DC MOTOR - Quiz

1) Why carbon composition brush requires in the armature circuit to operate the D.C motor?

Increases the starting torque Protects from armature reaction Protects armature from over loading Reduces the spark in the commutator segment

2) Why series motor produce high torque and speed initially without load?

Absence of back emf Load current flows through field winding Armature current and field current are same Series field winding wound with thick wire

3) Why the series field is short circuited at the time of starting in differential compound motor?

To reduce the starting current To increase the speed of motor To decrease the speed of motor To maintain proper direction of rotation

4) Which is the most effective method of balancing armature?

Static balancing Dynamic balancing Attached with counter balancing Plugged with lead weight balancing

5) Which material is used for starting resistance of DC starters?

Eureka Nichrome Manganin Constantine