latest company case about Xi'an Xu&Hui Electromechanical Technology Co., Ltd. Certifications

Project Background

On May 3, 2026, a 10kV industrial power cable network in Santiago, Chile experienced a critical fault that disrupted operations between a motor control center and the main distribution room. The affected cable, installed on elevated cable trays throughout the facility, showed one phase with an alarmingly low insulation resistance reading of 0.7Ω to ground. Our testing team was dispatched immediately to perform a comprehensive fault detection and location procedure, with the goal of minimizing downtime and enabling precise excavation at the failure point.

Initial Insulation Assessment

The diagnostic process began with comprehensive insulation resistance measurements using a digital multimeter and a 5kV insulation resistance tester. Testing revealed a single anomalous phase—C-phase measured only 0.7Ω to ground—while the remaining phases displayed normal insulation characteristics. This low-resistance reading strongly indicated a solid conductive path between the C-phase conductor and the cable armor/ground, consistent with mechanical penetration damage rather than gradual insulation degradation.

Fault Detection and Precision Location

Phase 1 — Low Voltage Pulse Reflectometry

The 502 cable fault locator was deployed in low-voltage pulse mode to compare the faulted phase waveform against a known-good reference phase. The reflected pulse from the C-phase indicated a fault distance of 185 meters from the test terminal, while the healthy reference phase produced a full-length measurement of 298 meters.

Phase 2 — High-Voltage Flashover Verification

To eliminate ambiguity and validate the pulse method result, a high-voltage flashover test was conducted using a 5-50kV test transformer with a 40-6 capacitor discharge unit. The arc reflection waveform produced a consistent fault distance of 186 meters—within 1 meter of the low-voltage pulse estimate—confirming the location with high confidence.

Root Cause Analysis

Excavation at the identified location revealed the precise failure mechanism. During original installation, a self-tapping screw had been driven through the side of the cable tray into the C-phase conductor to secure the top cover plate in position. The screw did not cause an immediate short circuit—the cable continued to operate normally for an extended period—but over time, the compromised insulation at the penetration point gradually deteriorated under electrical stress and environmental factors until complete dielectric breakdown occurred.

• Initial condition: Screw tip partially penetrating cable insulation without immediate conductor contact
• Progression mechanism: Progressive moisture ingress and partial discharge at the micro-defect site
• Final failure: Full insulation breakdown from combined mechanical damage and aging degradation
• Root cause category: Third-party damage (installation error) + delayed dielectric aging

Key Success Factors

• Dual-method verification: Using both low-voltage pulse reflectometry and high-voltage flashover methods eliminated false positives and provided a definitive location within 4m of the actual fault point
• Rapid diagnosis: The entire process—from initial insulation assessment through precision location—was completed without trial-and-error excavation
• Known cable route advantage: Pre-existing knowledge of the cable tray path enabled immediate on-site verification without requiring a separate route-tracing operation
• Multi-instrument workflow: The combination of a 5kV insulation tester, 502 fault locator, and HV flashover equipment provided end-to-end fault characterization in a single deployment