Evaluation of deterioration in aged GCBs and study on equipment replacement criteria

This paper describes an investigation of grease degradation of aged GCBs. Risk of depletion on conducting contacts due to grease degradation in particular was identified in field data. In addition, it was found that grease oil evaporation and abrasion dust infiltration were proportional to ages and numbers of operations respectively. It was also found that grease degradation promoted abrasion in silver-plating on sliding contacts, reaching the abnormal abrasion domain for aged equipment, which increased equipment failure risk. Meanwhile, replacement criteria were organized with asset management based on risk evaluation.