XZH TEST Completes 35kV Cable Fault Location in Gazipur, Bangladesh with Surge Method

A field service team has successfully located a high-resistance flashover fault on a 35kV underground power cable in Gazipur, Bangladesh, using time-domain reflectometry (the low-voltage pulse method) together with the high-voltage surge (direct flashover) method. The fault was pinpointed at 1,629.8 m from the test end on a cable whose measured full length was 1,896.2 m.

Gazipur, Dhaka Division, Bangladesh — August 27, 2026

The cable under test was a 26/35kV three-core, 400 mm² XLPE power cable (YJV 3×400 26/35kV) serving a distribution circuit. A fault recording had shown a disturbance on phase B, prompting an on-site diagnostic campaign to determine the fault nature and distance before any excavation work began.

The testing followed a staged diagnostic procedure, beginning with insulation resistance measurement and moving to withstand voltage testing and pre-location once the fault nature was confirmed.

1. The B phase was first measured to ground with an electronic megohmmeter on the 5kV range. The measured B-phase-to-ground resistance was 2.5 GΩ at 5,005V, indicating that the insulation appeared normal at low voltage, so a withstand voltage test was still required.
2. A DC withstand voltage test was then performed using a 5/50 operating console and test transformer. When the B phase reached DC 40kV, a flashover breakdown discharge occurred at the fault point.
3. Based on this behavior, the fault was classified as a phase-B flashover high-resistance fault.

Two pre-location methods were applied: the low-voltage pulse method and the high-voltage direct flash (surge) method.

Using the low-voltage pulse method, the full length of the cable was measured at 1,896.2 m. The direct flash method was then applied; as the voltage rose to 40kV the fault point formed a flashover discharge, and the fault distance was determined to be 1,629.8 m from the test end.

• For extremely high flashover discharge faults, the direct flash method is the recommended sampling technique.
• Most cable faults occur at joints, particularly on joints that have been in service for more than five years.
• If the cable route is not clearly known, the route must be traced before accurate pinpointing is attempted.

This field case in Gazipur demonstrates a reliable, structured approach to diagnosing and pre-locating 35kV cable faults — combining insulation testing, withstand voltage testing and dual-method pre-location to deliver an accurate fault distance before excavation.