Electrical Machines
An 8 pole DC generator has 500 armature conductors and useful flux per pole of 0.065 Wb. What will be the emf generated if it is lap connected and runs at 1000 rpm. What must be the speed at which it is driven to produce the same emf if it is wave wound?

 2166.67V, 230 rpm.
 541.67V, 250 rpm.
 2166.67V, 270 rpm.
 541.67V, 200 rpm.

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
A compound dc generator is delivering full load current at a terminal voltage of 230 V. Its series-field winding gets short circuited. If its terminal voltage 1. becomes more than 230 V, it is overcompounded generator 2. becomes more than 230 V, it is differentially compounded generator 3. becomes less than 230 V, it is overcompounded generator 4. becomes less than 230 V, it is differentially compounded generator 5. becomes less than 230 V, it is level compounded generator From these, the correct answer is

 1, 4
 1, 4, 5
 2, 3, 5
 2,3

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
In dc machines, the field system has to be provided on stator unlike synchronous machines Where in it could be on any member, because

 it reduces field structure iron losses
 dc machines are comparatively low rating machines.
 commutator action is not possible otherwise
 it gives more uniform air-gap flux distribution

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
When the supply terminal of a DC shunt motor are interchanged

 The direction of rotation will reverse.
  The motor will run at its normal speed in the same direction as before.
 The motor will run much faster in the same direction.
 The motor will stop.

ANSWER DOWNLOAD EXAMIANS APP
MORE MCQ ON Electrical Machines