Application of the Equalized Ageing Process Method on Thermal Endurance Testing of Polyhydantoin Film

Thermal endurance test results on polyhydantoin film are presented, performed both in the conventional atmospheric conditions and in the conditions fulfilling the requirements for the equalized ageing process. The basic principle of the Equalized Ageing Process method (EAP) for thermal endurance testing of solid electrical insulating materials is to make the ageing process at the test temperature equal to that at the service temperature, by changing the test atmosphere appropriately. In an equalized ageing process all the chemical ageing reactions are accelerated equally. Test results in the EAP conditions are in very good agreement with the EAP theory, showing the same acceleration factor for chemical ageing reactions and for deterioration of physical properties. In the tests performed in the conventional atmosphere there was no common acceleration factor to be found for the chemical reactions and for deterioration rates of the physical properties. Consequently only those thermal endurance test results obtained using the EAP method can be a basis for calculating the useful life of the material at the service temperature.