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A-13
Measures to be taken:
1. Use the electronic thermal function provided for the inverter.
Use parameter
, to set the electronic thermal function.
2. Lower the PWM carrier frequency, though this results in an increase in motor magnetic noise.
Use parameter
to lower the PWM carrier frequency.
3. For improvement, connect film capacitors with capacitance of 0.1 to 0.5 F-1000V to the
input and output terminals in each phase of the each thermal relay.
CT and ammeter
When a CT and an ammeter are installed externally to monitor the output current of the
inverter, the ammeter could be burned by the high-frequency elements of a leakage current.
For a model with relatively long cables (longer than 50 m) or a model for motors with small
current ratings (several amperes), especially 400V model with a small capacity (3.7kW or less),
the ammeter can be burned more easily by the high-frequency elements of a leakage current
which flows into it through the external CT because a leakage current can be too large as
compared with the current rating of the motor.
Measures to be taken:
1. For external meters, use the meter output terminals in the inverter's control circuit.
Output currents can also be output to the meter output terminals (AM). Use a 1 mAdc full-
scale ammeter or a 7.5 Vdc-1 mA full-scale voltmeter.
2. Use the monitor function provided for the inverter.
Use the monitor function provided for the inverter to check the output current.
Power
supply
Inverter
IM
A
IM
U/
T1
V
/
T2
W
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T
3