The Diseases Of Electrical Machinery

38 THE DISEASES OF looo times as great as that of the series winding, one may say that the shunt winding is completely short- circuited. Practically no current will flow through it, ånd the machine will not excite itself, since the two poles of the armature are short-circuited. Such a short- circuit entirely prevents the working of a dynamo. With an electric motor it is equivalent to a direct short-circuit across the mains. A further possibility is a contact between the end of the shunt winding and the beginning of the series -AWWvVML- Fig. i8. Fig. 19. winding, as in Fig. 18. This has obviously the same effect as a short-circuit between the negative lead and the negative brush spindle. The result, when the short-circuit path is itself of very small resistance indeed, is only that the series coil is short-circuited. The machine will then work as a shunt machine with- out affecting the working any further. A harmless short-circuit is one between the two coils, between the end of the shunt and the end of the series winding. It is evident that such a short-circuit