Question is ⇒ The speed of a D.C. series motor is, Options are ⇒ (A) proportional to the armature current, (B) proportional to the square of the armature current, (C) proportional to field current, (D) inversely proportional to the armature current, (E) , Leave your comments or Download question paper.

Question is ⇒ The speed of a D.C. series motor is, Options are ⇒ (A) proportional to the armature current, (B) proportional to the square of the armature current, (C) proportional to field current, (D) inversely proportional to the armature current, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	The speed of a D.C. series motor is
A.	proportional to the armature current [Wrong Answer]
B.	proportional to the square of the armature current [Wrong Answer]
C.	proportional to field current [Wrong Answer]
D.	inversely proportional to the armature current [Correct Answer]
View Answer 9 -12 Explanation:- Answer : D Discuss it below : Mohamed Omar Said on 2021-05-22 08:52:36 In which of the following applications DC series motor is used? Centrifugal Pump Motor Operation in DC and AC Water pump drive Starter for car !! OOPS Login [Click here] is required to post your answer/result Help other students, write article, leave your comments

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⇒ 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

⇒ Which of the following methods is most ecoriomical fol. finding the no-load losses of a large b.C. shunt motor ?
Retardation test
Swinburne's test
Hopkinson's test
none of the above

⇒ 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

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

⇒ If the field circuit of a loaded shunt motor is suddenly opened
torque developed by the motor would be reduced to zero
it would race to almost infinite speed
it would draw abnormally high armature current
the fuse or circuit breaker will open the circuit before too much damage is done to the motor

⇒ A face plate starter is employed for starting
induction motor
universal motor
synchronous motor
d.c. series motor

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

⇒ 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

⇒ Which of the following motors is most suitable for signalling devices and many kinds of timers ?
D.C. shunt motor
D.C. series motor
Induction motor
Reluctance motor

⇒ 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

⇒ Usually wide and sensitive speed control is desired in case of
centrifugal pumps
elevators
steel rolling mills
colliery winders

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

⇒ The series parallel system of speed control of D.C. series motors widely used in traction work gives a speed range of about
1 : 10
1 : 8
1 : 6
1 : 4

⇒ Which of the following methods gives the greatest breaking torque ?
Regenerative braking
Plugging
Rheostatic braking
None of the above.

⇒ 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

⇒ 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

⇒ 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.

⇒ A brake test on D.C. motors is usually restricted to
small horse power motors
variable speed motors
high speed motors
open frame type motors.

⇒ 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

⇒ Speed control by Ward Leonard method gives uniform speed variation
in one direction
in both directions
below normal speed only
above normal speed only

⇒ A series motor is' best suited for driving
machine tools
cranes and hoists
shear and punches
none of the above

⇒ Which D.C. motor will be suitable alongwith flywheel for intermittent light and heavy loads?
Series motor
Shunt motor
Cumulatively compounded motor
Differentially compounded motor

⇒ No-load speed of which of the following motor will be highest ?
Shunt motor
Series motor
Cumulative compound motor
Differentiate compound motor

⇒ 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

⇒ Field winding of a D.C. series motor is usually provided with thick wire
to provide large flux
to reduce the use of insulating materials
as it carries large load current
in order to reduce eddy current

⇒ 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

⇒ Which of the following is not necessarily the advantage of D.C. motors over A.C. motors ?
Better speed control
Low cost
High starting torque
Wide speed range

⇒ If Ia be the armature current, then speed of a D.C. shunt motor is
independent of la
proportional to Ia
varies as (la)²
varies as¹/_{I_a}

⇒ The speed of a D.C. shunt motor is required to be more than full load speed. This is possible by
reducing the field current
decreasing the armature current
increasing the armature current
increasing the excitation current

⇒ Which D.C. motor is preferred for elevators ?
Shunt motor
Series motor
Differential compoun.d motor
Cumulative compound motor