2006 Muttrah Incident Report - authority for electricity regulation, oman

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elevant terms and conditions of their contract with MEDC were passed on to their supplier ABB Arab. On site safety the inquiry concludes that the use of a Limitation of Access for carrying out the work was not appropriate given that the VCB/trucks had never been tested in a Brush cubicle. However the design defects identified in this report would have manifested themselves in any case irrespective of the site safety precautions taken 1.2 Recommendations The inquiry makes a number of recommendations in respect of the circumstances surrounding this incident: Retrofitting Further retrofitting of switchgear should not be carried out unless: • It is carried out by the original equipment manufacturer (OEM); or • If carried out by someone other than the OEM it shall be subject to testing in the original cubicle and witnessed by a reputable switchgear test house. Contracts Licencees should ensure that: • When submitting offers, contractors/suppliers comply strictly with all the terms and conditions of the invitation to tender; • That all the terms and conditions of a contract (e.g. production of drawings, certificates etc ) are enforced; • That close liaison is maintained between the Contracts Department and the field staff responsible for the supervision of the execution of a contract. Site Safety Licencees should ensure that: • A safety risk assessment is carried out for all non-routine work on or adjacent to live equipment. This assessment should be carried out by an HSE specialist not involved in the proposed work. 6
2 SCOPE OF INVESTIGATION AND METHODOLOGY 2.1 Summary of the Incident At 1846 hrs on Tuesday 28 March 2006 on the distribution system of Muscat Electricity Distribution Company at Muttrah Old Stores Primary Substation a flashover occurred on the Busbar and Feeder spouts of the Al-Harthy/Local Transformer 11 KV Circuit Breaker. As a result of the incident two employees of ABB Egypt, sub-contractors to Al-Wadi Company were severely burnt and subsequently succumbed to their injuries in Khoula Hospital on Sunday 2 April 2006. 2.2 Scope of investigation As a result of the incident the Authority for Electricity Regulation, Oman (the ‘Authority’) set up a technical inquiry with the following Terms of Reference: To enquire into the technical circumstances surrounding the fatal accident that occurred at Old Muttrah Stores Primary Substation at 1846 hrs on Tuesday 28 March 2005. The inquiry shall specifically include the following: a) The sequence of events that led up to the incident; b) The safety precautions in place at the time of the incident; c) The sequence of events following the incident including the provision of first aid to the injured persons; d) The specification and scope of the contract for retrofitting of vacuum switchgear; e) The training given to all persons involved in the incident. 7
Page 1 and 2: REPORT INTO THE INCIDENT AT MUTTRAH
Page 3 and 4: GLOSSARY OF TERMS The terms defined
Page 5: 1 INTRODUCTION AND SUMMARY OF FINDI
Page 9 and 10: 2.3 Methodology In preparing its re
Page 11 and 12: outages on the distribution system
Page 13 and 14: FIGURE 2 Brush OCB Truck removed Mu
Page 15 and 16: contracts were subsequently awarded
Page 17 and 18: 5 SEQUENCE OF EVENTS The sequence i
Page 19 and 20: The protection relay indications fo
Page 21 and 22: BUSHING SHUTTER FIGURE 4 Reconstruc
Page 23 and 24: FIGURE 7 Truck - Cubicle Interface
Page 25 and 26: the shutter mechanism is mounted is
Page 27 and 28: 6.3 Cause of the Incident Based on
Page 29 and 30: shortcomings in the trucks supplied
Page 31 and 32: Subsequent to the incident it emerg
Page 33 and 34: • That the design defects identif
Page 35: 10 RECOMMENDATIONS The inquiry make

2006 Muttrah Incident Report - authority for electricity regulation, oman

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