Method for testing the phase imbalance of a three-phase cable due to termite attack

By forming signal loops at both ends of a three-phase cable, outputting step signals and calculating phase imbalance, the problem of inaccurate testing in existing technologies is solved, enabling accurate assessment of phase imbalance caused by termite infestation and ensuring stable operation of the power grid.

CN122282604APending Publication Date: 2026-06-26FOSHAN POWER SUPPLY BUREAU GUANGDONG POWER GRID
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
FOSHAN POWER SUPPLY BUREAU GUANGDONG POWER GRID
Filing Date
2025-12-15
Publication Date
2026-06-26

AI Technical Summary

Technical Problem

Existing technologies cannot accurately test the phase imbalance of three-phase cables after termite infestation, which can lead to local electric field distortion, accelerated insulation aging, and even phase-to-phase short circuits and breakdowns during operation, affecting the reliability of power grid supply and equipment maintenance costs.

Method used

By stripping the outer sheath at both ends of the cable, a loop is formed from the signal source to the cable sheath, to the ground, and to the oscilloscope. A step signal is output, the cable response signal is recorded, and the dispersion coefficient, average state coefficient, and LZ index are calculated. Combined with the LZ76 algorithm, the phase imbalance of the three-phase cable is calculated to determine the degree of termite infestation.

Benefits of technology

It enables precise testing of the unevenness of termite infestation between phases in three-phase cables, providing early warning of fault risks, extending cable lifespan, and ensuring the reliability of power grid supply.

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Abstract

This invention discloses a method for testing the phase-to-phase imbalance of a three-phase cable due to termite infestation, characterized by the following steps: forming a complete circuit of "signal source - cable sheath - ground - grounding electrode - oscilloscope"; turning on the excitation signal source and recording the time-domain data of the pulse signal response in both undamaged and damaged states; calculating the balance coefficients wA, wB, and wC of each phase of the cable; calculating the phase-to-phase imbalance Y of the three-phase cable due to termite infestation; and determining the phase-to-phase imbalance of the three-phase cable due to termite infestation.
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