The Diseases Of Electrical Machinery

ELECTRIC AL MACHINERY. 37 also through the series coils, and that in the second case it does not. Let us first keep to Fig. 14. Here a short-circuit or point of contact between the two wires may occur in different places. Fig. 16 shows a Fig. 16. Fig. 17. case where the middle of the shunt winding is in con- tact with one point of the series winding. The result is that half of the shunt current conveys no current. This fault shows itself in action in the same way as the previously mentioned fault, where some of the coils were bridged over. In the case of multipolar machines, working will be entirely stopped. In the case of bi- polar machines, working will in general not be entirely prevented, but owing to the heavy current one coil will become very hot while the other remains cool. Fig. 17 shows a short-circuit between the com- mencement of the shunt winding and the beginning of the series winding. In this case the entire shunt winding is thus put in parallel with the series winding Since the resistance of the shunt winding will be about