It perfectly solves two major pain points: the traditional power frequency (50Hz) test equipment is bulky and heavy, making it impossible to move on site, and the DC withstand voltage test is prone to generate "space charge" in XLPE cables, leading to insulation damage.
Combined with the technical standards and application status in 2026, here is an in-depth analysis of this device:
1. Core principle and necessity
Why is ultra-low frequency (0.1Hz) needed?
Capacitive current is significantly reduced: the cable is equivalent to a large capacitor. According to the formula
When f is reduced from 50Hz to 0.1Hz, the required test current is only 1/500 of the power frequency. This means that the power supply capacity and transformer volume can be reduced by hundreds of times, allowing the equipment to be packed into a van or even a suitcase, easily entering tunnels and pipe galleries for on-site testing.
When f is reduced from 50Hz to 0.1Hz, the required test current is only 1/500 of the power frequency. This means that the power supply capacity and transformer volume can be reduced by hundreds of times, allowing the equipment to be packed into a van or even a suitcase, easily entering tunnels and pipe galleries for on-site testing.
Avoiding DC damage: In the past, DC withstand voltage test was commonly used for XLPE cables, but the DC electric field can accumulate space charge in the insulation layer, forming local high field strength after voltage removal, which accelerates cable aging and even causes breakdown after commissioning. The 0.1Hz AC voltage has both the distribution characteristics of an AC electric field (no space charge generation) and the portability of ultra-low frequency. It is currently the internationally recognized (IEEE 400.2, IEC 60502) preferred method for XLPE cable acceptance and preventive testing.
Waveform standards:
Cosine Rectangular: early mainstream, mature technology, but slightly higher harmonic content.
Sine Wave: the mainstream trend in 2026. The waveform is purer, closer to actual operating conditions, more accurate for insulation assessment, and meets the latest national standards.
2. Key technical parameters (2026 version)
When selecting, the following indicators need to be focused on:
Output frequency: standard is 0.1Hz, high-end models support 0.01Hz - 0.5Hz continuous adjustment (for testing cables of different lengths or generators).
Output voltage: common levels are 30kV, 40kV, 50kV, 60kV, 80kV.
The test voltage for 10kV cables is usually
Induced withstand voltage test device
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