Patent ID: 8423301

Claim:
A lifetime assessment apparatus for an oil-filled electrical device including a winding having a conductor covered with insulating paper, a tank containing said winding, and an insulating oil filling said tank, said lifetime assessment apparatus comprising: a measurement unit configured to measure a residual concentration of a causative substance contained in said insulating oil and reacting with said conductor to generate an electrically conductive compound; a concentration estimate unit configured to estimate an initial concentration of said causative substance based on an operating time of said oil-filled electrical device and a measurement value of said residual concentration measured by said measurement unit; and a comparison unit configured to compare a reference value of said initial concentration with an estimate value of said initial concentration estimated by said concentration estimate unit, said reference value being defined as a value for determining whether a main determinant that determines a lifetime of said oil-filled electrical device is generation of said electrically conductive compound or degradation of said insulating paper; and an assessment unit configured to assess the lifetime of said oil-filled electrical device, based on a result of comparison between said estimate value and said reference value.