Introduction to DC High-Voltage Generators

DC High-Voltage Generators are specialized instruments designed for conducting direct current withstand voltage tests and leakage current tests on various electrical equipment. These devices find extensive applications in power departments, industrial plants, railways, chemical facilities, and power plants for insulation strength testing of equipment such as zinc oxide arresters, power cables, transformers, and generators :cite[1].

Technical Principles and Operation

Modern DC high-voltage generators employ PWM high-frequency pulse width modulation technology and high-frequency voltage multiplying circuits. They incorporate voltage feedback systems to enhance output stability, utilizing high-power IGBT devices and imported components for improved reliability :cite[1]. The measurement accuracy of these devices typically reaches ±1% for both voltage and current measurements, with ripple coefficients of ≤1.0% and voltage stability that remains within ≤0.5% even with power supply voltage fluctuations of ±10% :cite[1].

Key Applications in Industry

DC high-voltage generators serve critical functions across multiple industries:

• DC withstand voltage testing of power cables

• Measurement of conduction current for metal oxide arresters

• Insulation strength testing for transformers, generators, and switches

• Extended applications in electron microscopy and electrostatic painting :cite[1]

Technological Features and Innovations

Contemporary DC high-voltage generators incorporate several advanced technological features. Intelligent units now include LCD displays for real-time parameter monitoring, RS232 interfaces for data transmission, and fully automated zinc oxide arrester testing modes :cite[1]. Some models feature modular segmented structures that adapt to different voltage requirements, enabling their use at both higher and lower voltage levels while maintaining measurement accuracy :cite[7].

Series DC high-voltage generators utilize different stages of voltage multiplier circuits connected in series, capable of achieving outputs up to 600kV with leakage current measurement up to 800μA :cite[4]. These systems can regulate voltage rise rates between 0.5-9.9kV/s and maintain voltage regulation precision not less than 1% :cite[4].

Safety Requirements and Operational Considerations

Operation of DC high-voltage generators must be performed exclusively by professionals with "high-voltage testing certification" :cite[1]. Strict adherence to safety protocols is essential, including implementing two distinct disconnection points in the working power supply before it enters the tester, as specified in the "Power Safety Regulations" :cite[1]. Special discharge resistor rods must be used when discharging large capacitive test objects, with operators gradually approaching the test object with the discharge rod until direct grounding discharge can be safely performed :cite[1].

Recent Technological Developments

Recent research has focused on improving the efficiency and compactness of DC high-voltage generators. Studies on full-bridge converters with LLC resonant circuits have demonstrated conversion efficiencies reaching 93.9% at full load conditions under 10kV output voltage and 2.5kW maximum output power :cite[3]. This technology enables zero-voltage switching (ZVS) at turn-on transition in the primary side of the transformer and zero-current switching (ZCS) at turn-off transition in the secondary side diodes, significantly increasing conversion efficiency :cite[3].

For ultra-high voltage applications, development of five-stage DC-1MV ultrahigh voltage generators for applications such as ITER have been successfully implemented, featuring series-connected generators that output -1 MV collectively and capable of continuous operation for one hour :cite[6].

Maintenance and Storage Guidelines

Proper maintenance of DC high-voltage generators ensures long-term reliability and accuracy. Electronic instruments should be powered on for at least 10 minutes monthly when not in use for extended periods. Equipment used in field environments requires regular cleaning, and storage warehouses must maintain dry conditions with adequate ventilation. Regular inspection of dust-proof installations is crucial, with prompt replacement or repair of any damaged or loosely connected components to prevent dust intrusion that could damage the equipment :cite[1].