Power Supply Harmonics - Mitsubishi Electric FR-E700 Series Instruction Manual

Electromagnetic compatibility (EMC)
3.8.3

Power supply harmonics

The inverter may generate power supply harmonics from its converter circuit to affect the power gen-
erator, 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.
Item
Frequency
Environment
Quantitative understanding
Generated amount
Affected equipment immunity
Suppression example
Tab. 3-23: Differences between harmonics and noises
● 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
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 over current 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.
3 - 50
Harmonics
Maximum 50 (≤ 3kHz)
To electric channel, power impedance
Theoretical calculation possible
Nearly proportional to load capacity
Specified in standard per equipment
Provide reactor
Power
supply
operating frequency
DC reactor
(FFR-HEL-(H)-E)
Inverter
AC reactor
(FR-BAL-B)
Noise
Several 10kHz to 1GHz
To-space, distance, wiring path
Random occurrence, quantitative grasp-
ing difficult
Depending on the current fluctuation
ratio (larger as switching is faster)
Different depending on maker's equip-
ment specifications
Increase distance
.
M
3~
Do not insert power
factor improving capacitor
Wiring
I002049E