Application of frequency converter and PLC in elevator and treatment of abnormal problems

The abnormal problem you mentioned should be the safety protection of the elevator. This is mainly done by PLC, and all possibilities have to be considered. In the scheme, the frequency converter is only used to lift the elevator car, because at present, the frequency converter is probably the only motor with better speed change effect. If the elevator is stuck in an abnormal situation, the general frequency converter will give an alarm, and the PLC will receive the signal, output a contact, and trigger the alarm system to inform the general control room. In fact, I think a small detection program should be added to the elevator programming: when the elevator is running, a timer will work at the same time, and every time it passes through a floor, the switch signal will be detected and the timer will be reset. If the elevator is running and the timer does not detect the floor signal within a certain period of time, it can be judged that the elevator is stuck in the middle! This program has nothing to do with floor calculation, but it can be triggered by elevator operation command.

For reference only, because there is no elevator program, I really don't know what an abnormal problem is, mainly the scene where the elevator is stuck in the middle of the floor in the movie.

To say a few more words, the elevator in Beijing subway station suddenly reversed, although the final reason is unknown. I just suspect from the mechanical analysis that the forward and reverse rotation of the elevator is switched by the gearbox, and it is impossible for the motor controlled by the normal frequency converter to suddenly reverse when it rotates forward. It is possible that the reversing electromagnet of the gearbox suddenly gets power (disconnection, short circuit, etc.). ), or the gears in the gearbox are badly worn and arranged in disorder, causing the elevator to suddenly reverse. It's just a personal guess.

Today, I occasionally turn to this answer and want to say more.

The residential area where I live is Evergrande hardcover room, and the elevator belongs to Otis. When I first delivered the house, the elevator fell straight from the seventh floor to the end, and I was in the elevator. What a shock! ! When I found the property, I also called Otis after-sales staff. After a long search, there was no result, because the elevator was normal again. After communicating with the after-sales staff, I learned that the elevator in Beijing subway broke down because of the chain, which is easy to understand.