This Very Low Frequency (VLF) tester is a specialised tool for assessing the insulation integrity of high-voltage cables by applying a low-frequency AC voltage (typically 0.1 Hz to 0.02 Hz). It is used for commissioning, maintenance, and diagnostics reducing the power requirements weight for better portability compared to traditional 50/60 Hz testing. The tester applies an overvoltage to stress the insulation, which helps detect weaknesses that could lead to premature failure.