APF Active Power Filter Cabinet

Junray Electrical APF Active Power Filter Cabinet is designed to eliminate harmonic pollution caused by non‑linear loads such as variable frequency drives, rectifiers, and UPS systems. It provides real‑time harmonic compensation across the 2nd to 50th harmonic orders, achieving a mitigation efficiency of ≥95% and reducing total harmonic distortion (THDi) to within the limits of GB/T 14549 and IEEE 519 standards. This protects transformers, cables, capacitors, and sensitive downstream equipment from overheating, premature aging, or failure. The cabinet is floor‑standing, rated IP4X, and built with multiple built‑in protections including overvoltage, undervoltage, overcurrent, and overtemperature safeguards. Suitable for manufacturing plants, chemical facilities, data centers, and large infrastructure projects.

Why does your factory urgently need dynamic management?

With the widespread use of non-linear loads such as frequency converters and rectification equipment, the harmonic pollution of the power grid has become increasingly severe. This not only causes transformers to overheat and accelerates the aging of cables, but may also lead to capacitor explosions, relay protection malfunctions and other serious accidents. The more direct economic losses come from the "harmonic fines" imposed by the power supply department. Traditional passive filters can only target specific frequencies and are prone to resonance with system impedance, causing secondary pollution. Our APF Active Power Filter Cabinet adopts advanced dynamic management technology. It is like a "purifier" for the power grid, capable of real-time monitoring of current waveforms, automatically identifying and generating compensating currents of equal amplitude and opposite direction to the harmonic amplitudes. This "using poison to counter poison" approach can completely eliminate the impact of harmonics, control the total harmonic distortion rate within the national standard range, and allow you to completely say goodbye to fines and the risk of equipment burning out.

Core advantage

The core value of this APF Active Power Filter Cabinet lies in its high dynamic response capability and high-precision control effect. Firstly, it has a full-range harmonic control capability, capable of filtering out more than 95% of harmonics, including common 5th and 7th harmonics, as well as higher-order harmonics ranging from 2nd to 50th. Secondly, it significantly improves power quality by controlling harmonics, reducing line losses, and increasing the effective load rate of transformers, which is equivalent to an expansion of the transformer capacity. More importantly, it can effectively protect sensitive downstream equipment, extending the service life of motors and frequency converters. For many factories, the electricity savings and penalty avoidance achieved in the first month after installing this equipment often cover a considerable portion of the equipment cost, resulting in an extremely high return on investment.

Junray Electrical's Commitment

As a seasoned manufacturer with international certifications such as ISO, CE, and CCC, Junray Electrical is well aware of the harshness of industrial environments. This APF Active Power Filter Cabinet adopts a floor-standing design and has a protection level of IP4X, suitable for various distribution room environments. The interior uses high-quality APF active filter modules, combined with standardized power and weak current separation wiring techniques, ensuring the electromagnetic compatibility and stability of the system. The equipment features powerful intelligent detection capabilities, which can automatically adapt to load changes without frequent manual adjustments. At the same time, we have built-in multiple protection mechanisms such as overvoltage, undervoltage, overcurrent, and overtemperature protection. In case of system abnormalities, it will automatically shut down and give an alarm. The dedicated cooling and ventilation design ensures that the modules remain calm and stable even during long periods of high-load operation.

Widely applicable scenarios

Our APF Active Power Filter Cabinet is widely used in places with extremely high requirements for power quality. It is indispensable as a "power grid guardian" in manufacturing plants with a large number of frequency converters, chemical plants equipped with rectification equipment, and data centers with high data density. For large infrastructure projects, it can also effectively manage the harmonic interference generated by construction equipment. Choosing Junray Electrical means choosing a partner who understands technology and values quality. We provide a full-process service from selection, installation to after-sales, ensuring that your power distribution system reaches the optimal state.

Technical Specifications

Case Study

This project involves a municipal secondary sewage treatment plant. Key loads include influent lift pumps, return pumps, aeration blowers, and sludge dewatering equipment. All equipment utilizes variable frequency drives (VFDs) and soft starters for speed control, representing a typical scenario involving high-intensity non-linear loads.

Issues Identified

The plant's original low-voltage power distribution system was equipped only with standard reactive power compensation capacitor banks and lacked harmonic mitigation equipment. Long-term operation resulted in various power quality issues that frequently disrupted continuous production, creating an urgent need for the installation of Active Power Filters (APFs) for comprehensive mitigation.

Severe harmonic distortion: On-site power quality testing revealed a Total Harmonic Distortion of Current (THDi) of 27.6% on the low-voltage side, with dominant characteristic harmonics at the 5th, 7th, 11th, and 13th orders—levels that far exceeded permissible limits.

Frequent capacitor bank failure: Reactive power compensation capacitors frequently suffered from bulging, dielectric breakdown, and tripping, rendering them unable to switch properly; the resulting low power factor posed a risk of financial penalties based on power factor adjustment charges.

Severe equipment overheating: Abnormal temperature rises were observed in low-voltage busbars, power cables, and transformers, accelerating cable insulation aging and creating a fire hazard.

Unstable automation systems: PLCs, instrumentation, and online monitoring equipment suffered from harmonic interference, leading to data fluctuations and abnormal readings, which occasionally caused false triggering of process interlocks.

Nuisance tripping of distribution cabinets: Harmonics caused excessive zero-sequence and distorted currents, leading to frequent nuisance tripping of low-voltage circuit breakers and earth leakage protection devices, thereby disrupting continuous sewage treatment.

Solution

Based on the load characteristics and harmonic test data, a 300A APF active filtering cabinet was installed in a centralized parallel configuration on the 0.4kV main busbar in the low-voltage distribution room. This setup employs a parallel connection to dynamically mitigate harmonics across all frequency ranges while simultaneously providing dynamic reactive power compensation and suppressing grid resonance. Equipment Specifications:

Model: Low-voltage Active Power Filter (APF-300A/380V)

Installation Location: 0.4kV low-voltage main distribution room

Compensation Method: Real-time parallel active mitigation

Mitigation Scope: Full-spectrum harmonics (2nd to 50th orders); simultaneous harmonic mitigation and dynamic reactive power compensation

Response Time: ≤5ms; compatible with dynamic fluctuating loads from variable-frequency drive (VFD) fans and pumps

Harmonic Compliance: System THDi reduced from 27.6% to below 8%

Results

Complete resolution of capacitor cabinet failures: Eliminated harmonic resonance interference; capacitors no longer bulge or trip; reactive power compensation system operates stably.

Significant reduction in equipment temperature rise: Heating issues in transformers, busbars, and cables were markedly improved; eliminated risks of long-term high-temperature degradation; extended the service life of power distribution equipment.

Stable automation control system: Harmonic interference completely eliminated; data from PLCs, sensors, and online monitoring instruments remained stable, with no erratic fluctuations or false interlock trips.

Improved power supply reliability: Completely resolved issues with nuisance tripping of low-voltage switches; ensured continuous, stable 24-hour operation of the wastewater treatment process; prevented production shutdowns.