7. CONCLUSIONS AND RECOMMENDATIONS
7.4 Reporting issues
In response to the two loss of supply incidents, NGT, NGC’s parent company, EDF Energy, Aquila and East Midlands Electricity, all produced their own investigation reports which were intended for both internal and external consumption.
With regard to the reports issued by the four companies involved in the incident the NGT report is by far the more detailed, and justifiably so since the supply failures were on NGC’s
system. However, there were issues associated with the incident that, whilst not the direct cause of the loss of supply, came to light during our investigation and which had not been reported on in NGC’s own report on the incident. In particular we refer to:
a) association of the Buchholz alarm (that started the sequence of events that eventually resulted in the loss of supply) with the Hurst SR3 reactor rather than SGT3 and the fact that NGC had been “managing” the oil leak for some time,
b) the ambiguity of the alarm message and the consequent misinterpretation by the
ENCC control engineer,
c) the “back energisation” of NGC’s system when Hurst SGT4 transformer was
energised after ENCC omitted to check the status of its 132 kV circuit breaker that controlled the interface with EDFE at Hurst.
NGC has stated its view that each of these points were not in themselves the cause of the supply failure . Furthermore NGC’s has stated that its report on the incident which was produced within two weeks of the incident occurring was produced for a wide, generally non- technical audience, and that it therefore had to tailor the material it presented in the report to the audience. NGC has made significant efforts internally to investigate the two incidents and design and implement programmes to action a range of remedial measures covering a number of topics. These are listed under material presented in subsection 7.5.
7.5
Remedial action taken by NGC since the incidents
NGC has indicated in correspondence with PB Power following the issue of our draft report that since the London and West Midlands incidents occurred in August and September 2003 it has implemented a range of improvements and initiatives to minimise the risk of similar supply failures in the future.
NGT stated in its Investigation Report on the London incident that it was committed to a number of actions, which are repeated below:
1) NGC will work closely with other network operators to identify any improvements in co-ordination to enhance the overall security of electricity supplies, particularly to city centres and transport systems
2) NGC will work closely with EDF Energy, the Mayor, London Underground,
Network Rail and other London emergency and public service agencies to establish improved and more responsive communications in the event of major loss of supply.
3) NGC is urgently surveying all installations as a further check on the integrity of the automatic protection equipment.
4) NGC will carry out a further comprehensive investigation examining all aspects of the management of the protection systems so as to eliminate, as far as
possible, the risk of incorrect installation or operation of automatic protection equipment.
5) NGC will work to review operational procedures, and control room systems, including alarm presentation, in close consultation with Ofgem, DTI and other associated parties, to ensure that there is the right balance between safety risks and supply security.
Appendix H of this Volume presents a copy of NGC’s table identifying detailed actions to be taken arising from the (NGC) Investigation Report recommendations. The table addresses each of the five commitments listed above. It breaks down the various areas of
improvements and initiatives into individual tasks. These would seem to cover a large scope of activities addressing key issues such as protection commissioning, security of supply, communications, alarm ambiguities, DNO interfaces, reliability of supply to key sites and risks of leaving plant in service.
NGC has stated that the responsibility for addressing each of the recommendations has been given to a senior manager within NGT, an arrangement put in place following the incidents. NGT say that having recognised that their reports on the two incidents were less detailed than their usual approach they included in the reports broad recommendations for further work then established workstreams to examine the two incidents. The workstreams are all said to be active at present and the personnel involved are individually responsible for implementing the lessons learnt in their respective areas.
This demonstrates NGC’s commitment to learning lessons from the two incidents. It is encouraging that all of the issues that have been identified in our investigation are being followed up by NGC .