What Is an Impulse Voltage Generator? Why Must High-Voltage Equipment Undergo Lightning Impulse Tests?

In the type testing and factory inspection of high-voltage electrical equipment, there is a test that appears "violent"—a high-voltage pulse lasting tens of microseconds is used to "strike" the device under test, observing whether the insulation can withstand it. This is the lightning impulse voltage test, and the equipment that generates this high-voltage pulse is the impulse voltage generator.

What problems does the lightning impulse test address

During actual operation, power equipment must not only withstand normal power frequency voltage but also endure lightning overvoltage and switching overvoltage. The peak voltage generated by lightning strikes can reach several tens of times the system's rated voltage, yet its duration is only on the order of microseconds.

The mechanism of insulation damage caused by such ultra-short high-voltage pulses is entirely different from that of power-frequency voltage—insulation breakdown does not require substantial energy; merely achieving a sufficiently high field strength within an extremely brief period can lead to breakdown in air gaps, transformer oil-paper insulation, or solid insulation materials. Without conducting impulse tests before equipment commissioning, it is impossible to verify whether it can withstand lightning surges during actual operation.

Positioning of HZCJ-400kV

The HZCJ-400kV/20kJ impulse voltage generator has a nominal voltage of 400kV and a nominal energy of 20kJ. It employs a four-stage Marx circuit structure and is suitable for full-wave standard lightning impulse voltage tests on air gaps, reactor switches, insulator strings, bushings, power transformers, and current/voltage transformers up to 35kV.

The waveform generated during the test is a standard lightning impulse full wave: 1.2/50µs (wavefront time 1.2 microseconds, wavetail time 50 microseconds), complying with national standards such as GB/T 311.1 and GB/T 16927.1. The voltage utilization factor exceeds 85% (over 90% at no load 300pF), ensuring sufficient peak voltage output under actual test conditions.

This set of equipment is designed to complement the type test laboratories of high-voltage research institutes, university laboratories, switchgear manufacturing plants, and transformer factories, serving as an irreplaceable professional tool for evaluating high-voltage insulation performance.