A transformer (26) is monitored by a dissolved gas monitoring device (28). A method (36) in the form of executable code instructs a processor (34) to estimate a remaining life (124) of the transformer. The method includes receiving (126), from the monitoring device (28) data elements (60) representing a current value (134) of dissolved gases (72) in the transformer (26) that correlate with degradation of insulating material in the transformer. Adjustment values (142, 144) are determined for the gases (72) in response to isolated events (160, 162) occurring at the transformer. The current value (134) and the adjustment values (142, 144) are combined to obtain a total value (114), and a degree of polymerization value (116) is estimated using the total value (114). The value (116) is converted into a measure of remaining life (124) of the transformer, and the measure of remaining life (124) is presented to a user (58).
