Evaluation of traction motor field coil insulation systems

These preliminary results indicate wide differences in thermal endurance between the insulation systems evaluated. These facts must be considered in selecting insulation systems for railway operation if continuity of service and low maintenance costs are to be maintained. Tests are continuing and will provide additional information about the performance of traction motor field coil insulating systems. While field service is the final proof of the reliability of insulation, this functional test procedure will be invaluable in evaluating present and new field coil insulation systems. Since it is unfair to expect the railroad companies to accept new insulation systems without functional data to substantiate the choice of materials, to supply these data becomes the duty of insulating material suppliers and coil and motor manufacturers.