Question is ⇒ Which D.C. motor will be preferred for machine tools ?, Options are ⇒ (A) Series motor, (B) Shunt motor, (C) Cumulative compound motor, (D) Differential compound motor, (E) , Leave your comments or Download question paper.

Question is ⇒ Which D.C. motor will be preferred for machine tools ?, Options are ⇒ (A) Series motor, (B) Shunt motor, (C) Cumulative compound motor, (D) Differential compound motor, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	Which D.C. motor will be preferred for machine tools ?
A.	Series motor [Wrong Answer]
B.	Shunt motor [Correct Answer]
C.	Cumulative compound motor [Wrong Answer]
D.	Differential compound motor [Wrong Answer]
View Answer 6 -4 Explanation:- Answer : B 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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⇒ 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

⇒ D.C. generators are normally designed for maximum efficiency around
full-load
rated r.p.m.
rated voltage
all 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 speed of a D.C. motor, under constant load conditions, is affected by
back e.m.f.
field flux
armature current
none of the above

⇒ 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.

⇒ The retardation test is applicable to shunt motors and generators and is used to find
the copper losses
the stray losses
the friction losses
the eddy current losses

⇒ 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

⇒ 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

⇒ Which of the following D.C. motors has the least drop in speed between no-load and nominal load ?
Series motor without commutating poles
Series motor with commutating poles
Shunt motor with commutating pole
Compound motor without commutating poles

⇒ If T_a be the torque and Ia the armature current for a D.C. motor, then which of the following relation is valid before saturation ?
T_a ∝ I_a
T_a ∝ I/I_a
T_a ∝ I_a²
T_a ∝ ^I/_{I_a²}

⇒ Which losses can be determined by performing the retardation test ?
Friction losses
Eddy current losses
Stray losses
Copper losses

⇒ 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

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

⇒ The speed of a D.C. motor can be varied by varying
field current
applied voltage
resistance in series with armature
any of the above

⇒ 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

⇒ When two D.C. series motors are connected in parallel, the resultant speed is
more than the normal speed
loss than the normal speed
normal speed
zero

⇒ 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

⇒ A three point starter is considered suitable for
shunt motors
shunt as well as compound motors
shunt, compound and series motors
all D.C. motors

⇒ A D.C. motor can be easily identified by
winding
commutator
size of conductor
yoke

⇒ Why are the D.C. motors preferred for traction applications ?
Torque and speed are inversely proportional to armature current
Torque is proportional to armature current
Torque is proportional to square root of armature current
The speed is inversely proportional to the torque and the torque is proportional to square of armature current

⇒ 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

⇒ A D.C. shunt motor is rotating in clockwise direction as viewed from one end. The polarity of connection of the armature and field winding are reversed simultaneously. The motor will
rotate in clockwise direction
rotate in anti-clockwise direction
will not rotate at all
gain excessively high speed

⇒ What will happen if supply terminals of D.C. shunt motor are interchanged ?
The direction of rotation will reverse
Motor will stop
Motor will run at speed lower than the normal speed in the same direction
Motor will run at its normal speed in the same direction as it was running

⇒ 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

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

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

⇒ In a D.C. shunt motor, speed is
independent of armature current
directly proportional to the armature current
proportional to the square of the current
inversely proportional to the armature current

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

⇒ Which of the following method of speed control, of D.C. machine will offer minimum efficiency ?
Voltage control method
Field control method
Armature control method
All above methods

⇒ In a D.C. motor, unidirectional torque is produced with the help of
end plates
bushes
commutator
both (b) and (c)