Passive Harmonic Filters

  • Helps meet IEEE-519 requirements
  • Gurantees THDi performance of 8% Max at 50% load, 5% Max at full load
  • Meets the voltage and current distortion limits of IEEE-519
  • Saves energy by eliminating the wasted energy associated with harmonics, therefore reducing the true RMS KVA demanded from your power source.
  • Suitable for speed controllers or inverters
  • Reduces energy costs
  • Increases equipment reliability by absorbing transients and voltage surges
  • Increases equipments life by reducing heat associated with harmonic currents
  • Improves power factor
  • Reduces THD-V to meet power quality standards.


Most of the mentioned filtering techniques have common drawback of higher cost compared to Passive Filtering techniques. Consequently, the harmonic filtering techniques to a large extent are still the most commonly used techniques for current harmonics mitigation of 6-pulse front-end diode rectifier application.

We have developed an efficient Passive Filter, which can suit many such similar loads. Since all filter components are passive they are rugged, maintenance free, reliable and low cost. Moreover, the filter implementation procedure is relatively easy.

  • Powernac series Harmonic Filter for VFD’s are simple and effective way to control harmonics generated by VFD’s.
  • The filter design typically reduces current harmonic distortion (THD-I) to less than 5% at full load.
  • Powernac Filters offer much superior performance over other filtering methods including 12 pulse / 18 pulse harmonic reduction techniques.
  • They are suitable for wide range of applications.
  • Powernac Filter uses all passive components and there are no electronics circuits / hardware therefore it offers reliable and maintenance free operation for a very long period of time.
  • Powernac Filters improve power factor of load and network thus offering dual advantage of harmonic reduction with PF Correction.

Technical Specifications

Technology Pasive Broad Resonant
Type 3P 3W
Output Load Type 6 Pulse Variable Rectified
Supply Voltage 415V AC ± 10%, 3 Phase
Frequency 50Hz ± 1Hz
I/P Voltage Unbalance 1% Max
Max Source Impedance 6%
Min Source Impedance 1.5%
Duty Continuous
Operating Ambient Temperature -20 C to +50 C
Overload 150% for 1 minute duration with 10% Output voltage reduction of nominal voltage
Total Current Harmonic distortion @ THD-V <3% <9% at 30% Load
<8% at 50-60% Load
<8% at 60-90% Load
<5% at 90-100% Load
Protection IP20

Design Features

  • Uses fewer capacitors while maintaining 98% efficiency.
  • More consistent power factor across the load range.
  • Improves C/L ratio, which decreases potential resonance.
  • Lowers capacitance resulting in less voltage rise at no load, at PCC (Point of Common Coupling) and on the DC Bus.