Other Wiring; Power Supply Harmonics - Mitsubishi Electric FR-E520 Instruction Manual

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 counter measures.
! ! ! ! The differences between harmonics and RF noises are indicated below:
Item
Normally 40th to 50th degrees or
Frequency
less (up to 3kHz or less)
Environment To wire paths, power impedance
Quantitative
Logical computation is possible
understanding
Generated Approximately proportional to
amount load capacity
Immunity of
Specified in standards for each
affected
device.
device
Examples of
Install a reactor.
safeguard
! ! ! ! Countermeasures
The harmonic current generated from the
inverter to the power supply differs according
to various conditions such as the wiring
impedance, whether
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.
Harmonics
a power factor
38
INSTALLATION AND WIRING
RF Noise
High frequency (several 10kHz to
1GHz 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.
NFB
Power factor Do not insert power
improving AC factor improving capacitor
reactor
Power factor
improving DC
reactor
Motor
IM