10kV Cable Fault Location in Istanbul, Turkey: HV Flashover Method Pinpoints Fault at 172m on 177m YJV Cable

ISTANBUL, Turkey — A 10 kV underground cable fault location project was recently completed in Istanbul, Turkey, by our cable fault detection team. By combining insulation resistance testing, the low-voltage pulse method and the high-voltage flashover method, engineers pinpointed a leakage-type low-resistance fault at 172 m along a 177 m YJV cable, providing the local utility operator with an accurate excavation reference and reducing outage time to a minimum.

Project Profile

The target line was a 10 kV medium-voltage distribution cable serving an industrial area in Istanbul. The operator reported a ground fault that tripped the feeder, and the cable was isolated for diagnosis. The key project information is summarized below:

Step 1: Insulation Resistance Testing

Using an insulation resistance tester on the 2500 V range, the team measured the resistance of each phase to ground: A-phase 0.03 MΩ (169 V), B-phase 0.04 MΩ (155 V) and C-phase 0.01 MΩ (146 V). The extremely low readings on all three phases indicated a leakage-type low-resistance fault rather than a high-resistance breakdown, and guided the selection of the most suitable fault location methods.

Step 2: Low-Voltage Pulse Method

The low-voltage pulse method was then applied to measure the cable and evaluate the fault condition. The instrument returned a cable length of 177 m for the C phase, with the other phases also measuring 177 m. The fact that the fault distance could be read directly by the low-voltage pulse method confirmed that the resistance at the fault point had already dropped to an extremely low level.

Step 3: High-Voltage Flashover Method

To verify the fault distance precisely, the team switched to the high-voltage flashover method. The test voltage was raised to 28 kV, and the fault point was measured at 172 m — just 5 m short of the far cable end. Waveform analysis showed a clear flashover at the fault location, giving the on-site crew an accurate and reliable digging point.

Key Takeaways

• The low-voltage pulse method successfully measured the fault distance, indicating that the resistance at the fault point was already extremely low.
• During pinpointing, technicians must proceed with great care: because the fault resistance is very low, the discharge sound at the fault point may be extremely faint.
• Accurate distance measurement (172 m on a 177 m cable) minimizes unnecessary excavation and speeds up power restoration.

This project once again demonstrates the efficiency of combining insulation resistance testing, low-voltage pulse ranging and high-voltage flashover verification for 10 kV cable fault location. With professional cable fault locators and experienced on-site engineers, our team helps utility and industrial customers in Turkey and beyond restore power quickly and reduce the economic losses caused by prolonged outages.