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Active Harmonic Filters
2 Series · 10 Models
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Active Harmonic Filters Overview
Active Harmonic Filters (APF), also called active power filters, measure the load current and inject an equal-and-opposite current to cancel harmonics at the point of common coupling. QDTB APF systems are rated 100–300 A at 400 V or 690 V and reduce total harmonic current distortion (THDi) to below 5%, protecting transformers, cables and capacitor banks while improving power quality and power factor.
Available Series
Modular APF Series
The modular active power filter (APF) uses rack-mounted power modules that can be paralleled to build the required compensation current. Rated 100–300 A per module at 400 V or 690 V, it measures the load current and injects a phase-opposite current to cancel harmonics, reducing total harmonic current distortion (THDi) to below 5% and improving power factor at the point of common coupling.
Cabinet APF Series
The cabinet active power filter (APF) packages the full compensation rating in a single floor-standing enclosure for central installation at a main switchboard or PCC. Rated 100–300 A at 400 V or 690 V, it cancels harmonics, reduces THDi to below 5%, corrects power factor and relieves transformers and cables of harmonic loading.
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| Base price (interpolation) | $8,750 |
| × Product factor | ×1.0000 |
| × Country factor | ×1.0000 |
| × Copper-linked factor | ×1.0000 |
| + Options / accessories | $0 |
Complete equipment — no winding copper linkage
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Application Scenarios
Data Centers
Mitigates harmonics from UPS and switch-mode power supplies to protect transformers and switchgear.
Industrial VFD Loads
Cancels harmonics from variable frequency drives, welders and rectifiers.
Commercial Buildings
Improves power quality for LED lighting, HVAC and lift drives.
Water & Pumping Stations
Contains harmonics from soft-starters and pump VFDs.
Technical Advantages
THDi < 5%
Closed-loop cancellation reduces total harmonic current distortion to below 5%.
Modular & Cabinet Options
Rack-mounted modules for scalability or single floor-standing cabinets.
100–300 A Ratings
Sized for individual circuits up to central main-switchboard compensation.
400 V / 690 V Systems
Low-voltage design for industrial and commercial distribution.
FAQ - Active Harmonic Filters
How does an active harmonic filter work?
What harmonics can an APF compensate?
Is an APF the same as a capacitor bank?
How do I size an active harmonic filter?
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All specifications and dimensions can be customized upon request