Motor Dielectric Insulation & Surge Protection

Please advise how to select/specify adequate dielectric insulation on medium voltage motors.
a- Could be any economic advantage to specifify lower insulation level adding surge protection (capacitor & arrester)for similar level of reliability?.
b- There is any experience of motor dielectric failure caused by switching surge with vacuum devices?.

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Please advise how to select/specify adequate dielectric insulation on medium voltage motors.
a- Could be any economic advantage to specifify lower insulation level adding surge protection (capacitor & arrester)for similar level of reliability?
///Yes. In terms of protecting the motor insulation from the voltage surges, spikes, etc. that are most detrimental to any insulation, in general.\\b- There is any experience of motor dielectric failure caused by switching surge with vacuum devices?
///Yes. There might be some closely related content in IEEE and IEE publications:
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