Some of the cases of lost power reported to the PSA in 2010 were total blackouts, which involved both main and emergency supplies dropping out.
Losing the main electricity supply is not a serious threat to safety in itself, according to PSA principal engineer Eivind Sande.
“The systems are designed to fail-safe if the power is cut off ,” he notes. “But any unplanned irregularity in the production process increases risk, so such events must be avoided.
“An extensive power failure usually halts production as well, so it causes a financial threat as well as enhancing risk.
“In addition, loss of emergency power in an incident reduces opportunities for pursuing important response functions in a sufficiently robust manner - and must not happen.”
It can take time to get power generation and all the other systems up and running again. In one case last year, the installation was without power for almost two days.
Secure electricity provision is essential for a facility to function, whether transmitted by cable from land or generated on-site. The main power supply is needed for the many work processes on board as well as for lighting, heating, cooking, ventilation and sanitation.
If it fails, emergency generation will also be required to keep key systems going – such as emergency lighting, communication and safety systems. That applies not least during an evacuation.
A power failure on an installation can make life difficult for the crew, Mr Sande points out – particularly by boosting the risk of injury when the necessary lighting for work and movement is lost.
“If the incident lasts for a long time, heat will also be lost in workspaces and accommodation, indoor air quality will deteriorate and non-functioning toilets will pose problems.
“In such conditions, it can be necessary to reduce staffing on the installation to a minimum.”
The PSA intends to strengthen its supervision by implementing measures which persuade those responsible to deal with the challenges of safeguarding power supplies on installations, particularly with regard to emergency generation.