Question is ⇒ If Ia be the armature current, then speed of a D.C. shunt motor is, Options are ⇒ (A) independent of la, (B) proportional to Ia, (C) varies as (la)2, (D) varies as1/Ia, (E) , Leave your comments or Download question paper.

Question is ⇒ If Ia be the armature current, then speed of a D.C. shunt motor is, Options are ⇒ (A) independent of la, (B) proportional to Ia, (C) varies as (la)2, (D) varies as1/Ia, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	If Ia be the armature current, then speed of a D.C. shunt motor is
A.	independent of la [Correct Answer]
B.	proportional to Ia [Wrong Answer]
C.	varies as (la)² [Wrong Answer]
D.	varies as¹/_{I_a} [Wrong Answer]
View Answer 15 -10 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

Previous question Next question

Also Read Similar Questions Below :

⇒ Four point starter in the D.C. motor is used
to decrease the field current
to increase the field current
not to effect the current passing through Hold on coil even if any change M the field current takes place
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

⇒ Which of the following tests can be conducted on all types of D.C. machines ?
Hopkinson's test
Running down test
Block rotor test
Field's test

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

⇒ In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will
remain unchanged
reduce to one-fourth value
increase four folds
be doubled

⇒ 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

⇒ If a D.C. shunt motor is working at full load and if shunt field circuit suddenly opens
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
nothing will happen to motor
motor will come to stop

⇒ Differentially compound D.C. motors can find applications requiring
high starting torque
low starting torque
variable speed
frequent on-off cycles

⇒ Which of the following tests can be used to determine no-load losses in a D.C. shunt motor ?
Running down test
Swinburne's test
Field test
Brake test

⇒ The armature shaft of a D.C. motor must be able to withstand
any unbalanced magnetic pull on the armature core
twisting strains due to transmission of torque
bending moment due to the weight of the armature and commutator
all of the above

⇒ In Ward-Leonard control the lower limit of speed is imposed by
residual magnetism of the generator
core losses of motor
mechanical losses of motor and generator together
all of the above

⇒ If t be the thickness of the laminations, then eddy current loss in a generator. will vary as
¹/_t
¹/_t²
t
t²

⇒ 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

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

⇒ 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

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

⇒ 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

⇒ 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

⇒ 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

⇒ For a D.C. shunt motor if the excitation is changed
torque will remain constant
torque will change but power will remain constant
torque and power both will change
torque, power and speed, all will change

⇒ 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.

⇒ 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

⇒ If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor
of lower H.P. should be selected
of higher H.P. should be selected
can be used for 50°C ambient temperature also
is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor

⇒ 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

⇒ 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

⇒ 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%

⇒ In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be
almost negligible
rated full-load current
less than full-load current
more than full-load current

⇒ In case of a shunt motor if the supply voltage is increased by 10%, which of the following will decrease ?
full load current
full load speed
starting torque
none of the above

⇒ D.C. generators are installed near the load centres to reduce
iron losses
line losses
sparking
corona losses

⇒ In Field's test for series motors one motor drives the other machine as
cumulative compound generator
differential compound generator
separately excited generator
series generator