The Armette Test for Evaluating Universal Motor Insulation Systems

The "armette test" was devised to improve the quality of test data and reduce the cost of obtaining it. Test methods to date require the manufacture of an entire motor. Present data can be unduly influenced or even voided should the field change or failure occur during the test. The "armette" is a unit that consists of a simple shaft, laminations, magnet wire, insulation, and varnish. It differs from the standard armature in that it has fewer coils, no commutator, and no fan. When assembled in the test setup it makes use of a built-in fan and slip ring assembly for cooling and electrical connections. The armette test consists of mounting the armette in a fixture, connecting the leads to the slip ring, and starting the cyclic test. The cyclic test contains a stationary heating period, a high-speed spin, an electrical surge test, a coast-to-stop period, and a hypot test. The time for each part of the cycle and the input voltage for the heating period are the controlled variables for the test. The work done and correlations run in developing an armette test are presented. Results obtained indicate that the armette test produces data which correlate with present stall test data.