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EXPERIMENT 1: DC MACHINE CONSTRUCTIONAL FEATURES & STARTER

Total questions: 15

Worksheet time: 11mins

Name
Class
Date
1.

The Current flowing through the armature of the dc motor is:

a)

DC

b)

AC

c)

Pulsating

d)

None of the Answers

2.

_________ field winding has small number of turns of thick

copper wire.

a)

Shunt

b)

Series

c)

Compund

d)

Separately excited

3.

In DC Generator which of the following device plays a key role in providing dc current:

a)

Commutator

b)

Equalizer rings

c)

Brushes

d)

Dummy Coils

4.

In which mode machine is operating, given that conductor

current is in the same direction of conductor emf?

a)

Motoring

b)

Generating

c)

Can’t be determined using directions

d)

In both modes for different cycles

5.

Name one factor that does not affect the size of a force in on a current-carrying conductor placed in a magnetic field?

a)

Gravity

b)

Magnetic flux density/size of magnetic field

c)

Size of the current

d)

Length of the conductor

6.

What angle must there be between a magnetic field and a conductor in order for the maximum force to be exerted?

a)

180

b)

45

c)

270

d)

90

7.

Emf and torque produced in a DC machine are proportional to________ and _________ respectively.

a)

Armature speed and armature emf

b)

Armature emf and armature speed

c)

Armature current and armature emf

d)

Armature speed and armature current

8.

Starter is used in DC motor for which of the following purpose:

a)

improving back emf

b)

improving starting torque

c)

improving efficiency

d)

reducing starting current

9.

For what type of applications the lap winding is used in DC

generators:

a)

high current applications

b)

high power applications

c)

high voltage applications

d)

high frequency applications

10.

The power rating that is indicated on name plate of any motor is:

a)

gross power

b)

output power of shaft

c)

power drawn in kVA

d)

net power

11.

Which type of power supply is given to Generator Field winding:

a)

pulsating DC supply

b)

AC supply

c)

DC supply

d)

none of these

12.

The armature core is mounted on .................. of the DC generator:

a)

slots

b)

shaft

c)

yoke

d)

pole shoe

13.

In three-point starter, as a starting handle is rotated __________

a)

The resistance is added into armature circuit

b)

The resistance is removed from field circuit

c)

The resistance is removed into armature circuit

d)

Resistance is neither added nor removed

14.

Which of the following is not required in DC generator to

generate DC Voltage?

a)

conductor

b)

Slip ring

c)

Prime mover

d)

Magnetic Field

15.

Where is field winding mounted in a DC machine?

a)

Stator

b)

Rotor

c)

Anywhere on stator or rotor

d)

Absent