Power Supply Harmonics - Mitsubishi Electric FR-CC2-N Series Instruction Manual

3.2

Power supply harmonics

3.2.1 Power supply harmonics
The inverter or the converter unit may generate power supply harmonics from its converter circuit to affect the power generator,
power factor correction capacitor, etc. Power supply harmonics are different from noise and leakage currents in source,
frequency band and transmission path. Take the following countermeasure suppression techniques.
• Differences between harmonics and noises
Item
frequency
Location
Quantitative understanding
Generated amount
Affected equipment immunity
Countermeasure
• Countermeasures
The harmonic current generated from the inverter or the converter unit to the input side 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, we understand that this should be calculated in the conditions under the rated
load at the maximum operating frequency.
MCCB MC
Power
supply
*1 The converter unit (FR-CC2) has a built-in DC reactor.
NOTE
• The power factor improving capacitor and surge suppressor on the inverter output side may be overheated or damaged by the
harmonic 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.
For power factor improvement, install a reactor in the DC circuit of the inverter or the converter unit.
Harmonics
Normally 40th to 50th degrees or less (3
kHz or less).
To-electric channel, power impedance.
Theoretical calculation possible.
Nearly proportional to the load capacity.
Specified by standards per equipment.
Provide a reactor.
∗1
DC reactor
R/L1 U
S/L2 V M
T/L3 W
Inverter/
Do not insert power
converter
factor improving capacitor.
unit
High frequency (several 10 kHz to 1 GHz order).
To-space, distance, wiring path.
Random occurrence, quantitative grasping difficult.
Changes with the current variation ratio. (Gets
larger as switching speed increases.)
Different depending on maker's equipment
specifications.
Increase distance.
3. PRECAUTIONS FOR USE OF THE CONVERTER UNIT
3.2 Power supply harmonics
Noise
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