Power supply harmonics
Power supply harmonics may be generated from the converter section of the inverter,
affecting the power supply equipment, power capacitor, etc. Power supply harmonics
are different in generation source, frequency band and transmission path from radio
frequency (RF) noise and leakage currents. Take the following counter measures.
! ! ! ! The differences between harmonics and RF noises are indicated below:
Normally 40th to 50th degrees or
less (up to 3kHz or less)
To wire paths, power impedance
Logical computation is possible
Approximately proportional to
Specified in standards for each
Install a reactor.
! ! ! ! Countermeasures
The harmonic current generated from the
inverter to the power supply differs according
to various conditions such as the wiring
improving reactor is used or not, and output
frequency and output current on load side.
For the output frequency and output current,
the adequate method is to obtain them under
rated load at the maximum operating
Note: A power factor improving capacitor and surge suppressor on the inverter's
output side may overheat or be damaged due to the harmonics of the inverter
output. Also, when an overcurrent flows in the inverter, the overcurrent
protection is activated. Hence, when the motor is driven by the inverter, do not
install a capacitor or surge suppressor on the inverter's output side. To improve
the power factor, insert a power factor improving reactor in the inverter's input
or DC circuit. For details, refer to the FR-A500/E500 series technical
INSTALLATION AND WIRING
High frequency (several 10kHz to
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
Increase the distance.
Do not insert power
factor improving capacitor