Environmental Qualification of F insulation class Form wound Motor Winding using Vacuum Pressure Impregnation

Usually, the large motors important to safety for NPPs located outside containment in PWRs. Though they work important part to safety function, they don't have to environmentally qualified because they are located in mild conditions. But the large motors in PHWRs, important to safety, must be environmentally qualified according to IEEE Standard 323 due to their location, inside containment. Type test is recommended qualifying method for electric equipment, carried out type testing to qualify F insulation class form wound motors for totally enclosed type F insulation class form wound motors and open type F insulation class form wound motors both. The type testing to qualify F insulation class form wound motors for totally enclosed type and open type were passed for more than 40 years in PHWRs environment parameters. To use the type testing result for identical or similar motors, the motor windings must be replaced with the tested type winding in case of open type F insulation class form wound motors because they are not the same form wound windings even if they are same F insulation class. For motors, winding is the most important component and the price of this component is more than half of total cost. It is not reasonable to rewind motor to qualify open type F insulation class form wound motors instead of buying new one. To solve this problem, I tried to qualify open type F insulation class form wound motors not by rewinding but by re-VPI(Vacuum Pressure Impregnation) for used motors. In this paper, I'd like to introduce the type testing result of the VPI and no-VPI F insulation class form wound motor windings