Input Filter

In modern industrial automation systems, VFDs and power electronic devices generate high-frequency switching noise and harmonic disturbances during operation. These disturbances may affect nearby controllers, communication systems, sensors, and other sensitive equipment.

Dufew Electric Input Filter is installed in series between the power supply and the VFD or servo drive input terminals to reduce electromagnetic interference transmission paths between the drive system and the electrical network.

The filter adopts a multi-stage EMC filtering structure combining optimized magnetic components, capacitors, and damping design to suppress both common-mode and differential-mode interference across a wide frequency range.

Key design features include:

- Low-loss magnetic components for stable filtering performance

- Optimized capacitor network for EMC suppression

- Low leakage current design for compatibility with protection systems

- High insulation performance for industrial environments

- Flexible IP00/IP20 installation configurations

With reliable EMC performance and customizable electrical parameters, Dufew Input Filters help improve system stability in demanding industrial applications.

How Input Filter Improves VFD System Performance?

1. Reduce Conducted Electromagnetic Interference

VFD switching devices generate high-frequency noise that can travel through power cables and feed back into the power grid. The filter helps reduce conducted emissions, limit the transmission of high-frequency interference, improve EMC performance, and minimize disturbance to nearby electrical equipment.

2. Suppress Common-Mode and Differential-Mode Noise

Different interference paths require different filtering methods. The filtering structure combines common-mode suppression for noise between power lines and ground with differential-mode suppression for interference between conductors. This helps improve electromagnetic compatibility in complex industrial environments.

3. Improve Power Network Stability

Industrial power networks can be affected by voltage fluctuations, switching disturbances, and harmonic interference. By reducing the impact of these disturbances on drive systems, the filter helps maintain stable equipment operation and provides additional protection for sensitive electrical components.

4. Support Long Cable and Multi-Drive Applications

EMC issues can become more noticeable in systems with multiple drives or long motor cable arrangements. The design is suitable for multi-drive installations, long cable applications, high-density control cabinets, and industrial automation systems where consistent EMC performance is required.

Key Design Features

Three-Stage EMC Filtering Structure

The optimized three-stage structure provides attenuation across low-, mid-, and high-frequency ranges, helping reduce different types of electrical interference and maintain effective filtering performance under varying operating conditions.

Low Leakage Current Design

The grounding capacitor structure is optimized to limit unnecessary leakage current while maintaining compatibility with leakage protection devices. This supports stable operation in industrial electrical systems.

High Reliability Insulation System

The insulation system is designed for long-term industrial use, with line-to-line dielectric strength up to 1500VDC/60S, line-to-ground dielectric strength up to 2500VDC/60S, and insulation resistance of ≥100MΩ at 1000VDC.

Application Scenarios

Dufew Input Filter solutions are widely used in applications requiring improved EMC performance and electrical stability.

Technical Specifications

Manufacturing Capability & Quality Assurance

Dufew Electric specializes in industrial power electronics components including EMC filters, reactors, braking resistors, and customized electrical solutions.

Through controlled manufacturing processes and electrical performance testing, Dufew ensures reliable product quality for industrial applications.

Quality control includes:

- Component inspection

- Electrical performance testing

- Insulation resistance testing

- Withstand voltage testing

- Functional verification

Dufew continuously improves its quality management system and product standards.

Certifications and technical documents include:

- ISO 9001 Quality Management System

- CE certification

- Product test reports

- Customized technical documentation

Dufew supports OEM manufacturing, customized designs, and engineering cooperation for global customers.

Packaging & Delivery

Dufew provides export-oriented packaging solutions to protect electrical components during transportation.

Packaging includes:

- Moisture protection

- Shock-resistant fixing

- Reinforced packaging for large models

- Product identification labels

- Technical documents with shipment

Each filter is inspected before delivery to ensure compliance with customer requirements.

FAQ

Q1: What is the purpose of an Input Filter in a VFD system?

It helps reduce electromagnetic interference generated during VFD operation, improve EMC performance, and protect electrical components from external power disturbances.

Q2: Where should this filter be installed?

It is installed between the power supply and the VFD or servo drive input terminals to reduce interference transmission through the power network and improve system stability.

Q3: What cable length can Dufew products support?

Depending on installation conditions, Dufew solutions can support shielded cables up to 400 meters and unshielded cables up to 300 meters, helping maintain stable filtering performance in long-distance applications.

Q4: Can Dufew customize EMC filtering solutions?

Yes. Dufew provides customized solutions including voltage rating, current capacity, filtering parameters, mechanical dimensions, and installation structures according to different application requirements.

Customized EMC Filtering Solutions from Dufew Electric

Dufew Electric provides customized Input Filter solutions for VFD systems, servo drives, and industrial automation applications.

With professional engineering capability, reliable manufacturing processes, and strict quality control, Dufew helps customers improve EMC performance, reduce electrical interference, and achieve stable long-term operation.