Safety aspects of HV machines in the offshore industry

During the period 1985 to 1991 a number of explosion incidents occurred, primarily offshore, involving high voltage certified Ex´e´ and Ex´N´ induction motors. Flammable gas had entered the machine enclosure and ignition had taken place resulting in varying levels of explosion damage to the equipment. At the time of each incident there was no evidence suggesting the presence of any explosive gas/air mixture external to the motors at the time of the explosion and equipment maintenance records were satisfactory. Other, possibly related incidents, have also occurred during that period which did not develop into incidents involving explosions. The authors discuss the roles and responsibilities of the HSE regarding such incidents and summarise the HV motor incidents. The research by ERA Technology and the Rotating Electrical Machines Association is discussed. The regulatory authority safety notices and alerts issued following the incidents, and a survey of offshore installations covering Ex´e´ and Ex´N´ electric motors >1 kV are outlined. The UK offshore oil and gas industry legislative framework and the European standard EN 50269 are also discussed