DC MOTOR - Quiz

1) How to obtain opposite polarity in adjacent poles of a 4 pole DC motor?

Varying the number of turns in coil Making series connection of coils Making parallel connection of coils Making current flow in different direction

2) Which insulating material used in winding is a highly non -hygroscopic and possess good electrical strength?

Empire cloth Triplex paper Millinex paper Leatheroid paper

3) Calculate the average pitch (Y_A) for retrogressive wave winding, if No. of armature conductor = 14 No. of slots = 7 No. of poles = 2

4 6 8 14

4) Why the newly rewound armature must be preheated before varnishing?

Drive out the moisture from it Help for quick drying of varnish Make easy to penetrate varnish inside Maintain uniform spreading of varnishing

5) How the direction of rotation of a DC compound motor is changed?

By changing the direction of armature current By interchanging the supply terminals By changing the direction of both field and armature current By changing the direction of series field current