DC MOTOR - Quiz

1) Why shunt field coil is connected in series with holding coil in D.C three point starter?

Increase the holding coil current Decrease the holding coil current Protect the shunt field from over current Protect the motor in case of open in shunt field

2) Why the direction of rotation is changed only by changing the armature current direction in a D.C compound motor?

Maintain rated speed Maintain motor characteristics Avoid armature reaction effect Prevent motor from over loading

3) Which speed control methods offers below normal speed in DC shunt motor?

Field control method Voltage control method Armature control method Ward Leonard system of speed control

4) Why starters are required to start D.C motors in industries?

Regulate the field voltage Reduce the armature current Control the armature reaction Smooth operation of motors

5) Which insulating material belongs to class ?B? insulation?

Cotton Bamboo Fiber glass Leatheroid paper