Question is ⇒ Starters are used with D.C. motors because, Options are ⇒ (A) these motors have high starting torque, (B) these motors are not self-starting, (C) back e.m.f. of these motors is zero initially, (D) to restrict armature current as there is no back e.m.f. while starting, (E) , Leave your comments or Download question paper.

Question is ⇒ Starters are used with D.C. motors because, Options are ⇒ (A) these motors have high starting torque, (B) these motors are not self-starting, (C) back e.m.f. of these motors is zero initially, (D) to restrict armature current as there is no back e.m.f. while starting, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	Starters are used with D.C. motors because
A.	these motors have high starting torque [Wrong Answer]
B.	these motors are not self-starting [Wrong Answer]
C.	back e.m.f. of these motors is zero initially [Wrong Answer]
D.	to restrict armature current as there is no back e.m.f. while starting [Correct Answer]
View Answer 9 -8 Explanation:- Answer : D 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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Also Read Similar Questions Below :

⇒ If the supply voltage for a D.C. motor is increased, which of the following will decrease ?
Starting torque
Operating speed
Full-load current
All of the above

⇒ Which one of the following is not the function of pole shoes in a D.C. machine ?
To reduce eddy current loss
To support the field coils
To spread out flux for better uniformity
To reduce the reluctance of the magnetic path

⇒ 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

⇒ The speed of a motor falls from 1100 r.p.m. at no-load to 1050 r.p.m. at rated load. The speed regulation of the motor is
0.0236
0.0476
0.0677
0.0884

⇒ Regenerative braking on shunt motors is used when
the load is variable
the load is constantly decreasing
the load acts as a braking force
the load has overhauling characteristics.

⇒ For which types of D.C. motor, dynamic braking is generally used ?
Shunt motors
Series motors
Compound motors
All of the above

⇒ Which D.C. motor is generally preferred for cranes and hoists ?
Series motor
Shunt motor
Cumulatively compounded motor
Differentially compounded motor

⇒ Which of the following loss of D.C. motor decreases with increase in load ?
Friction and windage loss
Core loss
Brush contact loss
none of the above

⇒ When the electric train is moving down a hill the D.C. motor act as
D.C. series generator
D.C. shunt generator
D.C. shunt motor
D.C. series motor

⇒ For constant torque drive which speed control method is preferred ?
Field control
Armature voltage control
Shunt armature control
Mechanical loading system

⇒ Speed control by the variation of flux, in a D.C. shunt motor, will give
constant torque drive
variable torque drive
constant power drive
variable power drive

⇒ A direct on line starter is used for starting motors
up to 5 H.P.
up to 10 H.P.
up to 15 H.P.
up to 20 H.P.

⇒ Starters are used with D.C. motors because
these motors have high starting torque
these motors are not self-starting
back e.m.f. of these motors is zero initially
to restrict armature current as there is no back e.m.f. while starting

⇒ In a differentially compounded D.C. motor, if shunt field suddenly opens
the motor will first stop and then run in opposite direction as series motor
the motor will work as series motor and run at slow speed in the same direction
the motor will work as series motor and run at high speed in the same direction
the motor will not work and come to stop

⇒ If a D.C. motor is to be selected for conveyors, which motor would be preferred ?
Series motor
Shunt motor
Differentially compound motor
Cumulative compound motor

⇒ Which of the following methods of braking is used in rolling mills ?
Dynamic braking
Plugging
Regenerative braking
Mechanical brakes

⇒ Regenerative braking on D.C. shunt motors is used when
the load has overhauling characteristics
the load is variable
the load also acts as a braking force
the load is constantly decreasing

⇒ Which of the following motor has high starting torque ?
Synchronous motor
A.C. series motor
D.C. series motor
Induction motor

⇒ 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

⇒ During rheostatic braking the braking torque is proportional to
speed
(speed)²
(speed)^-1
(speed)^-2

⇒ In D.C. shunt motors as load is reduced
the speed will increase abruptly
the speed will increase in proportion to reduction in load
the speed will remain almost constant
the speed will reduce

⇒ The current drawn by the armature of D.C. motor is directly proportional to
the torque required
the speed of the motor
the voltage across the terminals
none of the above

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

⇒ Which of the following motors have almost constant speed over their full load range ?
A.C. series motors
D.C. series motors
D.C. shunt motors
Low resistance squirrel cage motors

⇒ For which of the following applications a D.C. motor is preferred over an A.C. motor ?
Low speed operation
High speed operation
Variable speed operation
Fixed speed operation

⇒ Hopkinson's test is conducted at
no load
part load
low load
full load

⇒ Ward-Leonard control is basically a
voltage control method
field divertor method
field control method
armature resistance control method

⇒ In a D.C. generator, the iron losses mainly take place in
yoke
commutator
armature conductors
armature rotor

⇒ Buses, trains, trolleys, hoists, cranes require high starting torque and therefore make use of
D.C. series motor
D.C. shunt motor
induction motor
all of above motors

⇒ If the no-voltage release of a D.C. motor starter fails to work on resumption of supply after a break, the motor will
not start automatically
start automatically without trouble
get damaged
develop very low torque