A case study involving the resolution of certain engineering and logistical problems encountered in upgrading existing obsolete 15 kV 750 MVA air magnetic switchgear to meet a 1000 MVA application at an integrated pulp and paper mill is presented. The existing 15 kV switchgear is essential to the mill's operation, and could not be shut down for construction purposes. The solution was to utilize a retrofitting technique. The technique involves removing the existing circuit breaker element from its cubicle and stripping off everything associated with the old breaker. The stripped breaker element frame is refitted with state-of-the-art vacuum interrupters. The retrofitted assembly is reinserted into the existing cubicle and placed into service. The mill site application requirements, the selection of a qualified retrofitter, the retrofitting procedure, the benefits of retrofitting and the testing and installation experience are described.
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