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Troubleshooting
8-2-7
Controller or AM Radio Receives Noise when Inverter is Started
Noise derives from
Inverter switching.
8-2-8
Ground Fault Interrupter is Actuated when Inverter is Started
Leakage current flows
through the Inverter.
8-2-9
Mechanical Vibration
Mechanical system makes unusual noise.
Resonance between the
characteristic frequency
of the mechanical system
and the carrier frequency.
Resonance between the
characteristic frequency
of a machine and the
output frequency of the
Inverter.
Vibration and hunting are occurring.
Influence by the slip
compensation function.
Motor vibrates excessively and does not rotate normally.
Motor Phase Interruption
126
Take the following actions to prevent noise.
• Lower the carrier frequency of the Inverter in n46.
The number of internal switching times is reduced, so noise can be
reduced to some extent.
• Install an Input Noise Filter.
Install an Input Noise Filter on the power input area of the Inverter.
• Install an Output Noise Filter.
Install an Output Noise Filter on the output area of the Inverter.
• Use metal tubing.
Electric waves can be shielded by metal. Therefore, enclose the
Inverter with a metal tube.
The Inverter performs internal switching. Therefore, a leakage current
flows through the Inverter. This leakage current may actuate the ground
fault interrupter, shutting the power off.
Use a ground fault interrupter with a high leakage-current detection value
(sensitivity amperage of 200 mA or more, operating time of 0.1 s or more)
or one with high-frequency countermeasures for Inverter use.
Reducing the carrier frequency value in n46 is also effective.
In addition, remember that a leakage current increases in proportion to the
cable length. Normally, approximately 5 mA of leakage current is
generated for each meter of cable.
There may be resonance between the characteristic frequency of the
mechanical system and the carrier frequency. If the motor is running with
no problems and the machinery system is vibrating with a high-pitched
whine, it may indicate that this is occurring. To prevent this type of
resonance, adjust the carrier frequency value in n46.
There may be resonance between the characteristic frequency of a
machine and the output frequency of the Inverter. To prevent this from
occurring, use the frequency jump function with the constants set in n49
through n51 to change the output frequency or install vibration-proof
rubber on the motor base to prevent the resonance of the mechanical
system.
The slip compensation function of the Inverter may influence the
characteristic frequency of the mechanical system to cause vibration or
hunting. In that case, increase the time constant in n67 for slip
compensation. The larger this time constant is, however, the slower the
response speed of the slip compensation function will be.
If one or two of the three phases of the motor are open, the motor will
vibrate excessively and will not rotate. Check that the motor is wired
correctly without any disconnection. The same phenomenon will occur if
the output transistor of the Inverter is open and damaged. Check the
balance of the Inverter's output voltage as well.
Chapter 8-2
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