The application of class B insulation to auxiliary-type D-C motors in severe duty service

IN three papers^,1,2,3 recently presented before the AIEE the life characteristics of class A insulation were discussed along with the rating, duty cycles, temperature measurements, and application of class A insulated induction motors. It is believed that a paper covering the application of class B insulation to electric motors would be in order. This paper is intended to show the advantages of class B insulation for certain applications, especially in d-c motors for severe duty service. The d-c motors covered by this paper are for: 1. Steel-mill auxiliary drives (totally enclosed and forced ventilated): screwdown, manipulators, side guards, table, shear, pinch roll, cranes, etc.