ACD320user manual
Installation and wiring
C) Ground the external equipment and eliminate the disturbance of the leakage current fromthe
inverter's grounding cable.
3.6.3 Leakage current
The inverter has two kinds of leakage current, one is the grounding leakage current and another
is the leakage current between the lines:
1) Grounding leakage current:
The distributed capaci tance exists between the cables and the ground, and the bigger the
capacitance and the bigger the leakage current, so themotor cables should be as short as possible.
Besides, the bigger the carrier frequency is, the bigger the leakage current is, so the user can also
reduce the carrier wave frequency, but themotor noise may increase. Installing reactor can also
reduce the leakage current.
The leakage current is increasedwith the increase of the circuit current, so the leakage current is
big if the motor power is big.
2) Leakage current between lines:
The distributed capacitance exists in the inverter output cables, andresonancemayoccurifhigh
frequency harmonics exist in the current, thus the leakage current occurs, which may result in the
wrong action of relay.
The method to solve this issue is to reduce the carrier frequency or install the output reactor. It is
recommended to use inverter protection function instead of a thermal relay to protect themotor
before using the inverter.
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