AC dielectric withstand and diagnostic testing for underground power cable insulation integrity.
A Very Low Frequency (VLF) high voltage test is an AC dielectric withstand and diagnostic test used to check the insulation integrity of medium-voltage and high-voltage underground power cables (such as XLPE, EPR, and PILC).
Purpose: Replaces harmful DC testing (which can cause space charge accumulation and damage modern polymer insulation) with a safe AC stress test.
Frequency: Operates at an alternating current frequency of 0.01 Hz to 0.1 Hz (typically 0.1 Hz), which requires significantly lower power and smaller equipment size compared to standard 50/60 Hz testing on capacitive cable loads.
Waveforms: Uses sinusoidal, square, or cosine-rectangular AC voltage waves.
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