1.1 This standard describes how the concentration of dissolved or free gases may be interpreted to diagnose the condition of a transformer in service and suggest future action.
1.2 The methods of evaluation covered are for power transformers wound with copper conductors, insulated with cellulosic paper or pressboard-based solid insulation and filled with hydrocarbon mineral oil, in service on power networks.
1.3 These methods may also be applied in principle to instrument transformers, oil filled cables, switchgears, etc, but because of insufficient experience, it is not possible to formulate suitable evaluation and limits.