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4) Harmonic suppression techniques
(2) Features of the FR-HC (high power factor converter)
The converter circuit of an inverter generates power harmonics, which may affect a generator, power
capacitor, etc. Power harmonics are different from noises and leakage currents in their sources,
frequency bands and transmission routes. Therefore, securely connect the high power factor converter
(FR-HC) with the FR series inverter, and refer to the inverter instruction manual on how to set the
parameters. The conversion factor of the high power factor converter is K5=0 for a self-excited, three-
phase bridge circuit:
Making the above settings suppresses power harmonics to conform to the harmonic suppression
guidelines published by the Ministry of International Trade and Industry.
• Power harmonic suppression effect
(Example) FR-HC-7.5K
(Environment) Load: 100%
Power factor: 1
No. Item Description
1
Reactor installation
(ACL, DCL)
Install a reactor (ACL) in the AC side of the inverter or a reactor (DCL) in its DC side or
both to suppress harmonic currents.
2
High power factor
converter (FR-HC)
Designed to switch the converter circuit on-off to convert an input current waveform into
a sine wave, the high power factor converter (FR-HC) suppresses harmonic current
considerably. The FR-HC is used with the standard accessories.
3
Installation of power
factor improving capacitor
When used with a series reactor, the power factor improving capacitor has an effect of
absorbing harmonic currents.
4
Transformer multi-phase
operation
Use two transformers with a phase angle difference of 30° as in - , - combination to
provide an effect corresponding to 12 pulses, reducing low-degree harmonic currents.
5AC filter
A capacitor and a reactor are used together to reduce impedance at specific
frequencies, producing a great effect of absorbing harmonic currents.
6 Active filter
This filter detects the current of 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 a harmonic current at a detection point, providing a great
effect of absorbing harmonic currents.
∆∆∆
[FR-HC not connected]
Phase voltage (100V/div)
Phase current
(50A/div)
[FR-HC connected]
Phase voltage (100V/div)
Phase current
(50A/div)