Chapter 7 Troubleshooting |VFD-B Series
7-10 Revision July 2008, BE16, SW V4.08 & V5.00
7.15 Affecting Other Machines
AC motor drive may affect the operation of other machine due to many reasons. The solutions are
as follows.
High Harmonic at Power Side
If there is high harmonic at power side during running, the improved methods are:
1. Separate power system: use transformer for AC motor drive.
2. Use reactor at the power input terminal of AC motor drive or decrease high harmonic by
multiple circuit.
3. If phase lead capacitors are used (never on the AC motor drive output!!), use serial
reactors to prevent capacitors damage from high harmonics.
serial reactor
phase lead capacitor
Motor Temperature Rises
When the motor is induction motor with ventilation-cooling-type used in variety speed operation,
bad cooling will happen in the low speed. Therefore, it may overheat. Besides, high harmonic is in
output waveform to increase copper loss and iron loss. Following measures should be used by
load situation and operation range when necessary.
1. Use the motor with independent power ventilation or increase the horsepower.
2. Use inverter duty motor.
3. Do NOT run at low speeds for long time.
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