Eliminating interference and eliminating noise is only an ideal. At present, it cannot be absolutely eliminated. Only some technical means can be used to reduce electromagnetic interference and reduce electromagnetic interference noise. From the previous noise source analysis, since some sources of noise current are inverters, this noise current must flow back to the inverter, otherwise the noise current will seriously interfere with the elevator power supply circuit and control circuit. These interferences are mainly pulse interference and continuous interference. If such interference is not eliminated, the damage is very serious, and the above-mentioned unsafe phenomenon or failure may occur in the elevator operation.
Most of the early frequency conversion elevators did not have a shielded jacket wire on the motor power line. The noise current in the line could not be effectively returned through the shielded line and the PE (the same grounding protection) connection point, and electromagnetic interference noise was induced. What’s more, some of the inverter cable and output power cable are not equipped with shielded wires, and electromagnetic interference is increased, which is also the main reason for the increase of electromagnetic noise in the elevator engine room. Elevator control system and inverter system require strong anti-interference ability and small interference. First, we must understand three basic components of electromagnetic interference: electromagnetic interference source, coupling path and sensitive components. Among the three basic elements, there is no electromagnetic interference caused by the lack of any one element. However, in a normal electromagnetic production environment, no single element can be lacking because of the design of the elevator inverter, electronic circuit, and control circuit. The manufacturing and installation have been finalized, and the anti-interference and internal quality of equipment and products have not changed.
If the electromagnetic interference problem is to be solved, only the electromagnetic interference source and the coupling path can be taken in daily work to reduce or reduce electromagnetic interference. Common technical methods for anti-electromagnetic interference include shielding, grounding, filtering, wiring, isolation, and reasonable wiring. By adopting the above technical measures for electromagnetic interference sources and coupling paths, electromagnetic interference can be effectively reduced or eliminated. Commonly used in shielding technology are electrostatic shielding, alternating electromagnetic field shielding, low frequency magnetic field shielding, and high frequency magnetic field shielding. The most used in elevator design and installation is magnetic field shielding technology.