Assessment of machine and transformer insulation

Complex insulation assemblies such as transformers and rotating machines, apart from having to meet specified outputs, are required to operate virtually continuously for long periods of time. Many customers seek to operate their machines well beyond their design life through maintenance and refurbishment. An important factor in determining life is the insulation system, though this does not necessarily limit life. The author describes acceptance tests and in-service tests for the assessment of insulation quality in machines and transformers