VFD external electromagnetic inductive interference

If there are interference sources around the variable frequency drive, they will invade into the VFD by radiation or power cable, to cause the control circuit malfunction, and result in machine not work or shut down, even cause the VFD damaged. The specific method to reduce noise interference: Install anti-surge voltage absorption devices to the wirings of relays and contactors around variable frequency drive, such as RC surge absorber, the wiring length should not exceed 20 cm; minimize control loop wiring length, and separate it from the main circuit; the VFD control circuit wiring twist distance should be more than 15 mm, and keep 10cm at least with the main loop circuit; If the variable frequency drive is far from the electric motor (over 100 m), then, on one hand we can increase the conductor cross-sectional area, to ensure the wire voltage decrease within 2%, and install the VFD output reactors to compensate the distributed capacitance charging current for long wires. VFD ground terminals should be grounded well, it must be grounded in a dedicated ground point, and can not be mixed with welded and power ground wires; Install radio noise filter on variable frequency drive input side to reduce high harmonics, thereby to reduce the noise impact from the power lines to the electronic equipment; and install radio noise filter on VFD output side to reduce its output line noise for the same.