Sep 2013
Electricity Transmission
Dinorwig Thermal Cycling and Cable Rating
Sep 2013
National Grid Electricity System Operator
National Grid TO Innovation Team
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Innovation Funding Incentive
Gas Distribution Networks
Over recent years the 400kV electricity connection for Dinorwig Power Station has suffered from poor reliability problems associated with abnormally high Dissolved Gas levels in the cable fluid. These levels have forced National Grid Electricity Transmission to switch out the Dinorwig-Pentir 1 circuit in 2012 resulting in a circuit outage to replace the ‘gassing’ stop joint accruing costs of circa £150k per day.

An identical issue occurred in 2011 on the Dinorwig-Pentir 2 circuit with identification of another ‘gassing’ stop joint.

These incidents have prompted an action to probe further into the likely root cause as well as further studies to understand the resultant effects (pertaining to stop joints) from an aspect of thermal cycling.

The project aims to undertake a detailed study on the thermal cycling effects on the Dinorwig cable circuits with particular emphasis to the stop joints. The live data captured on site will enable a model to be developed of the stop joint using Finite Element Analysis. The results of this analysis should yield better understanding on the expected performance of these stop joints under differing load patterns as well as shed light on any relevant amendments regarding assumptions made in the current cable ratings model.