Other Wiring; Power Harmonics - Mitsubishi Electric FR-CV-7.5K Instruction Manual

Other wiring

2.4 Other wiring

2.4.1

Power harmonics

Power harmonics may be generated from the power regeneration common converter, affecting generators, power
capacitors, etc. Power harmonics are different in generation source, frequency and transmission path from radio
frequency (RF) noise and leakage currents.
The differences between harmonics and RF noise indicated below:
Item
Frequency
Environment
Quantitative understanding
Generated amount
Immunity of affected device
Safeguard
The harmonic current generated from the power regeneration common converter to the power supply differs
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 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.
NFB
Do not insert power factor
Note: A power factor improving capacitor or surge suppressor on the inverter's output 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. Do not use the power factor improving AC reactor (FR-BAL)
since using it may degrade the power regeneration function.
Harmonics
Normally 40th to 50th degrees or
less, (up to 3kHz or less)
To wire paths, power impedance
Logical computation is possible
Approximately proportional to load
capacity
Specified in standards for each
device.
Dedicated
Power factor
improving AC
stand-alone
reactor
reactor
improving AC reactor
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.
Do not insert power factor
improving DC reactor
Power factor improving
DC reactor
Power regeneration
Inverter
common converter
Do not insert power factor
improving capacitor
24
RF Noise
Motor
IM