KE300A Inverter EMC (Electromagnetic Compatibility)
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3) It is recommended that the output power cables of the inverter employ shield cables or steel pipe
shielded cables and that the shielding layer be earthed reliably. The lead cables of the equipment suffering
interferences are recommended to employ twisted-pair shielded control cables, and the shielding layer
should be earthed reliably.
4) When the length of motor cable is longer than 100 meters, it needs to install output filter or reactor.
7.3.3 Handling method for the interferences of the surrounding equipment on the inverter
The electromagnetic interference on the inverter is generated because plenty of relays, contactors and
electromagnetic brakes are installed near the inverter. When the inverter has error action due to the
interferences, the following measures can be taken:
1) Install surge suppressor on the devices generating interference;
2) Install filter at the input end of the inverter. Refer to Section 7.3.6 for the specific operations;
3) The lead cables of the control signal cable of the inverter and the detection line employ shielded
cable and the shielding layer should be earthed reliably.
7.3.4 Handling method for the interferences of inverter on the surrounding equipment
These interferences include two types: one is radiation interference of the inverter, and the other is
conduction interference of the inverter. These two types of interferences cause the surrounding electric
equipment to suffer electromagnetic or electrostatic induction. The surrounding equipment hereby
produces error action. For different interferences, it can be handled by referring to the following methods:
1) For the measuring meters, receivers and sensors, their signals are generally weak. If they are placed
nearby the inverter or together with the inverter in the same control cabinet, they are easy to suffer
interference and thus generate error actions. It is recommended to handle with the following methods: Put
in places far away from the interference source; do not arrange the signal cables with the power cables in
parallel and never bind them together; both the signal cables and power cables employ shielded cables
and are well earthed; install ferrite magnetic ring (with suppressing frequency of 30 to 1,000MHz) at the
output side of the inverter and wind it 2 to 3 cycles; install EMC output filter in more severe conditions.
2) When the equipment suffering interferences and the inverter use the same power supply, it may
cause conduction interference. If the above methods cannot remove the interference, it should install EMC
filter between the inverter and the power supply (refer to Section 7.3.6 for the prototyping operation); the
surrounding equipment is separately earthed, which can avoid the interference caused by the leakage
current of the inverter’s earth wire when common earth mode is adopted.
3) The surrounding equipment is separately earthed, which can avoid the interference caused by the
leakage current of the inverter’s earth wire when common earth mode is adopted.
7.3.5 Leakage current and handling
There are two forms of leakage current when using the inverter. One is leakage current to the earth, and
the other is leakage current between the cables.
1) Factors influencing the leakage current to the earth and the solutions:
There are distributed capacitance between the lead cables and the earth. The larger the distributed
