Question is ⇒ Why are the D.C. motors preferred for traction applications ?, Options are ⇒ (A) Torque and speed are inversely proportional to armature current, (B) Torque is proportional to armature current, (C) Torque is proportional to square root of armature current, (D) The speed is inversely proportional to the torque and the torque is proportional to square of armature current, (E) , Leave your comments or Download question paper.

Question is ⇒ Why are the D.C. motors preferred for traction applications ?, Options are ⇒ (A) Torque and speed are inversely proportional to armature current, (B) Torque is proportional to armature current, (C) Torque is proportional to square root of armature current, (D) The speed is inversely proportional to the torque and the torque is proportional to square of armature current, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	Why are the D.C. motors preferred for traction applications ?
A.	Torque and speed are inversely proportional to armature current [Wrong Answer]
B.	Torque is proportional to armature current [Wrong Answer]
C.	Torque is proportional to square root of armature current [Wrong Answer]
D.	The speed is inversely proportional to the torque and the torque is proportional to square of armature current [Correct Answer]
View Answer 3 -1 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 :

⇒ The rated speed of a given D.C. shunt motor is 900 r.p.m. To run this machine at 1000 r.p.m., which of the following speed control scheme will be used ?
Ward-leonard control
Armature current resistance control
Field resistance control
None of the above

⇒ Hopkinson's test on D.C. machines is conducted at
no-load
part load
full-load
overload

⇒ 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

⇒ 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 mechanical power developed by a D.C. motor is equal to
power input + losses
back e.m.f. X armature current
power output X losses
power output X efficiency

⇒ The hysteresis loss in a D.C. machine least depends on
Frequency of magnetic reversals
Maximum value of flux density
Volume and grade of iron
Rate of flow of ventilating air

⇒ D.C. generators are normally designed for maximum efficiency around
full-load
rated r.p.m.
rated voltage
all of the above

⇒ The variable resistor shunting the field of a D.C. series motor is called a
armature divertor
voltage regulator
field divertor
potential divider

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

⇒ When the armature of a D.C. motor rotates, e.m.f. induced is
self-induced e.m.f.
mutually induced e.m.f.
back e.m.f.
none of the above

⇒ A shearing machine has cyclic load consisting of intermittent light and henry loads. Which of the following D.C. motor will be suitable for this purpose?
Series motor
Shunt motor
Cumulative compound motor
Differential compound motor

⇒ Which of the following motor has the poorest speed regulation ?
Shunt motor
Series motor
Differential compound motor
Cumulative compound motor

⇒ A D.C. series motor is that which
has its field winding consisting of thick wire and less turns
has a poor torque
can be started easily without load
has almost constant speed

⇒ Which motor has the poorest speed control?
Differentially compounded motor
Cumulatively compounded motor
Shunt motor
Series motor

⇒ Which D.C. motor Will have least percentage increase of input current for the same percentage increase in the torque?
Shunt motor
Series motor
Cumulative compound motor
Separately excited motor

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

⇒ If the terminals of armature of D.C. motor are interchanged, this action will offer following kind of braking
regenerative
plugging
dynamic braking
none of the above

⇒ In D.C. machines the residual magnetism is of the order of
2 to 3 per cent
10 to 15 per cent -
20 to 25 per cent
50 to 75 per cent

⇒ Regenerative method of braking is based on that
back e.m.f. is less than the applied voltage
back e.m.f. is equal to the applied voltage
back e.m.f. of rotor is more than the applied voltage
none of the above

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

⇒ Which of the following application requires high starting torque ?
Lathe machine
Centrifugal pump
Locomotive
Air blower

⇒ By looking at which part of the motor, it can be easily confirmed that a particular motor is D.C. motor?
Frame
Shaft
Commutator
Stator

⇒ 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.

⇒ 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%

⇒ 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

⇒ 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

⇒ VVhat is the effect produced by the electric current in an electric motor ?
Heating effect only
Magnetic effect only
Heating as well as magnetic effect
Heating as well as chemical effect

⇒ 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

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

⇒ Which D.C. motor has got maximum self relieving property ?
Series motor
Shunt motor
Cumulatively compounded motor
Differentially compounded motor