High-frequency and High-voltage Power Supply

DeFa Environmental Equipment manufactures high-frequency high-voltage power supplies for industrial electrostatic and plasma applications. These High-frequency and High-voltage Power Supply convert three-phase AC input into regulated DC output at voltages from 1 kV to 120 kV, with power ratings from 1 kW to 200 kW in a single chassis, and higher power available through parallel configurations.

The key technical difference from conventional 50/60 Hz line-frequency transformers is the switching frequency. We operate between 20 kHz and 50 kHz, using an LLC resonant topology with DSP control. This allows us to use much smaller ferrite-core transformers instead of large iron-core units, and achieve conversion efficiency above 95% across most of the load range. In practical terms, that means 20% to 30% lower energy consumption for the same output power compared to older transformer designs.

Functions & Advantages Description

Operating Principles

The High-frequency and High-voltage Power Supply rectifies AC input into DC, then switches it at high frequency through an inverter stage. The high-frequency AC is stepped up by a compact ferrite transformer, then rectified and filtered to produce the final DC output.

The DSP continuously adjusts switching frequency to maintain optimal operation under varying load and line conditions. This closed-loop regulation responds to changes in microseconds. Users can select from three control modes: constant voltage, constant current, or constant power. For electrostatic precipitators, constant current is typical because it maintains stable corona even when dust loading fluctuates. Plasma reactors usually run in constant voltage to keep discharge conditions stable.

Output Performance

Output ripple is below 1% peak-to-peak at full load. In an electrostatic precipitator, low ripple means more consistent corona current and better collection efficiency without excessive sparking. For plasma VOCs treatment, it results in stable discharge and more predictable oxidation rates.

Voltage regulation accuracy is within ±0.5% of setpoint, and current regulation within ±1%. The fast response time—typically under 100 microseconds—helps suppress sparkover in ESP applications, which reduces electrode wear and extends maintenance intervals.

Protection Systems

We've built in comprehensive protection for both the power supply and the connected load. Standard functions include overvoltage, overcurrent, short-circuit, input phase loss, and overtemperature shutdown.

Arc detection deserves special mention. In electrostatic precipitators, sparking is frequent and normal to some degree. But sustained arcs can damage discharge electrodes. Our unit detects the current spike from an arc and immediately reduces output power. If the arc persists beyond a set time—adjustable by the user—the unit trips completely. This prevents pitting and extends electrode life.

All protection events are logged with time stamps and stored in non-volatile memory. Operators can retrieve fault history through the communication interface.

Monitoring and Control

RS-485 with Modbus RTU is standard. Ethernet with Modbus TCP is available as an option. Through these interfaces, you can connect the unit to a plant DCS or SCADA system.

From a remote location, operators can read output voltage, output current, fault status, internal temperature, and power consumption. You can also adjust voltage and current setpoints, change control modes, and reset faults remotely. This reduces the need for on-site visits, especially for installations in confined spaces or high-risk areas.

For analog control, we provide 4–20 mA inputs for setpoint and outputs for status signals, as standard.

Physical Design

The high-frequency design significantly reduces size and weight. A 100 kW unit occupies about one-tenth the volume of an equivalent 50/60 Hz transformer. This makes retrofits practical when replacing older units in crowded electrical rooms. Weight is similarly reduced, so installation doesn't require heavy lifting equipment.

Cooling is forced air for models up to 50 kW, and water-cooled for higher power ratings or for installations where ambient temperatures exceed 40°C. Standard enclosure rating is IP20 for indoor use; IP54 is available for outdoor or dusty environments.

Applications

These power supplies are deployed in several industrial environmental applications:

Electrostatic precipitators for flue gas dust collection in power plants, cement kilns, steel sintering plants, and incinerators. The stable DC output improves collection efficiency and reduces stack emissions.

Plasma VOCs treatment systems for decomposing volatile organic compounds in exhaust streams from chemical plants, coating lines, printing facilities, and pharmaceutical manufacturing.

Industrial oil fume and mist treatment for machining operations, food processing, and textile stenter machines.

Odor control systems for wastewater treatment plants, composting facilities, and rendering operations, where plasma or corona discharge is used to break down H₂S, ammonia, and other odorous compounds.

Air purification units for commercial buildings, cleanrooms, and medical facilities.

Reliability and Testing

We've been manufacturing high-voltage power supplies since 2006. Our installed base exceeds 2,000 units across China, Southeast Asia, the Middle East, South America, and Europe. Many of these operate in cement and steel plants where ambient temperatures regularly exceed 45°C and dust loads are heavy.

Field data from these installations gives us a mean time between failures of just over 80,000 hours. That number is based on actual operating logs, not theoretical calculations.

Each unit undergoes a 48-hour burn-in test at full rated load before shipping. We also perform a high-voltage withstand test at 1.5 times rated output for one minute. Every protection function is verified individually during final test.

Critical components—IGBT modules, high-voltage transformers, capacitors, and control boards—are sourced from tier-one suppliers. We inspect every batch on arrival and maintain traceability records for all key parts.

Customization Options

We offer custom configurations for non-standard voltage, current, or mechanical requirements. Examples include units for specific plasma chemistries, for maritime scrubbers with salt-spray resistance, and for high-altitude installations requiring derating adjustments.

Our engineering team can assist with interface matching, control logic adaptation, and harmonic filtering. We also provide on-site commissioning support for larger projects, though most units are pre-configured to work out of the box with standard ESP or plasma systems.

Documentation and Support

Each unit ships with a complete manual covering installation, wiring, operation, troubleshooting, and maintenance. We provide technical support by email and phone, with response within 24 hours for standard inquiries. For urgent issues, we can arrange remote diagnostics via the communication interface.

Spare parts are held in stock for current models, and we maintain documentation for units shipped within the last ten years to support legacy equipment.