What is the elevator limit switch ?
Elevator limit switch is a device used to cut off the main control power supply when the elevator runs beyond its normal range of travelling. Usually, there are four kinds of limit switches on elevator: Car Top Limit Switch; Bottom Limit Switch; Overspeed Governor Limit Switch & Shaft Lighting Limit Switch.
Their functions are to ensure the safety of the repairer，passengers, and elevator equipment, as well as to prevent the car from continuing to travel even after it reaches the top or bottom floor (topping or bottoming out) due to the failure of the elevator’s electrical system.
How to connect the elevator limit switch wires?
1. Car Top Limit Switch Wiring
The top limit switch is usually installed at the top of the elevator shaft to detect whether the top of the elevator is in place or not. Its wiring method is to connect the switch normally closed end to the STOP wire in the control cable, and the normally open end of the switch to the NFRM wire in the control cable. Do not bypass the limit switch to avoid a safety hazard.
2. Bottom Limit Switch Wiring
Bottom limit switch is generally installed at the bottom of the elevator shaft to detect whether the bottom of the elevator is in place. Its wiring method is similar to the top limit switch, connecting its normally close end to the NFRM wire in the control cable, and connecting the normally open end to the AB wire in the control cable.
3. Overspeed Governor Limit Switch wiring
The speed limiter switch is usually installed in the elevator machine room to detect whether the speed of the elevator is normal or not. The speed limiter switch is wired by connecting the normally close end to the speed sensor in the control cable and the normally open end to the motor brake in the control cable.
4. Shaft Lighting Limit Switch Wiring
The shaft lighting switch is generally installed in the elevator shaft to control whether the shaft lighting is turned on or not. Its method of wiring is to connect the normally open end to the lamp in the control cable, and to connect the normally closed end to the NFRM wire in the control cable.
When wiring, be sure to operate in strict accordance with the standards in the manual to ensure the safe operation of the elevator. In addition, Regularly checking the limit switch working status and timely replacing the damaged switches are also important measures to ensure the safety of the elevator.
