In order to ensure the elevator running safely, there are many safety parts on the elevator. The elevator run based on each safety component in normal condition, otherwise it will be stopped. The so-called safety circuit is to install a safety switch in each safety elevator part, all safety switches are connected in series, controlling a safety relay. Only when all the safety switches are on, the safety relay is closed, and the elevator can run electrically.
Safety component switch of common elevator safety circuit:
- Speed limit switch (including speed limiter cut rope switch) – when the elevator at a faster rate than the rated speed value must be at least equal to the rated speed (115%), its action can lead to safety clamp work safety device.
- Maintenance switch — divided into control cabinet maintenance switch, car maintenance switch and car top maintenance switch. The three repair switches lock each other to prevent wrong operation and ensure the safety of maintenance personnel.
- Bottom pit buffer switch — this device is located at the bottom of the well path and is set at the bottom limit position of the car and the counterweight stroke. In the buffer (an elastic buffer safety device used to absorb the car and against heavy kinetic energy). After the action, the elevator cannot operate normally until it returns to its normal elongation position.
- Upper and lower limit of interlock switch, when the car running beyond magnetic induction device, flat layer in capsules or have not contact with buffer before the weighing device, forced to cut off the main power supply and control power of the safety device of automatic reset. The device is located as close as possible to the end of the station when working without error in the dangerous position of movement. It shall operate in the cage or before heavy (if any) contact with the buffer and maintain its action status during compression of the buffer. For the forced drive elevator, the limit switch is used to cut off the power supply circuit of the motor and brake. The elevator cannot resume operation automatically after the limit switch action.
- Safety clamp switch — check whether the speed limiter is operating. When the speed limiter moves, then a mechanical safety device that keeps the car or the car in a static state and can clamp the guide rail.
- Safety window switch — means that the car safety window is equipped with a safety device for manual locking. If the lock fails, the device can stop the elevator. The elevator will not be able to resume operation until it is re-locked.
- Door and door interlock switch — door and door of the hall are locked after closing, and the control loop is connected at the same time. The safety device of mechanical & electrical interlock safety device can only operate the car. Its function is that when the elevator car stops at a certain floor station, the door of the other floor station is effectively locked, and if the elevator is opened, it cannot start or keep running normally.