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We offer a comprehensive portfolio including resistors, braking units, reactors, power filters, and transformers, with full customization options to meet diverse application requirements.
Dufew Electric Harmonic Filter is designed for VFD systems and other nonlinear loads that generate harmonic currents during operation. Installed on the input side of the drive system, it uses a tuned LC circuit with filter reactors, power capacitors, and non-inductive damping resistors to reduce selected low-order harmonics and improve power quality. The typical target harmonics include the 5th, 7th, 11th, and 13th orders, with the final configuration determined by system voltage, load characteristics, harmonic spectrum, and required filtering performance.
Typical performance parameters include THDi <10% at full load, THDv <5%, power factor above 0.98, temperature rise ≤80K, noise level ≤65dB, and dielectric strength up to 3000VAC, subject to the selected model and operating conditions.
VFDs, converters, rectifiers, and other nonlinear loads can generate harmonic currents during AC-DC conversion and switching operation. When harmonic levels become excessive, they may increase transformer and cable losses, cause additional heating, reduce power factor, and affect the stability of sensitive electrical equipment.
For industrial power networks with multiple nonlinear loads, appropriate harmonic control helps maintain stable electrical conditions and reduce the impact of harmonic currents on the distribution system.
The reactor and capacitor parameters are matched according to the system and harmonic characteristics to create a low-impedance path at selected harmonic frequencies. This allows harmonic currents to be diverted through the filter while maintaining normal fundamental-frequency operation.
Non-inductive damping resistors are incorporated into the filtering circuit to control resonance between the filter, grid impedance, and nonlinear loads. This helps limit harmonic amplification and reduce excessive current stress on the filtering components during continuous operation.
Stable filtering performance depends on the proper coordination of reactor inductance, capacitor capacity, damping resistance, and heat dissipation. Dufew adjusts these parameters according to the electrical rating and operating conditions to maintain reliable performance under continuous industrial loads.
Filter selection should be based on the actual electrical characteristics of the installation rather than rated power alone. Dufew evaluates system conditions such as voltage, current, VFD capacity, harmonic spectrum, required THDi, and installation environment when developing a suitable configuration.
Engineering support can cover harmonic analysis, filter parameter calculation, electrical configuration, mechanical structure, and application guidance. Customers can provide harmonic measurement data, single-line diagrams, equipment specifications, or operating conditions for technical evaluation.
The tuned filtering circuit reduces characteristic harmonic currents generated by VFDs and other nonlinear loads, helping lower current waveform distortion and reduce harmonic circulation through transformers, cables, and other distribution equipment.
By addressing harmonic current and reactive power effects, the filter can help improve power factor, reduce reactive power demand, and lower losses within the electrical distribution system.
Reducing harmonic distortion can improve the operating conditions of transformers, distribution equipment, industrial automation systems, and other electrical loads, particularly in installations with a high proportion of nonlinear equipment.
| Selection Factor | Consideration |
|---|---|
| System Voltage | 220V / 380V / 690V / 1140V |
| Load Type | VFDs, converters, nonlinear industrial loads |
| Rated Current | Based on connected equipment capacity |
| Harmonic Condition | THDi measurement or system analysis |
| Performance Target | Required harmonic reduction level |
| Installation Condition | Cabinet space and environmental requirements |
Dufew can recommend suitable filter configurations according to actual application requirements.
Dufew Harmonic Filter solutions are suitable for industrial power systems where harmonic distortion affects equipment performance.
| Application | Main Requirement |
|---|---|
| VFD systems | Reduce harmonic current distortion |
| Multiple drive systems | Improve power network stability |
| Industrial automation | Maintain reliable electrical operation |
| Elevators | Reduce harmonic impact during frequent acceleration |
| Cranes and lifting equipment | Support dynamic load operation |
| UPS systems | Improve power quality |
| Battery charging systems | Reduce harmonic influence |
| Induction heating equipment | Improve electrical compatibility |
| Renewable energy systems | Support stable grid connection |
Example: HFL-4 3 1-0490
| Code | Description |
|---|---|
| HFL | Dufew Electric Harmonic Filter Series |
| 4 | Voltage Level (2=220V, 4=380V, 6=690V) |
| 3 | Phase Number (3=Three-phase, 1=Single-phase) |
| 1 | Filter Configuration |
| 0490 | Rated Current (0490=490A) |
| Parameter | Specification |
|---|---|
| Rated Voltage | 220VAC / 380VAC / 690VAC / 1140VAC |
| Frequency | 50Hz / 60Hz |
| Carrier Frequency | 2kHz - 6kHz |
| Rated Current | 5A - 1200A |
| Filtering Performance | THDi <10%, THDv <5% |
| Power Factor | PF >0.98 at full load |
| Overload Capability | 120% rated current for 30 minutes |
| Temperature Rise | ≤80K |
| Noise Level | ≤65dB |
| Dielectric Strength | 3000VAC / 50Hz / 10S |
| Insulation Resistance | ≥100MΩ |
| Protection Grade | IP00 / IP22 |
| Insulation Class | Class F (155℃) |
| Standards | IEC61000 / GB/T14549-1993 |
Dufew Electric specializes in industrial power electronics components, including harmonic filters, reactors, braking resistors, transformers, and customized electrical solutions.
For harmonic filtering products, Dufew focuses on:
- Reactor manufacturing and parameter matching
- Capacitor selection and integration
- Resonance characteristic verification
- Electrical safety testing
- Performance validation
Each product undergoes inspection including:
| Inspection Item | Purpose |
|---|---|
| Insulation resistance testing | Verify insulation reliability |
| Dielectric withstand testing | Confirm electrical safety |
| Electrical parameter testing | Ensure design performance |
| Temperature rise testing | Verify thermal capability |
| Final inspection | Confirm manufacturing quality |
Dufew supports:
- OEM manufacturing
- Customized harmonic solutions
- Engineering cooperation
- Project-based technical support
Available documentation includes ISO quality management certification, CE certification, and product test reports.
Dufew provides export-standard packaging solutions for industrial electrical products.
Packaging includes:
- Moisture protection
- Shock-resistant fixing
- Reinforced wooden cases for heavy models
- Product identification labels
- Technical documents with shipment
Each unit is inspected before delivery to ensure compliance with customer specifications.
| Comparison | Harmonic Filter | EMI Input Filter |
|---|---|---|
| Main Function | Reduce harmonic distortion and improve power quality | Suppress electromagnetic interference |
| Target | 5th / 7th / 11th / 13th harmonics | High-frequency conducted and radiated noise |
| Circuit Design | Tuned LC circuit with damping resistor | EMI filtering network |
| Application | VFD systems and nonlinear loads | EMC-sensitive electronic equipment |
| Main Benefit | Lower THDi and improved grid stability | Reduced electrical noise |
A typical filtering circuit uses reactors, capacitors, and damping resistors. These components work together to create a tuned path for selected harmonic frequencies and help improve overall power quality.
Selection depends on system voltage, rated current, VFD capacity, harmonic characteristics, THDi requirements, and installation conditions. Dufew provides recommendations based on the specific application and operating requirements.
Yes. Dufew can evaluate harmonic measurement results together with system parameters and required filtering performance to determine a suitable configuration for the application.
The former is mainly used to reduce low-order harmonic currents generated by nonlinear loads, while an EMI filter primarily addresses high-frequency interference caused by switching devices.
Dufew Electric provides customized solutions for VFD systems, industrial automation equipment, and power conversion applications. With engineering experience, controlled manufacturing processes, and quality inspection procedures, Dufew supports filter selection, parameter matching, and application-specific configurations based on actual system requirements.
Contact Dufew Electric for product specifications, technical evaluation, and customized project support.
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No. 364, Kangyang Road, Huangdai Town, Xiangcheng District, Suzhou City, Jiangsu Province, China
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