There are two failure modes for switchgear: breaker related failure and bus related failure. Breaker related failure is generally due to loss of lubrication, lack of preventative maintenance, and deterioration due to age. Symptoms of breaker failure include slowed breaker interrupting times, failure to operate, thermal deterioration of rear disconnects, and damage to protected equipment due to excessive through fault exposure. Bus related failure happens due to exposure to moisture, dust or other contaminants. Partial discharge (PD) is a leading indication of insulation breakdown occurring on the operating bus. Typically, partial discharge most commonly occurs in systems greater than 2000 volts and if left unaddressed can result in a complete breakdown of insulation systems. Due to this breakdown of insulation, there is often a conductive path created from either phase-to-phase or phase-to-ground allowing an arcing event to occur which often results in system failure. Symptoms of PD could include corona buildup, tracking on the bus/insulation or flashover events.