1.A 200 V, d.c shunt machine has an armature resistance of 0.5 and field resistance of 200 . The machine is running at 1000

1.A 200 V, d.c shunt machine has an armature resistance of 0.5 Ω and field resistance of 200 Ω. The machine is running at 1000 rpm as a motor drawing 31 A from the supply mains. Calculate the speed at which the machine must be driven to achieve this as generator. *

a.1188.7 rmp

b.1155.5 rmp

c.1167.5 rmp

d.1177.5 rmp

2.A dc shunt motor drives an elevator load which requires a constant torque of 300 N.m. The motor is connected to a 600 V dc supply and the motor rotates at 1500 rpm. The armature resistance is 0.5. If the shunt field flux is reduced by 10 %, determine the armature current. *

a.93.9791 A

b.95.457 A

c.97.425 A

d.98.458 A

3.A single-phase, 240 V/2880 V ideal transformer is supplied from a 240 V source through a cable of resistance 3 ohm. If the load across the secondary winding is 720 ohm determine the power dissipated in the load resistance. *

a.4.8 Kw

b.4.5 Kw

c.5 Kw

d.3.5 Kw