Overview Of Harmonic Suppression Measures - Mitsubishi Electric FATEC FR-A800 Manual

7
REVIEW OF INSTALLATION ENVIRONMENT
7.1.5

Overview of harmonic suppression measures

The following table lists the basis and characteristics overview of the methods to suppress and
absorb harmonics.
No. Item
Reactor for inverter
1)
(FR-HAL, HEL)
High power factor converter
2)
(FR-HC2)
Power factor improving static
3)
capacitor
Transformer multi-phase
4)
operation
5) AC filter
6) Active filter
 The countermeasures above are effective in the following order:
● For suppression effect: 6) or 2) → 5) → 4) → 3) → 1)
● For cost: 1) → 2) → 3) → 4) → 5) → 6)
7.1 Power supply of inverter (harmonics and instantaneous power failure)
Description
Connect an AC reactor on the power
supply side of the inverter or/and a DC
reactor on the DC side of the inverter to
increase the circuit impedance and
suppress the harmonic current.
The converter switches the converter
section ON/OFF to reshape an input
current waveform into a sine wave, greatly
suppressing harmonics. Connect it to the
DC area of an inverter.
The power factor improving capacitor has
a small impedance for high frequency
components and can absorb the harmonic
current when used with a reactor
connected in series. This capacitor can be
installed in either of the high or low
voltage side.
When two or more transformers are used,
connecting them with a phase angle
difference of 30° as in combinations of Y
to  and  to  will cause a timing shift
that suppresses peak current, resulting in
an effect equivalent to 12 pulses.
As in a power factor improving capacitor, a
capacitor and reactor connected in series
are used together to reduce the
impedance for a specific frequency
(ordinal number). The harmonic current is
absorbed greatly.
This filter detects the current in a circuit
generating a harmonic current and
generates a harmonic current equivalent
to a difference between that current and a
fundamental wave current to suppress the
harmonic current at the detection point.
Effect, etc.
Harmonic current is suppressed to
approximately half.
Harmonic current is suppressed to
almost zero.
The absorbing effect is greater in the low
voltage side.
Even if the capacities of the combinations
of Y to  and  to  are different, the
effect equivalent to 12 pulses is expected
for the smaller one. Thus, harmonic
current can be suppressed to
approximately half.
Current is greatly suppressed.
(The requirements of the guideline can
be satisfied.)
Current is greatly suppressed.
(The requirements of the guideline can
be satisfied.)
Since this filter corrects the whole
waveform, a power factor can be
improved.
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