Installation & Connection
7-15
AC10 Inverter
7.7.5 Leakage Current
Leakage current may flow through the drive’s input and output capacitors and the motor. The
leakage current value is dependent on the distributed capacitance and carrier wave frequency.
The leakage current includes ground leakage current and the leakage current between lines.
Ground Leakage Current
The ground leakage current can not only flow into the drive system, but also other equipment
via earthing cables. It may cause the leakage current circuit breaker and relays to falsely trip.
The higher the drive’s carrier wave frequency, the bigger the leakage current, also, the longer
the motor cable, the greater the leakage current.
Suppressing Methods:
•
Reduce the carrier wave frequency, but the motor noise may be louder;
•
Motor cables should be as short as possible;
•
The drive and other equipment should use leakage current circuit breaker designed for
protecting the product against high-order harmonics/surge leakage current.
Leakage Current Between Lines
The line leakage current flowing through the distribution capacitors of the drive outside may
cause the thermal relay to be falsely activated, especially for the drive whose power is lower
than 7.5kW. When the cable is longer than 50m, the ratio of leakage current to motor rated
current may be increased and can cause the wrong action of external thermal relay very easily.
Suppressing Methods:
•
Reduce the carrier wave frequency, but the motor noise may become louder;
•
Install reactor at the output side of the drive.
In order to protect the motor reliably, it is recommended to use a temperature sensor to detect
the motor’s temperature, and use the drive’s over-load protection device (electronic thermal
relay) instead of an external thermal relay.
7.7.6 Electrical Installation of the Drive
Drive
AC input reactor
Circuit breaker
EMI filter
Power source
cable of drive
AC output reactor
Motor
>20cm
>30cm
>50cm
Metal
cabinet
Metal
cabinet
Isolation
transformer
Power source
cable of meters
Control
cable
Motor cable
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Summary of Contents for 10G-11-0015 Series
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