Elevator fault treatment caused by electromagnetic interference - Database & Sql Blog Articles

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With the rapid development of computer technology, especially the microcomputer with greatly reduced cost is widely applied to the control part of the elevator, even using multi-computer control and serial communication transmission call signal, etc., the drive part adopts variable frequency variable voltage (VVVF) speed regulation. The system has become a popular standard design for elevators. In recent years, the frequency conversion door machine has also become fashionable, replacing the original DC door machine with resistance speed regulation. The wide application of the microcomputer has higher and higher requirements for the reliability of the elevator control system, which is mainly the anti-interference reliability. The main external factors encountered in elevator operation are: temperature, humidity, dust, vibration, shock, power supply voltage, current, frequency fluctuation, high frequency interference generated by the inverter itself, operator error and load Changes and so on. Under the influence of these disturbances, the elevator will produce errors and faults. The electromagnetic interference of the elevator mainly has the following three forms:
(1) Power supply noise: It mainly invades the system from the power supply and power supply incoming lines (including ground). In particular, power supply noise is generated when the system shares power with other frequently changing large loads. When the power supply lead is long, the voltage drop occurs during the transmission process, and the induced potential also generates noise interference, which affects the normal operation of the system. The power supply noise may cause the microcomputer to lose part or most of the information, causing errors or malfunctions.
(2) Noise intruding from the input line. When the input line has a common ground line with its own system or other systems, it will invade this noise. Sometimes, even if isolation is used, it will still be affected by the electromagnetic induction coupled with the input line. If the input signal is very small, It is very easy to make errors and malfunctions in the system.
(3) Static noise: It is caused by friction. The static electricity generated by friction is very small, but the voltage can be up to tens of thousands of volts. The materials provided by the IEEE Reliability Physics Symposium show that people who walk on the blankets can carry up to 39KV, and those who work at the workbench can also reach 3KV, so when people with high potential touch the computer board, the human body The charge is discharged to the system, and the sharp discharge current causes noise, which affects the system operation and may even cause damage to electronic components.
Anti-interference measures must be adopted for the above conditions, and the anti-interference measures themselves should be correct and reliable, otherwise the elevator will be faulty.
(4) Faults caused by improper electrical or electronic components damage or position adjustment: The electrical system of the elevator, especially the control circuit, has a complicated structure. In the event of an accident, it is necessary to quickly eliminate the fault. The experience alone is not enough, which requires the maintenance personnel to Master the working principle of the electric control circuit and the working process of the control link, clarify the relationship between each electrical and electronic components and their functions, and understand the installation position of each electrical component. Only in this way can the fault occurrence point be accurately judged, and Quickly rule out. On the basis of summarizing and applying other people's actual work experience, it is beneficial to quickly eliminate faults and reduce losses, because some faults in operation are still regular.