Failure of cable end boxes/link boxes can result in dangerous conditions for the general public with some faults being explosive in nature. The faults can occur when a combustible gas (mains gas or from insulation overheating) accumulates inside the cable end box and an explosion can occur when an ignition source is provided. The degradation of the cable insulation, which is accelerated by water ingress, lowers the dielectric strength of the insulation. The insulation damage eventually leads to further degradation through overheating of the insulation, partial discharge, tracking and eventually to arcing which can provide an ignition source.
Objectives
The aim of this project is to investigate parameters to be monitored and trended in order to understand the mechanisms of failure for cable end boxes. Commercial inspection tools were examined to determine the most appropriate monitoring system. An investigation of mitigation strategies has been conducted to reduce the health and safety risk in case failure cannot be avoided.
Method
The key stages in the delivery of this project are as follows:
- Literature review to determine the key parameters to monitor
- Commercial review to identify the most appropriate monitoring system and sensors to deploy in the cable end box
- Lab based testing at the University of Strathclyde for initial testing of the monitoring system
- Field trials on the PNDC network to test the monitoring system in a controlled environment
Outcome
A monitoring system will be proposed to identify parameters to be trended in order to prevent cable end box failure. The most appropriate mitigation strategies will be proposed. The main business improvement from this project is an increment of Health and Safety and minimising risk of injury to general public.