Alternator Questions And Answers
Questions and Answers related to Alternator are most important question for competitive exams and in GATE examination which is most important in electrical machine.
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Alternator Questions And Answers |
MCQS ( Alternator )
Q.1
The rotor preferred for alternators applied to hydraulic turbines are
(a)salient pole type
(b)cylindrical rotor type
(c)solid rotor type
(d)any of the above
Ans.
(a)salient pole type
Q.2
The frequency of voltage generated in
large alternators is
(a)50 Hz
(b)60 Hz
(c)in kilo cycles
(d)in mega cycles
Ans.
(a)50 Hz
Q.3
Which of the following prime mover is
less efficient?
(a)Gas turbine
(b)Petrol engine
(c)Diesel engine
(d)Steam engine
Ans.
(d)Steam engine
Q.4
In which coil the harmonic component
of the generated e.m.f. will be more?
(a)Full pitch coil
(b)Short pitch coil
(c)Long pitch coil
(d)Same in all coils
Ans.
(a)Full pitch coil
Q.5
In case of turbo-alternators the rotor is
usually made of
(a)cast iron
(b)forged steel
(c)laminated stainless steel
(d)manganese steel
Ans.
(b)forged steel
Q.6
The number of poles in turbo alternators is usually
(a)0.2
(b)4
(c)12
(d)50
Ans.
(a)0.2
Q.7
In huge alternators ,the moving part is
(a)brushes
(b)poles
(c)armature
(d)none of the above
Ans.
(b)poles
Q.8
In power generating stations(Thermal
stations),the usual number of poles
employed in alternators are
(a)twenty four
(b)thirty two
(c)forty eight
(d) none of these
Ans.
(d) none of these
Q.9
Harmonic component of generated e.m.f.
will be more in
(a)short pitch coil
(b)full-pitch coil
(c)long-pitch coil
(d)none of above coils
Ans.
(b)full-pitch coil
Q.10
When a three-phase alternator supplies
capacitive load, armature reaction flux
will be
(a)opposing the main magnetic field
(b)helping the main magnetic field
(c)either(a)or(b)
(d)none of the above
Ans.
(b)helping the main magnetic field
Q.11
What kind of rotor is most suitable for
turbo-alternators which are designed
to run at high speed?
(a)Salient pole type
(b)Non-salient pole type
(c)Either(a)or(b)
(d)None of the above
Ans.
(b)Non-salient pole type
Q.12
Modern 3-phase alternator of a central
power station will have generated volt-
age of
(a)132kV
(b)11kV
(c)400V
(d)230V
Ans.
(b)11kV
Q.13
The speed of a salient pole machine is
nearly
(a)500r.p.m.
(b)1000r.p.m.
(c)1500r.p.m.
(d)3000r.p.m.
Ans.
(a)500r.p.m.
Q.14
Where the terminal voltage of an alter-
nator falls on throwing of the load, it
indicates that the load is purely
(a)resistive
(b)capacitive
(c)inductive
(d)none of the above
Ans.
(c)inductive
Q.15
Alternators are usually designed to
generate
(a)definite currents
(b)definite power factor
(c)variable frequencies
(d) definite frequencies
Ans.
(d) definite frequencies
