The so-called safety circuit refers to the installation of a safety switch in each safety component of the elevator, which connects all safety switches in series to control a safety relay. Only when all safety switches are turned on and the safety relay is activated can the elevator be powered on for operation.

1. The phase sequence error or missing phase of the input power supply causes the phase sequence relay to operate.
2. The elevator is operating under overload or locked for a long time, causing the thermal relay to act.
3. It is possible that the overspeed of the speed limiter may cause the speed limiter switch to act.
4. The limit switch action is caused by the elevator hitting the top or sinking to the bottom.
5. The pit rope break switch operates. It may be due to the governor rope jumping out or being too long.
6. Safety gear action. The cause should be identified. It may be due to the overspeed action of the speed governor, incorrect operation of the speed governor due to loss of oil, loss of oil on the pit rope pulley, foreign objects (such as mice) getting entangled in the pit rope pulley, and too small clearance between safety blocks.
7. The safety window is lifted by someone, causing the safety window switch to operate.
8. Some emergency stop switches may have been pressed by someone.
9. If all switches are normal, check if their contact points are in good condition and if the wiring is loose.