E6581697
A-20
1
1.4.3 What to do about the leakage current
Caution
Mandatory
action
The leakage current through the input/output power cables of inverter and capacitance of motor may
affect to peripheral devices.
The value of leakage current is increased under the condition of the PWM carrier frequency and the
length of the input/output power cables. In case the total cable length (total of length between an
inverter and motors) is more than 100m, overcurrent trip may occur even the motor no-load current.
Make enough space among each phase cable or install the filter (MSF) as countermeasure.
(1) Influence of leakage current across ground
Leakage current may flow not just through the inverter system but also through ground wires to other
systems. Leakage current will cause earth leakage breakers, leakage current relays, ground relays, fire
alarms and sensors to operate improperly, and it will cause superimposed noise on the TV screen or
display of incorrect current detection with the CT.
Power
supply
ELCB
Inverter
Inverter
IM
IM
ELCB
Leakage current path across ground
Remedies:
1. If there is no radio-frequency interference or similar problem, detach the built-in noise filter
capacitor, using the grounding capacitor disconnecting switch.
2. Reduce PWM carrier frequency.
The setting of PWM carrier frequency is done with the parameter
.
Although the electromagnetic noise level is reduced, the motor acoustic noise is increased.
3. Use high frequency remedial products for earth leakage breakers
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