Active Harmonic Filter (AHF)

Active harmonic filters are parallel filters (which means the Load current doesn’t go through the filter) that are used to reduce or mitigate, harmonics to tolerable levels as defined by IEEE-519. These are Active Front End IGBT based topologies connected to the mains, to filter (or clean) the current wave by injecting inverse currents to cancel out the undesired harmonic components. Depending on the harmonic content, the load variation and budget it might be better to go in for a Hybrid Filter.

Active filters can be parallel to achieve the compensation required. Trinity active harmonic filters provide a solution for real-time cancellation of harmonic distortions created by non-linear loads to ensure compliance with IEEE 519, G5/4 and other power quality standards and recommendations. Trinity active harmonic filters are a versatile solution, easily tailored to deliver power factor improvement, voltage variation control, flicker mitigation and load balancing


Rated Voltage AC 400V, AC 690V



Input Voltage Range AC 400V : AC 308V~480V
AC 690V : AC 432V~880V
Electric Connection AC 400V : 3P3W/3P4W
AC 690V : 3P3W
Rated Frequency 50Hz +/- 10%
Input Voltage THD Range  <15%
Rated Current per Module AC 400V : 60Amp, 90Amp, 150Amp
AC 690V : 60Amp
Rated Current per Cabinet AC 400V : 50~500Amp (module combination)
AC 690V : 60~300Amp (module combination)
Redundancy Each module is an independent filtering system
Harmonic Elimination Range AC 400V : 2rd ~ 50th order (Selectable)
AC 690V : 2rd ~ 31st order (Selectable)
Harmonic Filtering Degree 0 ~ 100% programmable per harmonic in Ampere value
Harmonic Filtering Performance  Filter up to 98% harmonics at rated load, THDv<3%, THDi<5% after filtering
Reactive Power Compensation Both inductive and capacitive reactive power
Imbalance Correction Capability AC 400V : Mitigate negative and zero sequence
AC 690V : Mitigate negative sequence
Full Response time <20ms
Instant Response time <100us
Thermal Loss <3% of APF rated capacity (kVA)
Output Current Limitation Automatic (100% rated capacity)
Parallel Expansion(System) AC 400V : Up to 5 Racks(5 modules per cabinet)
AC 690V : Up to 5 Racks(5 modules per cabinet)
Switching Frequency AC 400V - 60A, 90A : 20kHz
AC 400V - 150A : 20kHz
AC 690A : 20kHz
Instant Response time DSP control
Thermal Loss Modbus Protocol, RS232/485
Output Current Limitation PQC Monitor Software (Optional)



IP Grade of Cabinet IP20, IP30 or customization
Cooling method Forced air cooling
Noise Level AC 400V : < 65dB(A) @1m (Module)
AC 690V : < 70dB(A) @1m (Module)



Ambient Temperature -10~50 0C
Relative Humidity  0~95%
Altitude <1000m Rated Capacity,
1000-2000m (derating 1% per 100m)


  • Multifunctional: Harmonic, reactive power We do not have unbalance compensation so far.
  • High harmonic filtering rate: Up to 98%.
  • Excellent imbalance correction: Both negative and zero sequence, mitigates neutral current.
  • Wide input voltage & frequency range, adapts to tough electrical environments.
  • Low thermal loss (≤3% of rated APF kVA), efficiency ≥ 97%.
  • High stability: Infinite impedance to grid, avoids harmonic resonance problems.
  • Flexible application: Modular design, embedded in standard or customized cabinet.
  • Easy installation and maintenance: Plug-in installation for APF module replacement and expansion.
  • Wide capacity range: 50A~150A for a single cabinet, up 10 cabinets in parallel.
  • Environmental adaptability: -10~50°C temperature, compatible with diesel generator.
  • Complete protection: Grid Over/Under voltage, APF over current, over temperature, and more.
  • All faults are recorded in the event log, which is convenient for failure analysis.
  • Excellent reactive compensation: High speed, Precise (-0.99≤PF≤0.99), Step less, Bi-directional (capacitive and inductance) compensation.