Correlation of Temperature Measurements on D-C Armatures [includes discussion]

The significance of the usual temperature measurements made on d-c armatures is somewhat vague, and the amount of published data on the subject is limited. This paper presents the results of a large number of laboratory tests showing the correlation among several different methods used for measuring temperatures on d-c armatures. It is believed that temperature measurements made with embedded thermocouples, read through slip rings, greatly enhance the validity of the correlations reported in this paper. Based on the data presented, it is concluded that temperature measurements made by careful resistance methods are more reliable and more nearly approximate the hot-spot values, than those made by thermometers. In the interest of brevity the scope is limited to the measurement of temperatures on the armature of d-c machines.