Safe Implementation of HV Vacuum Switches in Oil & Gas Installations

Over-voltage occurrences inducing heavy damages to HV motors and transformers have been experienced in the recent years. Such fault events have been thoroughly analyzed to identify the root causes, particularly because of the potential economic impact after a breakdown, where the insulation has not self-restored. Voltage surges impacting HV motors and transformers most of the time originate from switching surges rather than from environmental factors, particularly when vacuum switching equipment is applied due to their ability to produce repetitive, high amplitude steep fronted surges during closing as well as during opening operations. The intent of this paper is to use the lessons learnt from recent failures experienced in oil & gas plant installations in order to propose recommended engineering practices for the safe implementation of the vacuum switching equipment assigned to HV transformers and motors energization.