DC high-voltage generators are key instruments for conducting preventive insulation tests on high-voltage electrical equipment in power systems, industrial and mining enterprises, and research institutions. They are mainly used for DC withstand voltage tests and leakage current detection on power cables, zinc oxide arresters, transformers, generators, and other equipment.
The current mainstream DC high-voltage generators generally adopt PWM high-frequency pulse width modulation technology and high-power IGBT devices, featuring small size, light weight, high output voltage stability, and low ripple coefficient.
I. Core Working Principle
The working process of modern DC high-voltage generators can be summarized as inversion – boosting – voltage doubling rectification, and is combined with closed-loop feedback to achieve stable output:
Inversion: 220V industrial frequency AC is rectified and then inverted into high-frequency AC of several thousand to tens of thousands of hertz through a PWM pulse width modulation circuit and IGBT devices.
Boosting and voltage doubling: The high-frequency voltage is boosted by a medium-frequency transformer and then converted into DC high voltage by a voltage doubling rectification circuit composed of high-voltage silicon stacks and capacitors.
Closed-loop feedback: Voltage large feedback technology is used to monitor the output voltage in real time and dynamically adjust the PWM signal to ensure stable output high voltage, with a ripple coefficient typically ≤1%.
II. Key Technical Indicators and Selection
When technicians select models, they focus on three core parameters: output voltage, output current, and control accuracy. Combined with common series parameters in the industry, different specifications correspond to different application scenarios:
60kV/2mA: Rated voltage 60kV, rated current 2mA, rated power 120W, suitable for cables and arresters of 35kV and below.
120kV/5mA: Rated voltage 120kV, rated current 5mA, rated power 600W, suitable for 110kV cables, arresters, and medium and small-sized transformers.
200-300kV/10mA: Rated voltage 200-300kV, rated current 10mA, rated power over 2000W, suitable for cables of 220kV and above, long cables, and large generators.
Selection Key Points
Voltage level: Determined based on the higher test voltage of the test subject, generally 2-2.5 times the rated voltage of the equipment.
Current capacity: For equipment with large capacitance such as cables and capacitors, the rated current needs to be matched carefully; the 2mA model is suitable for small current tests such as arresters, and the 5mA or 10mA models are often used for long cable tests.
Accuracy requirements: High-end equipment can achieve a voltage regulation accuracy of 0.5%, with a ripple coefficient ≤0.5%, meeting the accuracy requirements for microampere-level leakage current measurement.
III. Special Features and Safety
Modern DC high-voltage generators are suitable for various test scenarios and have multiple practical functions, effectively improving test efficiency and safety:
0.75UDC₁ₘₐ one-click test: Specifically designed for zinc oxide arrester tests, after measuring the reference voltage of the arrester, the instrument can automatically reduce the voltage to 75% to conduct leakage current measurement, without manual adjustment, simple operation, and reliable accuracy.
Multiple protection mechanisms: Standardly equipped with overvoltage protection, overcurrent protection, zero position protection, grounding protection, and an emergency stop button; some intelligent models also have functions such as inability to boost voltage when grounding is poor and protection for broken voltage measurement circuits.
Structural design: Mostly adopts a split structure, consisting of a control box and a voltage doubling cylinder. The voltage doubling cylinder uses new insulating materials, with strong portability; in outdoor and high-humidity environments, insulation performance and moisture-proof ability are important considerations.
IV. Main Application Areas
Power systems: Regular DC withstand voltage tests and leakage current detection are conducted on core equipment such as power cables, GIS, transformers, and switches to accurately identify insulation defects. Lightning protection test: Detect the DC reference voltage (U₁ₘₐ) of the zinc oxide arrester and the leakage current at 0.75 times the voltage to assess the performance of the equipment.
Research and production: Serve as the charging power supply for impulse voltage generators and impulse current generators, or be used for the withstand voltage test of high-voltage components in factories.
Post time: Apr-01-2026