High-voltage (HV) lightning impulse voltage generator test systems are indispensable for evaluating the dielectric strength and resilience of electrical equipment, such as power transformers, insulators, and switchgear. These systems simulate transient overvoltages caused by lightning strikes or switching events, ensuring compliance with international standards like IEC 60060-1. This article delves into the components, operational principles, and significance of these test systems in maintaining grid reliability and safety.

Components of a Lightning Impulse Test System

A typical lightning impulse test system consists of a Marx impulse generator (MIG), chopping circuits, measurement instruments, and control units. The MIG employs multiple capacitor stages charged in parallel and discharged in series to generate high-voltage impulses. Key elements include front and tail resistors, which shape the waveform, and a chopping device that truncates the impulse to simulate dielectric breakdown scenarios. The system must minimize parasitic inductance and capacitance to avoid oscillations and overshoot, which can distort results and lead to non-compliance with standards [citation:1][citation:4].

Standards and Waveform Requirements

According to IEC 60060-1, a standard lightning impulse voltage waveform is defined as 1.2/50 μs (front time/tail time). Tolerances allow a front time (T1) of 1.2 μs ±30% and a time to half-value (T2) of 50 μs ±20%. For ultra-high-voltage (UHV) equipment exceeding 800 kV, the front time tolerance extends to 100% (2.4 μs). Overshoot—a damped oscillation at the waveform peak—must not exceed 10% to prevent undue insulation stress. Testing involves both full lightning impulses (FW) and chopped impulses (CW), with the latter peaking higher and interrupting within 3–6 μs after the voltage peak [citation:1][citation:5][citation:9].

Applications in Power Equipment Testing

Lightning impulse tests are critical for assessing the insulation integrity of transformers and other HV apparatus. During tests, reduced-level impulses are applied first, followed by full-voltage FW and CW impulses. Discrepancies between reduced and full-voltage waveforms may indicate insulation failures. High-frequency modeling of transformers, such as multi-transmission line or lumped-parameter models, ensures accurate simulation of transient responses. These models account for phenomena like skin effects and core losses, which influence voltage distribution across windings [citation:1][citation:4].

Challenges and Best Practices

Achieving standardized waveforms requires careful configuration of MIG parameters, including stage count, resistor values, and load capacitance. Excessive circuit inductance from long leads can cause overshoot, while incorrect resistor settings lead to non-standard wave shapes. Computational tools and low-voltage recurrent surge generators help optimize parameters before actual testing. Adherence to standards like GB/T 16896.1-2024, which aligns with IEC requirements, ensures measurement accuracy and instrument reliability [citation:2][citation:4][citation:7].

Conclusion

HV lightning impulse voltage generator test systems play a vital role in safeguarding power infrastructure against transient overvoltages. By complying with evolving standards and addressing challenges like overshoot and circuit inductance, these systems enable accurate validation of equipment durability. As UHV technologies advance, continued refinement of testing methodologies will remain essential for global energy resilience.