QUIZ3-EM1

If a DC motor is connected to AC supply what will happen then?

• Not run

• Burn

• Run at normal speed

• Run at extremely low speed

Function of yoke is to provide the return path for magnetic flux.

• True

• False

In a DC machine, rectification process is carried out in order to get unidirectional output (DC). This rectification process is carried out by

• Half wave rectifier

• Full wave rectifier

• Mechanical rectification

• Centre tapped rectifier

What is the effect of armature coils at points where brushes are located?

• Induces positive emf

• Induces negative emf

• Induces zero emf

• Depends on the speed of rotor

Coil span for 4-pole, 12-slot armature winding is

• 24

• 48

• 8

• 3

For a 2-pole DC machine with coil span equal to 6, what are the number of commutator segments?

• 3

• 12

• 4

• 8

When coil sides are pole pitch apart, the DC armature winding is called as ___________

• Multiplex

• Fractional-pitch

• Full-pitch

• Simplex

Resultant pitch in the lap winding is__________

• Depends on Yb value

• Depends on Yf value

• Depends on Yb and Yf value

• Always equal to 2

What is the condition of retrogressive winding?

• Yb > Yf

• Yb < Yf

• Yb = Yf

• No condition in terms of Yb and Yf

What is the relation between conductor current and armature current in wave winding?

• Ic = Ia

• Ic = 2Ia

• Ic = 4Ia

• Ic = Ia/2