Representative imagePassive Harmonic Filter
A passive harmonic filter is a line-side LCL network of reactors and tuned capacitors connected ahead of a non-linear load — typically a 6-pulse front-end diode rectifier in a VFD or DC drive — to reduce input current-harmonic distortion (THDi) and improve true power factor.
Overview
A passive harmonic filter is a line-side LCL network of reactors and tuned capacitors connected ahead of a non-linear load — typically a 6-pulse front-end diode rectifier in a VFD or DC drive — to reduce input current-harmonic distortion (THDi) and improve true power factor. ACE's design combines a series low-pass and a shunt high-pass section that acts as the harmonic source for the load's harmonic demand, cutting harmonics at the supply end so the filter can be installed close to the load and reduce I²R and skin-effect losses in the bus ducts. Because all components are passive, the filter is rugged, maintenance-free, reliable and low-cost, with no electronic control circuitry. Buyers choose it as the most economical route to IEEE-519 compliance on 6-pulse drives, with guaranteed THDi performance and over 97% efficiency.
Specifications
| Power/HP range | typically 5 HP to ~500 HP per unit; floor-mounted ranges extend to ~2,600 kVA for large AC VFD / DC SCR drives |
|---|---|
| Voltage class | LV 200-240 V / 380-480 V / 415 V / 575-690 V, 3-phase, 50/60 Hz |
| Topology | series low-pass + shunt high-pass (broadband LCL), tuned to dominant 5th/7th/11th/13th harmonics |
| Guaranteed THDi | 5% max at full load, 8% max at ~30-50% load |
| Efficiency | >97% |
| Configuration | 3P3W (balanced load) and 3P4W (corrects up to 25% unbalance) |
| Power factor | near-unity / >0.95 across load range; optional input inductor for operation below ~20% load |
| Enclosure | IP00 frame-mount (fits inside drive panel) up to IP20/IP54 cabinet |
| Cooling | natural air / forced-air convection |
| Applicable standards | IEEE-519, IEC 61000-3, IS 2026 / IEC 60076 (reactors) |
Applications
- Front-end six-pulse DC rectifiers
- Variable-frequency drives (VFD) and motor applications
- Automation equipment
- HVAC equipment using motor drives
- Waste-water / effluent treatment plants
- Battery chargers
Frequently asked questions
Do you build custom harmonic & electric filters to specification?
What quality standard does ACE Electromagnetics work to?
How soon will I get a response to a quote request?
Are the specifications shown on this page final?
Request a quote — Passive Harmonic Filter
Tell us your application and ratings. Our engineering team replies within one business day.
What we need to quote
- System voltage & frequency
- Load rating (kVA / A)
- Existing or target THD / standard (e.g. IEEE-519)
- Source & load type (drives, rectifiers…)
- Enclosure & mounting
- Application / end-use
Share what you have — we confirm the rest with you.
More in Harmonic & Electric Filters
Active Harmonic Filters
An active harmonic filter (AHF) is a shunt-connected IGBT PWM power converter that continuously…
Passive Broad Band Harmonic Filter
A passive broad-band harmonic filter (BBF) is a wide-bandwidth LC filter that attenuates…
Sine Wave Filters
A sine-wave (sine) filter is a low-pass LC filter fitted on the output of a PWM variable-frequency…