Power Supply Harmonics - Mitsubishi Electric F700 Instruction Manual

2.3.6

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.
The differences between harmonics and noises are indicated below:
Item
Frequency
Environment
Quantitative understanding
Generated amount
Affected equipment immunity
Suppression example
Measures
The harmonic current generated from the
inverter to the input side differs according to
various conditions such
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.
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.
Harmonics
Normally number 40 to 50 max.
(3kHz or less)
To-electric channel, power
impedance
Theoretical calculation possible
Nearly proportional to load capacity
Specified in standard per equipment
Provide reactor.
as the wiring
High frequency (several 10kHz to 1GHz order)
To-space, distance, wiring path
Random occurrence, quantitative grasping difficult
Depending on the current fluctuation ratio (larger as
switching is faster)
Different depending on maker's equipment
specifications
Increase distance.
DC reactor
(FR-HEL)
MCCB MC
R X
S Y
T Z
AC reactor
(FR-HAL)
Others
Noise
P P1
R U
S V IM
T W
Inverter
Do not insert power
factor improving capacitor.
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