The Diseases Of Electrical Machinery

36 THE DISEASES OF posed to occur between the iron frame of a bipolar machine and the copper cable or link connecting to- gether the two magnet-coils. The frame is assumed to be earthed, and the negative conductor also earthed. In this case, the right-hand magnet-coil is completely cut out of circuit. The effect of such a short-circuit will be different according to the point in the winding where contact occurs. Contaet between the Thin Wire and the Thick Wire Winding.—In the case of compound-wound machines, short-circuits between the two windings may occur. With regard to the result of these, it depends entirely upon the position where they occur. The general scheme of a compound machine is given in Fig. 14. The thick line represents the series (thick wire) winding, and the thin line the shunt (thin wire) Fig. 14. Fig. 15. winding. The connections can also be made as in Fig. 15 where the shunt winding is connected directly across to the armature. The only difference lies in the faet that in the first case the shunt current flows