RHF-Passive

RHF-5P and RHF-8P – highly efficient passive harmonic filters

The REVCON® harmonic filter RHF is passive filter, designed to reduce the harmonic distortion of a load fed by a 6-puls rectifier. This kind of load is very common in drive applications.

The REVCON RHF-5P/8P is a passive filter. It is not tuned to individual frequencies like an absorption circuit, but works like a bandstop filter, reducing all low harmonics up to the 200th significantly.

 
 

For a comparison, the circuit feedbacks of variable frequency drives and regen units are shown evaluated by the THiD (total harmonic distortion of the line current) at the nominal point of the electric rectifier/inverter in the following table:

 
Unchoked 6-pulse rectifierChoked 6-pulse rectifierChoked 6-pulse rectifier with RHF-8PChoked 6-pulse rectifier with RHF-5P
>80%~40%<8%<5%

The passive harmonic filter REVCON RHF- 5P and 8P is an effective, inexpensive and very efficient (>98.5%) action in order to reduce harmonic distortion of a drive system.

Advantages:

  • very compact size
  • THDi below 5%
  • output range 4kW to 630kW
  • high efficiency
  • user-friendly start-up, as no programming or settings are required
  • maintenance free!

Application

RHF-8P

<8% THDi

RHF-5P

<5% THDi

RHF-Hybrid

~1% THDi

RHF8P
Active
Scalable

Vaiable Frequency Drives – VFD

Yes

Yes

Yes

Yes

Water and wastewater treatment

Yes

Yes

Yes

Yes

HVAC

Yes

Yes

Yes

Yes

Pumps and Fans (VFD)

Yes

Yes

Yes

Yes

Industrial/ Factory Process (VFD)

Yes

Yes

Yes

Yes

DC charger

Yes*

Yes*

Yes

Yes

Buildings

Yes

Yes

Yes

Yes

Data Center (power supply)

No

No

Yes

Yes

IEEE 519-2014 requirement

Yes*

Yes

Yes

Yes

Marine

Yes

Yes

No

No

IEEE 519-2014 specified application

Yes

Yes

Yes

Yes

Electronically comutated / EC Motor

No

No

Yes

Yes

Non symetrical Load

No

No

No

Yes

Symetrical load multiple VFD

Yes

Yes

Yes

Yes

Symetrical load multiple equimpment

No

No

No

Yes

Displacement factor correction („pf“)

No

No

No

Yes

Unbalance compensation

No

No

No

Yes

Ideally all loads and sources have a pure sinusoidal current waveform. But unfortunately the true waveform of most equipment is very different. Nonlinear loads like for example the diode input bridge of a 6 pulse drive, are causing a distortion of the mains voltage. This distortion typically evaluated by the Total Harmonic distortion THD, evaluates frequencies from the 2nd up to the 40th harmonic. In a 50Hz Network this is the area between 100Hz and 2kHz.

The impact of the voltage distortion is diverse, and the most typical effect is overheat of transformer and PFC applications  (Capacitor banks). Underestimated impacts of harmonic distortion is the significantly reduced lifetime expectation of electrical  and mechanical equipment.

The Revcon Harmonic Filter (RHF) avoids the harmonic distortion of nonlinear loads and sources. The filter is not tuned to a specific frequency, but works like a bandwidth filter, reducing all frequencies up to the 50th harmonic. The RHF filter reduces the Total Harmonic Distortion of the current (THDi) to a level significantly below 5%. This is necessary to reach various standards, for e.g. IEEE 519-2014, who are getting more and more common.

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