Electrical Machines
A dc shunt generator, when driven without any excitation, showed an open circuit voltage of 12 V. When the field winding was excited, the voltage dropped to zero. It happened because

 field resistance was higher than critical resistance
 there was no residual magnetism in the field circuit
 field winding was wrongly connected
 there was a break in the armature circuit

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
The results of a slip test for determining direct axis (Xd) and quadrature axis (Xq) reactances of a star connected salient pole alternator are given below Phase values: Vmax = 108 V ; Vmin = 96 V Imax = 12 A ; Imin = 10 A Hence the two reactances will be

 Xd = 9.6Ω and Xq = 9Ω
 Xd = 10.8Ω and Xq = 8Ω
 Xd = 8Ω and Xq = 10.8Ω
 Xd = 9Ω and Xq = 9.6Ω

ANSWER DOWNLOAD EXAMIANS APP