Operation and Maintenance

Condition Monitoring of XLPE Cable Termination

Deterioration Diagnosis of XLPE Cable Termination by Dissolved Gas Analysis

Background Purpose

Gas sampling work at XLPE cable termination
Gas sampling work at XLPE cable termination


Very small signal generated from defective part in cable termination is to be detected.
Permanent installation of signal detecting device is necessary.

New Method

Gas in cable termination is sampled and analyzed. Deterioration condition is evaluated by typical dissolved gas generated due to deterioration.


  • Non-destructive deterioration diagnosis by gas sampling from specific connector attached on the termination.
  • Quantitative diagnosis assessment by analyzing the amount of typical dissolved gas.
  • Cost effective comparing with conventional method.


One of failures of XLPE cable system is caused by deterioration of cable terminations.
The failure is generally caused by intermittent partial discharges (PDs) between pre-formed insulation and XLPE insulation due to overvoltages based on switching surges or pre-formed insulation.
We focused on gasses generated by PDs and analyzed the amount of acetylene, and succeeded in quantitatively evaluation of its deterioration.

Gas production mechanism
Gas production mechanism
Judgement from gas analysis result
Judgement from gas analysis result


This deterioration diagnosis has been carried out on our facilities since 2010. We have replaced deteriorated XLPE cables that abnormalities are found on 6.7% of diagnosed terminals. We have realized appropriate preventive maintenance without any failure on XLPE cable terminals since the introduction of this diagnosis.

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