Question 1

In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when

Accepted Answer

A) r.p.m. is more than 300 
B) r.p.m. is less than 300 
C) number of poles is 4 
D) number of poles is 2

Question 2

In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralised by all of the following except

Accepted Answer

A) interpoles 
B) dummy coils 
C) compensating winding 
D) shifting of axis of brushes

Question 3

The rapid wear of brushes takes place due to

Accepted Answer

A) abrasion from dust 
B) excessive spring pressure 
C) rough commutator bars 
D) all of the above factors

Question 4

Interpole flux should be sufficient to

Accepted Answer

A) neutralise the commutating self induced e.m.f. 
B) neutralise the armature reaction flux 
C) neutralise both the armature reaction flux as well as commutating e.m.f. induced in the coil 
D) perform none of the above functions

Question 5

The purpose of providing dummy coils in a generator is

Accepted Answer

A) to reduce eddy current losses 
B) to enhance flux density 
C) to amplify voltage 
D) to provide mechanical balance for the rotor

Exam 13: D.C Generator Operation and Construction

In a D.C. generator the number of mechanical degrees and electrical degrees will be the same when

In a D.C. generator in order to reduce sparking at brushes, the self-induced e.m.f. in the coil is neutralised by all of the following except

The rapid wear of brushes takes place due to

Interpole flux should be sufficient to

The purpose of providing dummy coils in a generator is