Class H insulation system for railway traction motor

To raise power per unit weight and improve reliability of DC motors for rolling-stock, we have developed a new insulation system with high thermal endurance by adopting a solventless thermosetting resin for coil impregnation which consists of polyfunctional epoxides and heterocyclic compounds. Evaluation tests have revealed that the insulation system has excellent thermal endurance classified into class C and high reliability against the cyclic thermal stress. The newly developed insulation system can be applied to the class H insulation system for traction motors.