Pre-Planned Maintenance

04.11.22

We recently carried out pre-planned maintenance of a Vacuum HV Switchboard. While carrying out secondary injection testing of the circuit breaker protection relays, it was discovered that one of them was faulty.

After discussing the issue with the customer, it was agreed that the affected transformer could be left isolated while a replacement relay was installed. Despite the relays no longer being in production, we swifty sourced a suitable replacement relay and arranged a return visit with the customer to carry out the works. Once a date had been agreed, we returned to site to remove and replace the faulty relay, ensuring that it was secondary injected to check that it operated correctly and within the given time. The affected transformer was then put back into service, safe in the knowledge that if there was an overcurrent or earth fault on that circuit, the associated protection relay would operate.

This scenario highlights the importance of carrying out planned preventative maintenance on private HV networks, as if these checks were not carried out, the closest relay to a future fault would not have operated. This would have resulted in a more widespread and costly power outage as the next relay upstream could be protecting multiple circuits and transformers.

If you would like to discuss your requirement with regards to PPM of your private HV network, please get in touch with one of our engineers on 01529 410999.

Many thanks to you and your team for the maintenance and the remedial repair on our HV switchgear. A job well done. It’s been a pleasure working with you and your team and look forward to working with you all again in the future.

Ryan Cooper (ISS On Site Supervisor)

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