Operation
Chapter 5
5-2-6 Motor Burns
• The dielectric strength of the motor is insufficient.
Surge arises when the motor (inductive load) is connected to the output side of the
Inverter. Normally, the maximum surge voltage is approximately three times the power
voltage. Therefore, the dielectric strength of the motor to be used must be higher than
the maximum surge voltage.
It is recommended that motors specifically for Inverters be used, especially for the
400-VAC-class Inverters.
5-2-7 Controller Receives Noise when Inverter is
Started
• Noise derives from Inverter switching.
Take the following actions to prevent noise:
SReduce the carrier frequency of the Inverter.
The number of internal switching times is reduced, so noise can be reduced to
some extent.
SImprove the frame ground.
A current generated by internal switching normally leaks into the frame ground.
Therefore, connect the ground terminal with a sufficiently thick and short wire of 100
Ω or less.
SInstall an input noise filter.
Install an input noise filter (3G3IV-PHF) on the power input side of the Inverter.
SInstall an output noise filter.
Install an output noise filter (3G3IV-PLF) on the output side of the Inverter.
SProvide a separate power supply for the sensor.
If the sensor malfunctions, provide a dedicated power supply for the sensor and
install a noise filter on the power supply. For the signal line, use a shielded cable.
5-2-8 AM Radio Receives Noise when Inverter is
Started
• Noise derives from Inverter switching.
Take the following actions to prevent noise:
SReduce the carrier frequency of the Inverter.
The number of internal switching times is reduced, so noise can be reduced to
some extent.
5-11
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