Other Wiring; Power Supply Harmonics - Mitsubishi Electric FR-E540 K-EC Series Instruction Manual

2.3 Other Wiring

2.3 Other wiring

2.3.1 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 measures.
The differences between harmonics and RF noises are indicated below:
Item
Normally 40 to 50th degrees,
Frequency
3kHz or less
To wire paths, power
Environment
impedance
Quantitative Logical computation is
understanding possible
Approximately proportional
Generated amount
to load capacity
Immunity of affected Specified in standards for
device each device.
Examples of
Install a reactor.
safeguard
Countermeasures
The harmonic current generated from the
inverter to the power
according to various conditions such as the
wiring impedance, whether a power factor
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
frequency.
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 information.
INSTALLATION AND WIRING
Harmonics
High frequency (several 10kHz to MHz
order)
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.
supply differs
NFB
Power factor
improving AC
reactor
32
RF Noise
Power factor
improving DC
reactor
Motor
IM
Do not insert power
factor improving capacitor
2