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High-voltage rotating machines cover nominal voltages of 3.3-30 kV, with power outputs ranging from 0.1 MW to over 1000 MW. They are used as drives in the industry where high power is required and as generators in power plants. In all cases they must operate efficiently in harsh environments, therefore reliability and low-maintenance operation are key. In particular, power generators are viewed as long-term investments with an expected lifetime of up to 40 years. The design and manufacture of rotating machines must deal with these requirements, and the insulating system of a high-voltage rotating machine has a substantial influence on its lifetime. It is therefore important that it be carefully selected and applied.
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Brütsch et al. (2010) studied this question.