E6581528
A-22
1
If power supply distortion is not negligible
If the power supply distortion is not negligible because the inverter shares a power distribution line with other
systems causing distorted waveforms, such as systems with thyristers or large-capacity inverters, install an input
reactor to improve the input power factor, to reduce higher harmonics, or to suppress external surges.
Disposal
If an inverter is no longer usable, dispose of it as industrial waste.
1.5.3 What to do about the leak current
Caution
Current may leak through the inverter's input/output wires because of insufficient electrostatic capacity on the motor with bad
effects on peripheral equipment. The leakage current's value is affected by the carrier frequency and the length of the
input/output wires. Test and adopt the following remedies against leakage current.
(1) Effects of leakage current across ground
Leakage current may flow not just through the inverter system but also through ground wires to other systems.
Leakage current will cause earth leakage current breakers, leakage current relays, ground relays, fire alarms and
sensors to operate improperly, and it will cause superimposed noise on the CRT screen or display of incorrect current
values during current detection with the CRT.
Leakage current path across ground
Power supply
inverter
inverter
Remedies:
1. Reduce PWM carrier frequency.
The setting of PWM carrier frequency is done with the parameter
.
2. If there is no radio-frequency interference or similar problem, detach the built-in noise filter capacitor.
⇒ Refer to Section 1.4.3
3. Use high frequency remedial products for earth leakage breakers.
If you use equipment like this, there is no need to reduce the PWM carrier frequency.
4. If the sensors and CRT are affected, it can be remedied by reducing the PWM carrier frequency described in
1 above, but if this cannot be remedied because of the increase in the motor's electric magnetic noise,
please consult with your supplier.
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