Liebert AF3


Liebert AF3
Next Generation Active Harmonic Filter


Liebert AF3 latest technology to eliminate harmonic injected into the mains supply by non linear loads, as well supplies inductive power demanded by the load, so as to correct input power factor to near unity.

 Current harmonic elimination is achieved by sensing load current and extracting harmonic current signal. This and the reactive current signal, together are used to generate a reference for the controlled current source connected at the PCC (point of common connection) of source and load.This results in mains supplying only real power for the load and reactive and harmonics being sourced from the AF3.This is carried out dynamically, so that any change in the load pattern or its nature is immediately responded without any manual intervention.

In the following example first figure shows the recorded input current waveform of a six pulse thyristorised rectifier. Bottom figure shows considerable improvement in the waveform due to AF3 connected in shunt. One is with only harmonic correction and the other is with power factor and harmonic correction.

  • Synchronous Rotating Reference Frame principle
  • 32 bit, DSP control
  • PF compensation, leading as well as lagging
  • Load Balancing
  • Employees high speed IGBTs in power circuit
  • Internal CAN Communication
  • Closed loop active filter with source current sensing
  • High attenuation up to 96 % of individual harmonics
  • Programmable selective harmonic elimination
  • Required PF can be set from 0.7 to unity
  • Selection between PF and harmonic compensation
  • Remote monitoring and diagnosis
  • Self current limiting, under overloading condition
  • Automatic current limit modification with respect to ambient temperature
  • Alarm log with date and time stamp for fault diagnosis
  • User friendly PC Interface
  • CE Marking

Value to customer

  • Improves reliability of the electrical system, reduces cable and transformer losses.
  • Better utilization of distribution Transformer and Generator.
  • Increases efficiency, capacitor life, PF, uptime.
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