Mitsubishi Electric FR-D720S SC EC, Инструкция по эксплуатации, Страница: 87 / 512

Wiring Electromagnetic compatibility (EMC)
FR-D700 SC EC 3 - 51
3.7.3 Power supply harmonics
The inverter may generate power supply harmonics from its converter circuit to affect the power
generator, power 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.
●
Measures
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 they should be calculated
in the conditions under the rated load at the maximum operating frequency.
Item Harmonics Noise
Frequency
Maximum 50 (
≤
3kHz)
Several 10kHz to 1GHz
Environment To electric channel, power impedance To-space, distance, wiring path
Quantitative understanding Theoretical calculation possible Random occurrence, quantitative
grasping difficult
Generated amount Nearly proportional to load capacity Depending on the current fluctuation
ratio (larger as switching is faster)
Affected equipment immunity Specified in standard per equipment Different depending on maker's equip-
ment specifications
Suppression example Provide reactor Increase distance
Tab. 3-24: Differences between harmonics and noises
I002049E
Fig. 3-41: Reduction of power supply harmonics
b
CAUTION:
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 on the inverter input side or in the DC circuit.
Power
supply
AC reactor
(FR-BAL-B)
DC reactor
(FFR-HEL-(H)-E)
M
3~
Inverter
Do not insert power
factor improving capacitor
MCCB MC