Control circuits that shut down elevator power must be monitored for what condition?

Control circuits that shut down elevator power must be monitored for what condition?

• A. Presence of operating voltage
• B. Absence of voltage
• C. Ground fault
• D. Temperature

Answer: (A)

Safety-related control circuits that shut down elevator power must be monitored to ensure they have the voltage they need to perform their protective function. If the supply to the shutdown circuit drops or is absent, the circuit may not be able to trip and remove power when required, leaving the elevator energized and creating a hazard. By monitoring for the presence of operating voltage, you verify the control circuit is energized and within the proper range so a commanded shutdown will reliably occur. Checking for absence of voltage wouldn’t guarantee the ability to trip, because it would only tell you the circuit is already unpowered. Ground fault and temperature checks address other failure modes and are not the primary way to ensure the shutdown path can act when needed.

Safety-related control circuits that shut down elevator power must be monitored to ensure they have the voltage they need to perform their protective function. If the supply to the shutdown circuit drops or is absent, the circuit may not be able to trip and remove power when required, leaving the elevator energized and creating a hazard. By monitoring for the presence of operating voltage, you verify the control circuit is energized and within the proper range so a commanded shutdown will reliably occur. Checking for absence of voltage wouldn’t guarantee the ability to trip, because it would only tell you the circuit is already unpowered. Ground fault and temperature checks address other failure modes and are not the primary way to ensure the shutdown path can act when needed.