There has been growing awareness of the risks posed by arc flash, particularly in the oil and gas sector, in response to new guidelines and standards developed by various international trade and safety bodies including the IEEE (Institute of Electrical and Electronic Engineers), the US Occupational Safety and Health Administration (OSHA) and Lloyds Register.
On the other hand, the impact of an arc flash incident in the sector can be significant, potentially causing injury and major damage to switchgear, with a knock-on effect on valuable process continuity.
The most practical method of reducing the impact is by reducing arcing time. Energy released during arcing is directly proportional to time. Even a few milliseconds less may shift hazard levels and PPE requirements to lower categories. Arcing that lasts 40 ms or less typically causes no personal injury or switchgear damage, whereas if left for 500 ms or more, an arc has the potential to result in serious personal injury and major damage to switchgear.
Offshore operators are now required to carry out studies to identify risk from arc flash and put protective measures in place. One approach is to supply and renew specialist PPE on an annual basis but operators could instead install ABB’s REA 10 system, which eliminates risk by reducing tripping times.
The REA system’s long unclad fibre optic sensor delivers ultra-fast detection by absorbing the light from a flash anywhere along its entire length and signalling for the circuit to break within only 2.5 ms. In normal operation, both intense light and over-current must both be present for tripping to occur.
Ian Hodkinson, Head of ABB’s Distribution Automation business in the UK said: “Winning type approval from DNV is a major endorsement for ABB’s REA Arc Flash Detection System. A typical substation might only experience a single incidence of arc flash in its lifetime but the impact is significant in terms of risk to life and limb, serious damage to electrical hardware and lost production time.”
REA protects the main distribution substation at Total’s Lindsey Oil Refinery
Boosting safety at South Humber Bank
Centrica Energy has improved its HSE (Health, Safety and Environment) performance at its South Humber Bank power station by retrofitting REA 10 arc flash protection systems to the site’s medium-voltage power distribution network.
The combined cycle gas turbine plant in north-east Lincolnshire has an output of almost 1.3 MW. By retrofitting the site’s existing ABB medium-voltage switchgear with REA 10 arc flash protection relays, Centrica has minimised the risk of arc flash incident from the 11 kV distribution network.