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What are the common safety circuit switches?

Update:11-05-2019
Summary:

Computer room: control panel emergency stop switch, pha […]

Computer room: control panel emergency stop switch, phase sequence relay, thermal relay, speed limiter switch

Well: upper limit switch, lower limit switch (some elevators put these two switches in the safety circuit, and some use these two switches to directly control the power supply)

Pit: Broken rope protection switch, pit repair box emergency stop switch, buffer switch

Inside the car: control box emergency stop switch

Car top: safety window switch, safety clamp switch, car top inspection box emergency stop switch

Fault status: When the elevator is in the stop state, all signals cannot be registered, and the express train cannot run. First, it is suspected that the safety loop is faulty. You should go to the equipment room control panel to observe the status of the safety relay. If the safety relay is in the released state, it should be judged that the safety circuit is faulty.

Possible causes of failure:

The phase sequence of the input power supply is incorrect or there is a phase loss that causes the phase sequence relay to operate.