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Main circuit terminals
1.2.5
Leakage current and installation of earth leakage circuit
breaker
Due to static capacitances existing in the inverter I/O wiring and motor, leakage
currents flow through them. Since their values depend on the static capacitances,
carrier frequency, etc., take the following countermeasures.
(1) To-earth leakage currents
Leakage currents may flow not only into the inverter's own line but also into the
other line through the earth cable, etc.
These leakage currents may operate earth leakage circuit breakers and earth
leakage relays unnecessarily.
Countermeasures
If the carrier frequency setting is high, decrease the carrier frequency (Pr. 72) of the
inverter.
Note that motor noise increases. Selection of Soft-PWM control (Pr. 70) will make it
unoffending. (Factory setting)
By using earth leakage circuit breakers designed for harmonic and surge
suppression in the inverter's own line and other line, operation can be performed
with the carrier frequency kept high (with low noise).
10
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