Power Supply Harmonics - Mitsubishi Electric FR-V500 Instruction Manual

1.6.6

Power supply harmonics

Power supply harmonics may be generated from the converter section of the inverter, affecting the power supply
equipment, power capacitors, etc. Power supply harmonics are different in generation source, frequency and
transmission path from radio frequency (RF) noise and leakage currents. Take the following measures.
The differences between harmonics and RF noises are indicated below:
Item
Frequency
Environment
Quantitative understanding
Generated amount
Immunity of affected device
Examples of safeguard
Safeguard
The harmonic current generated from the inverter
to the power supply differs according to various
conditions such as the wiring impedance, whether
a reactor is used or not, and output frequency and
output current on the load side.
For the output frequency and output current, the
adequate method is to obtain them under rated
load at the maximum operating frequency.
CAUTION
The power factor improving capacitor and surge suppressor on the inverter output side may be
overheated or damaged by the high frequency components of the inverter output. Also, since an
excessive current flows in the inverter to activate overcurrent protection, do not provide a capacitor and
surge suppressor on the inverter output side when the motor is driven by the inverter. To improve the
power factor, insert a reactor on the inverter's primary side or in the DC circuit.
Harmonics
Normally 40 to 50th degrees (3kHz or less) High frequency (several 10kHz to 1GHz order)
To wire paths, power impedance
Logical computation is possible
Approximately proportional to load
capacity
Specified in standards for each device.
Install a reactor.
Across spaces, distance, laying paths
Occurs randomly, quantitative understanding is
difficult.
According to current fluctuation rate (larger with
faster switching)
Differs according to maker's device specifications.
Increase the distance.
DC reactor
MCCB
AC reactor
19
Others
RF Noise
IM
Motor
Do not insert power factor
improving capacitor.
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