Question is ⇒ In Ward Leonard method of speed control of a D.C. motor, change in speed of motor is obtained by the, Options are ⇒ (A) change in armature voltage of D.C. motor, (B) change in the field excitation of the D.C. motor, (C) change in armature current of D.C. motor, (D) change in supply voltage, (E) , Leave your comments or Download question paper.

Question is ⇒ In Ward Leonard method of speed control of a D.C. motor, change in speed of motor is obtained by the, Options are ⇒ (A) change in armature voltage of D.C. motor, (B) change in the field excitation of the D.C. motor, (C) change in armature current of D.C. motor, (D) change in supply voltage, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	In Ward Leonard method of speed control of a D.C. motor, change in speed of motor is obtained by the
A.	change in armature voltage of D.C. motor [Correct Answer]
B.	change in the field excitation of the D.C. motor [Wrong Answer]
C.	change in armature current of D.C. motor [Wrong Answer]
D.	change in supply voltage [Wrong Answer]
View Answer 7 -5 Explanation:- Answer : A 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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⇒ The starting resistance of a D.C. motor is generally
low
around 500 ohms
1000 ohms
infinitely large

⇒ 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

⇒ 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

⇒ The speed of a D.C. shunt motor can be increased by
increasing the resistance in armature circuit
increasing the resistance in field circuit
reducing the resistance in the field circuit
reducing the resistance in the armature circuit

⇒ 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

⇒ 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

⇒ 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
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⇒ The type of D.C. motor used for shears and punches is
shunt motor.
series motor
differential compound D.C. motor
cumulative compound D.C. motor

⇒ Which of the following can be used for controlling the speed of a D.C. motor ?
Thermistor
Transistor
Thyratron
Thyristor

⇒ 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
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⇒ Voltage equation for D.C. motor is
Eb = V + IaRa
V = Eb + IaRa
Eb = V - Ia²Ra
V = Eb - IaRa

⇒ 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

⇒ 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

⇒ In a manual shunt motor starter
over load relay is connected in series and no volt relay in parallel with the load
over load relay is connected in parallel and no volt relay in series with the load
over load relay and no volt relay are both connected in series with the load
over load relay and no volt relay are both connected in parallel with the load

⇒ 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

⇒ The operation of electric generators and motors depend on the interaction between magnetic field and
copper conductors
electric field
electric current
commutator

⇒ 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
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⇒ In a D.C. generator all of the following could be the effects of iron losses except
Loss of efficiency
Excessive heating of core
Increase in terminal voltage
Rise in temperature of ventilating air

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

⇒ The plugging gives the
zero torque braking
smallest torque braking
highest torque braking
none of the above

⇒ 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

⇒ 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. 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

⇒ If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens
nothing will happen to the motor
this will make armature to take heavy current, possibly burning it
this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses
motor will run at very slow speed

⇒ In a D.C. motor constant torque is produced due to
rotor laminations
end-plates
pole shoes
commutator

⇒ While starting a differential compound motor, it is best to short the series field in order to avoid
excessive starting period
motor starting in wrong direction
tripping of the circuit breaker
large in rush of current

⇒ 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

⇒ 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

⇒ 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

⇒ 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.