuit in an over-current situation, but fuses and fusible links are not resettable. They must be replaced once tripped.
A conditioning power supply, while able to remove fluctuations in voltage and power output to the circuit, is not able by itself to disconnect a circuit in case of short circuits or electrical surges.
Reference: Goettsche, L.D. (Editor), Maintenance of Instruments and Systems, Second Edition, ISA, 2005.
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