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10kV Cable Fault Location Case in Almaty, Kazakhstan: High-Resistance Ground Fault Pinpointed at 371.5m

2026-09-07

10 kV Cable Fault Location Field Test - Almaty, Kazakhstan

Leakage-type High-resistance Ground Fault Pinpointed at 371.5 m | August 17, 2026

On August 17, 2026, XZH TEST engineers carried out an on-site power cable fault location task in Almaty, Kazakhstan. The subject cable was a YJV 3*35 8.7/10 kV three-core power cable with a total route length of approximately 750 m, laid directly buried with both ends connected into switchgear cabinets. A ground fault had occurred on one phase, interrupting normal power transmission and requiring rapid and accurate fault location.

1. Fault Characterization

Insulation condition was first checked with an electronic insulation resistance tester at the 2.5 kV range. The measurement showed that the insulation resistance of one phase to ground was only about 0.1 MΩ (effectively zero), while the resistance between the other phases and between the remaining phases and ground all remained above GΩ. Based on these readings, the fault was classified as a leakage-type high-resistance fault - a typical fault form that cannot be located by simple continuity checks and requires dedicated cable fault locating instruments.

2. Testing Procedure and Results

The low-voltage pulse method was applied first to identify the full cable length from the reflected waveform, which was measured as 739.2 m and matched the site records. Afterwards, the high-voltage flashover (surge) method was adopted to test the faulty phase. When the test voltage was raised to 10 kV, the fault point broke down and a clear flashover waveform was captured. The fault distance calculated from the waveform was 371.5 m from the test end, which is close to half of the total cable length.

The complete field test report is shown below:

Project	10 kV Cable Fault Location Field Test - Almaty, Kazakhstan
Test Team	Lead Engineer: Qiao Yifan Team Member: Yang Xintao
Test Date	August 17, 2026
Cable Type	YJV 3*35 8.7/10 kV
Site Conditions	The cable is directly buried. Both the sending end and the receiving end are terminated in switchgear cabinets.
Fault Nature	Insulation resistance of phase-to-ground and phase-to-phase was measured with an electronic megger at the 2.5 kV range. The resistance of one phase to ground was about 0.1 MΩ (near zero), while the other phases and phase-to-ground readings were above GΩ. The fault was preliminarily identified as a leakage-type high-resistance fault.
Cable Length	Approximately 750 m for the full test route.
Rough Distance Measurement	Low-voltage pulse method for the full-length waveform; low-voltage pulse method combined with high-voltage flashover method.
Waveform Analysis	The low-voltage pulse waveform measured the full cable length as 739.2 m. The flashover method was then applied; when the voltage was raised to 10 kV, the fault point broke down, and the fault distance calculated from the captured waveform was 371.5 m.
Summary	Fault testing must follow the standard test procedure; skipping any step may extend the locating time. When capturing high-voltage waveforms, the applied voltage should not be set too high, as excessively high voltage may cause multi-point discharge and make the flashover waveform irregular.

3. Key Takeaways

Fault location must follow the complete standard test procedure; omitting any step (for example, skipping full-length measurement before flashover testing) may significantly increase the locating time.

When capturing high-voltage flashover waveforms, the applied voltage should be controlled at a moderate level. An excessively high voltage may trigger multi-point discharge, making the flashover waveform irregular and difficult to interpret.