The Rail Accident Investigation Branch (RAIB) today released its report into the failure of an overhead line at St Pancras International on 23 September 2009.
A full copy of the report is available here:
Summary
At approximately 18:35 hrs on 23 September 2009, the overhead wire supplying electric power to trains parted and fell onto the platform where passengers were leaving a Eurostar train which had just arrived at platform 9 at St Pancras. The supply system circuit breaker opened automatically to de-energise the wire, but the electrical controller made two attempts to re-energise the wire manually before an emergency isolation was applied. No one was hurt, although there was potential for injury to people on the platform from the movement and intermittent energisation of the damaged wire.
The RAIB investigation identified that the incident occurred because there was an abnormally high electric current flowing from the wire to the train. This was caused by:
- a flashover at the lightning arrester on the train, because the electrodes of the lighting arrester were too close together, and a high transient voltage had been induced by the closure of a circuit breaker;
- the incorrect connection of cables in the protection equipment which monitored the flow of current to the overhead wire, allowing the excessive current to flow for longer than the specified time;
- the absence of testing during the commissioning of the protection equipment, so that the incorrect connection of cables was not detected; and
- the electrical controller not following instructions before attempting to reclose the supply system circuit breaker.
The following actions have already been taken relating to issues raised in the report:
- EDF Energy has corrected the wiring errors in the protection equipment and examined installations on the CTRL similar to those at St Pancras and has not found any similar defects;
- Eurostar has undertaken a special examination of lightning arresters on all the trains in its fleet.
Recommendations
As a consequence of this incident, the RAIB has made a number of recommendations directed at the supplier of the electrical protection equipment (ABB Power), Eurostar and Network Rail. The RAIB has recommended that:
- Eurostar should review the design and maintenance of the lighting arrester;
- ABB Power should review its quality management processes in relation to the installation and testing of railway equipment;
- Network Rail should examine ways of controlling the risk from damaged overhead wires of the type in use at St Pancras; and
- Network Rail should review, and if appropriate amend, the performance specifications for overhead line and its protection equipment; Network Rail (CTRL) should review operating and training procedures used in the control room.
Notes to editors
1. The sole purpose of RAIB investigations is to prevent future accidents and incidents and improve railway safety. The RAIB does not establish blame, liability or carry out prosecutions.
2. For media enquiries, please call 020 7944 3248.
Newsdate: 5 August 2010
