At Sellindge Feeder station during a monthly thermographic and ultrasonic survey, a problem was found. At the load balancer, a 110 V DC supply MCB was found to have a terminal at a temperature of 84 C. This MCB provided the DC supply to the computer controlling the load balancer.
As a result, once the problem had been found, an outage was taken during engineering hours to further investigate the problem. During the outage, it was found that the terminal crimp was faulty - this was removed and a new crimp fitted. The MCB had not suffered any damage because of the early detection of the problem.
As a result of this early detection, not only did we prevent further damage but more significantly the load balancer computer did not suffer a loss of supply. If the supply had been lost, the load balancer would have stopped. This in turn would have caused a loss of supply to the CTRL power supply.
This loss of supply would have had the impact of stopping trains whilst the MV supplies were re-configured from an alternative feeder station. This would have also generated significant delay costs in the region of GBP 600 per minute per delayed train. So if twenty trains are delayed by five minutes, the cost is approximately GBP 60,000.
Many thanks to Nigel Dalton at EDF for this contribution.
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