Power Supply Harmonics - Mitsubishi Electric FR-A802-P Instruction Manual

3.2

Power supply harmonics

3.2.1
Power supply harmonics
The inverter 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.
• The differences between harmonics and noises
Item
Frequency
Environment
Quantitative understanding
Generated amount
Affected equipment immunity
Countermeasure
• Countermeasures
The harmonic current generated from the inverter 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.
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.
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.
PRECAUTIONS FOR USE OF THE INVERTER
Power supply harmonics
Noise
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.
∗1
DC reactor
R/L1 U
S/L2 V
T/L3 W
Inverter/
Do not insert power
converter
factor improving capacitor.
unit

The converter unit is equipped with the DC reactor.
M
3
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