The Surge Comparison Testing of Several Types of D-C Armature Windings

The purpose of these tests was twofold: 1. To point out those portions of a d-c armature winding which are most severely stressed during surge comparison testing. 2. To present a rapid and simple method for the detection and identification of most types of winding faults which may be present in a d-c armature winding because of insulation damage or faulty construction. In order to accomplish the first purpose of this test, the surge voltage distribution was measured in: An unsymmetrical 2-layer 2-pole lapwound armature (see armature 1 of Table I). A balanced 2-layer 4-pole wave-wound armature as described in Table I as being armature no. 2. A balanced 2-layer 4-pole lap-wound armature having cross connections at the commutator (see armature no. 3 of Table I). In order to accomplish the second purpose of these tests, many armatures were surge tested and in some cases deliberate faults were introduced. This was done in order to identify and classify the types of faults generally encountered in 2-pole and 4-pole windings. The faults that were investigated include: bar-tobar short circuits (1), ground short circuits (2), short circuits between coil layers (3), and open-circuited windings (4).