High voltage fault causes outage at Global Switch 2 data centre

What happened

On 10 September 2016, a high voltage fault in the cable end box of the output circuit breaker for one on-site diesel rotary uninterruptible power supply at the Global Switch 2 data centre in London interrupted power for 222 milliseconds. All customers lost access to services based in the facility, and the fault affected the supply feeding the Claranet suite. The Register reported that one customer was knocked offline for two days.

Claranet said power was cut just before 11.00am, hardware was powered up by 1.30pm, and 85 per cent of its customer services were restored by 5.10pm. Damaged components were replaced and cable terminations on the remaining DRUPS units were checked. This was the second outage at the site in three months. A June outage was thought to have been triggered by a lightning strike.

Contributing factors

A high voltage fault within the HV cable end box of the output circuit breaker for one DRUPS unit. Global Switch said one of four power stations experienced a 222 millisecond switching event, while the site infrastructure protected supplies.

Lessons learned

1. After a high voltage fault on one DRUPS unit, check cable terminations on the remaining units before normal operation resumes.
2. Plan controlled restoration after even a very short supply interruption, because customer services may take far longer to recover than the electrical event itself.
3. Keep affected customers informed while power and services are brought back in stages.

Source

theregister.com