Question is ⇒ In a D.C. generator all of the following could be the effects of iron losses except, Options are ⇒ (A) Loss of efficiency, (B) Excessive heating of core, (C) Increase in terminal voltage, (D) Rise in temperature of ventilating air, (E) , Leave your comments or Download question paper.

Question is ⇒ In a D.C. generator all of the following could be the effects of iron losses except, Options are ⇒ (A) Loss of efficiency, (B) Excessive heating of core, (C) Increase in terminal voltage, (D) Rise in temperature of ventilating air, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	In a D.C. generator all of the following could be the effects of iron losses except
A.	Loss of efficiency [Wrong Answer]
B.	Excessive heating of core [Wrong Answer]
C.	Increase in terminal voltage [Correct Answer]
D.	Rise in temperature of ventilating air [Wrong Answer]
View Answer 8 -3 Explanation:- Answer : C Discuss it below : !! OOPS Login [Click here] is required to post your answer/result Help other students, write article, leave your comments

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⇒ Which of the following statement is incorrect ? If a starter is not used with large D.C. motor, it will draw a starting current which
will produce very low starting torque
will produce excessive line voltage drop
will damage the cOmmutator
is many times its full-load current

⇒ Which of the following steps is likely to result in reduction of hysteresis loss in a D.C. generator ?
Providing laminations in armature core
Providing laminations in stator
Using non-magnetic material for frame
Using material of low hysteresis coefficient for armature core material

⇒ The armature torque of the D.C. shunt motor is proportional to
field flux only
armature current only
both (a) and (b)
none of the above

⇒ The ratio of starting torque to fullload torque is least in case of
series motors
shunt motors
compound motors
none of the above

⇒ Speed control of a cumulatively compounded D.C. motor can be effected through change of
field resistance
armature resistance
armature voltage
any of the above

⇒ D.C. motor is to a drive a load which is almost nil for certain part of the load cycle and peak value for short duration. We will select this
series motor
shunt motor
compound motor
any of the above

⇒ The armature voltage control of D.C. motor provides
constant torque drive
constant voltage drive
constant current drive
none of the above

⇒ The purpose of retardation test on D.C. shunt machines is to find out
stray losses
eddy current losses
field copper losses
windage losses

⇒ As compared to an induction motor, the air gap in a D.C. motor is
less than 50%
between 50% and 90%
same
more

⇒ During rheostat braking of D.C. series motors
motor is run as a generator
motor is reversed in direction
motor is run at reduced speed

⇒ All motors, basically, operate on the principie of either repulsion or
induction
semi-conduction
capacitance
electro-magnetism

⇒ A motor for punching machine is usually subjected to
no load
continuous part load
continuous full load
intermittent load

⇒ The hysteresis loss in a D.C. generator varies with the frequency of magrietic reversals as
1/f
f
f^1.6
f²

⇒ Which motor should not be started on no-load ?
Series motor
Shunt motor
Cumulatively compounded motor
Differentially compounded motor

⇒ In which of the following applications D.C. series motor is invariably tried?
Starter for a car
Drive for a water pump
Fan motor
Motor operation in A.C. or D.C.

⇒ Following motor is used where high starting torque and wide speed range control is required.
Single phase capacitor start
Induction motor
Synchronous motor
D.C. motor

⇒ Which of the following losses are significantly reduced by laminating the core of a D.C. generator ?
Hysteresis losses
Eddy current losses
Copper losses
Windage losses

⇒ In a D.C. motor, the ratio Eb/Va indicates
running torque of the motor
starting torque of the motor
efficiency of the motor
speed regulation of the motor

⇒ Sparking is discouraged in a D.C. motor because
it increases the input power consumption
commutator gets damaged
both (a) and (b)
none of the above

⇒ Speed ,control by varying the armature circuit resistance, in a D.C. motor, provides a
constant torque drive
variable torque drive
constant power drive
variable power drive

⇒ The function of a field regulator for compound motors is to
control the flux
limit the armature current
demagnetise the field partially
none of the above

⇒ Which of the following loss in a D.C. generator is dissipated in the form of heat ?
Mechanical loss
Core loss
Copper loss
All of the above

⇒ D.C. generators are installed near the load centres to reduce
iron losses
line losses
sparking
corona losses

⇒ Compensating winding in a D.C. machine is placed
on yoke in the pole faces
on yoke in the interpolar gap
on armature
none of the above

⇒ The condition for maximum power in case of D.C. motor is
back e.m.f. = 2 x supply voltage
back e.m.f. = 1/2 x supply voltage
supply voltage = 1/2 x back e.m.f.
supply voltage = back e.m.f.

⇒ In case the conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be
1
around 90%
anywhere between 75% and 90%
less than 50%

⇒ Which D.C. motor will be preferred for cónstant speed line shafting ?
Cumulative compound motor
Differentially compound motor
Shunt motor
Series motor

⇒ Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be
level compounded
under compounded
cumulatively compounded
differentially compounded

⇒ Which motor should be used for centrifugal pumps ?
Series motor
Shunt motor
Either of the above
None of the above

⇒ If B_max is the maximum flux density, then eddy cu rrent loss will vary as
B_max
(B_max)²
(B_max)^1.2
(B_max)^2.4