From rough measurement to precise location: Xi'an Xuzhihui Technology cracks the "latent" fault in a 7800-meter cable.

PART.1

Site Overview

PART.2

Testing process

• Determine the nature of the fault

After the withstand voltage test failed, the insulation resistance of A-ground, B-ground, C-ground, A-B, B-C, and A-C was measured using the 5kV range of the XHMR-5000V insulation resistance tester. It was found that the resistance of B-ground was 0.5MΩ (around 186V), while the others were all above GΩ; this indicates a high-resistance leakage fault.

• Test cable length

Using the low-voltage pulse method of the XHGG502 Cable Fault Locator. The total length of the cable was accurately measured to be 7799.4 meters (which matches the marked length of 7800 meters), confirming that the basic information of the cable itself is correct.

• "Double insurance" preliminary test, narrowing down the scope

High Voltage Surge Generator are output using an XHYB-5/50 test transformer and an XHCC-6/40 pulse energy storage capacitor. The XHGG502 Cable Fault Locator uses High Voltage Surge Generator to capture the discharge waveform at the fault point, and the rough fault distance is measured to be 2509.1 meters.

The bridge method for digital burn-out of the bridge: As an important supplementary method for verification, the rough measurement of the fault distance is approximately 2516.93 meters.

Key findings: The results from the two independent methods (2509.1 meters vs 2516.93 meters) are highly consistent. Due to the complex and winding path, the fault range can be reliably locked within the range of approximately 2300-2600 meters! This greatly narrows down the range for precise location.

• The path "clears the fog"

The cable route on site was unclear, and the farmland environment was complex. A detailed route review was conducted using an XHGX507C Cable Fault Pinpoint, clearly outlining the actual direction and depth of the underground cables, clearing obstacles for precise location determination.

• Precise targeting, decisive decision

Within a roughly measured range of 2300-2600 meters, along the complex path determined by the XHGX507C Cable Fault Pinpoint, a pulsed high voltage of 36kV was applied to fully discharge the fault point. Technicians, holding an XHDD503E cable fault locator, carefully listened to and analyzed the discharge signal directly above the path. Finally, at approximately 2500 meters from the test end, a clear and stable discharge sound was successfully detected at the fault point! Precise location and excavation confirmed the fault as a water ingress fault at a joint.

PART.3

Fault Testing Summary and Sharing

Precise and Reliable: Utilizing a combination of high-voltage flashover and bridge methods for dual verification of coarse testing, along with advanced pipeline positioning and precise pinpointing techniques, ensures accurate results. Professional Handling of Complex Cases: Specifically designed for high-resistance leakage faults such as "water ingress at joints." Water ingress at joints results in irregular high-voltage pulse discharges, making it difficult to detect high-voltage flashover waveforms at the fault point. Constant monitoring of these waveforms is crucial. In such cases, the bridge method is a key tool for verifying and supplementing coarse test results. Xi'an Xuzhihui Electromechanical Technology Co., Ltd. is a professional manufacturer of power cable fault detection equipment with 13 years of experience. We have an experienced technical team and provide efficient and accurate service. When your power cables encounter unexplained tripping, insulation abnormalities, or difficult-to-locate faults, please contact us immediately.