Insulation Resistance Testing Method:
Apply a DC voltage (typically 500V or 1000V) to the cable and measure its insulation resistance. If the insulation resistance is below the standard value (e.g., 0.5MΩ), it indicates a risk of leakage. This method is suitable for initial screening of low-voltage cables but cannot pinpoint the leakage point.
Leakage Current Detection Method:
Use a clamp meter or dedicated leakage current detector to clamp the cable sheath or grounding wire and measure the leakage current. If the current exceeds a safe threshold (e.g., 30mA), further investigation is required. This method is suitable for dynamic monitoring but requires attention to environmental interference (e.g., electromagnetic fields).
Partial Discharge Detection Method:
Use a high-frequency sensor to capture partial discharge signals in the cable insulation layer to locate the leakage point. This method is highly accurate but the equipment cost is high, making it suitable for in-depth inspection of high-voltage cables or critical equipment.
Infrared Thermal Imaging Detection Method:
Use an infrared thermal imager to scan the cable surface and locate the leakage point through temperature anomalies. This method does not require power outage and is suitable for live detection, but it needs to be combined with other methods to confirm the nature of the leakage.
