Power Supply Harmonics - Mitsubishi Electric FR-A820-00046 Instruction Manual

Precautions for use of the inverter
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 gen-
erator, 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 countermeas-
ure suppression techniques.
The differences between harmonics and noises
Item
Frequency
Location
Quantitative understanding
Generated amount
Affected equipment immunity
Countermeasure
Tab. 3-6:
Countermeasures
The harmonic current generated from the inverter to the input side differs according to various con-
ditions such as the wiring impedance, whether a reactor is used or not, and output frequency and out-
put current on the load side.
For the output frequency and output current, we understand that this should be calculated in the con-
ditions under the rated load at the maximum operating frequency.
Fig. 3-9:
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 exces-
sive 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 on the inverter input side or in the DC circuit.
FR-A800
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.
Differences between harmonics and noises
MCCB MC
Reduction of power supply harmonics
DC reactor
(FR-HEL)
P/+ P1
R X
R/L1 U
S Y
S/L2 V
T Z
T/L3 W
Inverter
AC reactor
Do not insert power
(FR-HAL)
factor improving capacitor
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.
M
3~
I002421E
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