Testing device and method for testing a high or medium-voltage cable

A testing device for testing a high or medium voltage cable using a very low frequency (VLF) testing method, comprising:

• a circuit arrangement with
• a test voltage generator that comprises a low voltage side earthing input and a high voltage side output and is configured to provide a variable test voltage at the high-voltage-side output,
• a power connection for connecting the test voltage generator to a supply voltage source,
• a test specimen connection for connecting the high voltage side output to a conductor of the high or medium voltage cable,
• a protective earth connection for connecting to a protective earth,
• a connecting conductor that electrically connects the low-voltage-sidelow voltage side earthing input to the protective earth connection, so that the connecting conductor represents a current collection point through which a measuring current flows during the test of the high or medium voltage cable, which current is formed between the low voltage side earthing input and a shield of the high or medium voltage cable, which shield is also connected to the protective earth,
• a low frequency signal pick up at the current collection point, at which a low frequency diagnostic signal is generated based on the measuring current, and
• a high frequency signal pick up at the current collection point, at which a high frequency pre location signal for a measurement of a transient high frequency oscillation is generated based on the measuring current, and
• an evaluation electronics that
• is connected to the low frequency signal pick up for receiving the low frequency diagnostic signal and is configured for a VLF phase rotation measurement, and
• is connected to the high frequency signal pick up for recording the high frequency pre location signal and is configured for defect distance evaluation.