Experts repair elevators. They have always been able to rely on the phenomenon of failure. Analyze the cause and quickly determine the real cause of the fault or determine the specific location of the fault. Therefore, repairing the elevator requires not only continuous summarization and accumulation of troubleshooting experience, but also some skills to confirm the fault. This article describes in detail three techniques for acknowledging faults.

1 Confirmation of Rotary Encoder Malfunction

The fault caused by the rotary encoder is not a minority in practice, but it is also very troublesome to check. Sometimes it has been checked, but it is still not reassuring. Therefore, here are ten simple ways to confirm the fault of the rotary encoder. From the simple drive adjustment system It can be clearly seen from the figure that it is because of the rotation coding that the microcomputer, the inverter and the motor are connected. It constitutes a speed closed-loop control system. Therefore, if there is a problem with the rotary encoder, the abnormal feedback signal will inevitably affect the normal operation of the motor. If we simply disconnect the feedback of the rotary encoder at this time - it becomes an open-loop control , If the motor can still be in a normal and fast running state, then it can be determined that the fault of the elevator really occurs on the rotary encoder, otherwise, the fault should be found in other aspects. This is the theory and method of confirming the fault of the rotary encoder.

Of course, for safety reasons, when the feedback running is disconnected, the elevator should not run to the upper and lower end stations.

2 Quick confirmation of door lock fault location

Door interlock faults account for a relatively high proportion of elevator faults. For door interlock faults, it is easy to confirm them in the control cabinet of the machine room by checking the display or checking the fault code. It is not difficult to find and eliminate one by one, but if you encounter a high-rise building, such as a high-rise building with 40 or 50 floors, how to quickly and accurately find the floor where the door interlock failure is located? When the elevator cannot run due to the door interlock failure , First, find the terminal of the car door switch and the terminal of the hall door switch on the wiring row of the control cabinet in the machine room. When the car door and the hall door are all closed, measure whether the car door switch and the hall door switch are turned on respectively. If The measurement result is that the car door switch is on, and the hall door switch is off, and the following subsection method can be used to continue the judgment.

First, short-circuit lines 01 and 11 on the door lock circuit so that the elevator can operate up and down. The maintenance personnel entered the car top and found lines 01 and 10 on the car top junction box. Assuming that the elevator has 40 floors and 40 stations, press the slow travel button on the car top to the middle floor station such as the 20th floor station, open the car door and hall door of the 10th floor station, and close all the other hall doors. Connect one end of a wire to No. 01 line of the car top wiring, and the other end to a multimeter and a test lead. If one of the two contacts of the interlock switch is connected with a multimeter, it means that the interlock switches of the 21st-40th floor station door are all turned on; if the multimeter cannot be turned on, it means that the 21st-40th floor station door interlock switch There is an open circuit. The same method can judge the door interlock switch of 1-1 9th floor. As for the 20th floor, the on-off of the two contacts of the door interlock switch can be measured after the door is closed. Then, take 1/2 of the floor station as the measurement point in the half of the floor station that has been judged to be open, so that the floor station with the exit interlock and open circuit can be quickly found.

3 Confirmation of the fault of the door knife rubbing the door roller

There is a sudden stop of the elevator during operation, which may be caused by the instantaneous on-off of the door lock circuit (manually splitting), or it may be caused by the speed limiter tensioning device touching the broken rope switch in an instant, of course, it may also be It is caused by the door knife rubbing the door roller when the elevator is running. If you open a professional elevator maintenance book, you will see that there are at least Japanese reasons that can cause the sudden stop of the elevator. So, how to confirm the fault of the door knife rubbing the door roller?

For elevators controlled by PLC, the program shown in Figure 2 can be inserted between OUT (M21) and OUT (M111) of the program, where M21 is the running relay and X14 is the door lock relay contact. After the fault occurs, check the K value of the counter C224 in the PLC, and compare it with the K value checked last time. If it is found that it has increased by 1 time, it can be confirmed that the elevator has the problem of the door knife wiping the door roller.

Maintenance personnel often encounter various phenomena in their work. If they carefully investigate and analyze, and are good at summarizing and improving, they will definitely provide many shortcuts for future work.