Abstract :
TEST PROCEDURES for determining the relative life expectancies of different insulation systems for random-wound machines, using either complete motors or models, called motorettes, are provided for by AIEE no. 510.1 The procedure calls for subjecting the motorettes to successive periods of high temperature in ovens, followed by vibration and exposure to moisture, and an overvoltage check. The cycle is repeated until the test unit fails under voltage. The tests are conducted at three or more temperatures, and are made on a sufficient number of samples to obtain the desired statistical accuracy. The tests on motors are similar, but the heating, vibration, and voltage exposures are all obtained at the same time by operating the motors on a frequent starting or reversing cycle. The results of the tests are given in the form of a life-temperature chart, as in Fig. 1.
