Inovance MD280 Series - Leakage Current Analysis and Mitigation

EMC MD280/MD280N User Manual
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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:
Aǃ 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 grounded; 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.
Bǃ 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 shall install EMC filter between the inverter and the power supply
(refer to Section 7.3.6 for the prototyping operation);
Cǃ The surrounding equipment is separately grounded, which
can avoid the interference caused by the leakage current of the
inverter’s grounding wire when common grounding 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 of affecting the ground leakage current and solutions:
There are distributed capacitance between the lead cables and the
earth. The larger the distributed capacitance is, the larger the
leakage current will be. The distributed capacitance can be reduced
by effectively reducing the distance between the inverter and the
motor. The higher the carrier frequency is, the larger the leakage
current will be. The leakage current can be reduced by reducing the
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