Question is ⇒ Speed control of a cumulatively compounded D.C. motor can be effected through change of, Options are ⇒ (A) field resistance, (B) armature resistance, (C) armature voltage, (D) any of the above, (E) , Leave your comments or Download question paper.

Question is ⇒ Speed control of a cumulatively compounded D.C. motor can be effected through change of, Options are ⇒ (A) field resistance, (B) armature resistance, (C) armature voltage, (D) any of the above, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	Speed control of a cumulatively compounded D.C. motor can be effected through change of
A.	field resistance [Wrong Answer]
B.	armature resistance [Wrong Answer]
C.	armature voltage [Wrong Answer]
D.	any of the above [Correct Answer]
View Answer 11 -2 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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⇒ 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

⇒ 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

⇒ 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

⇒ 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

⇒ If conditions for maximum power for a D.C. motor are established, the efficiency of the motor will be
less than 50%
60 to 70%
80 to 90%
1

⇒ 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

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

⇒ Sparking is discouraged in a D.C. motor because
it increases the input power consumption
commutator gets damaged
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none of the above

⇒ The generated e.m.f. and the current are in the opposite direction in case of
d.c. generators
d.c. motors
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none of the above

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

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

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

⇒ A series motor is started without load. The effect is that
the back e.m.f. decreases
the torque increases rapidly
the speed increases rapidly
the current drawn increases rapidly

⇒ In hazardous area of gassy mines, material transportation is done by vehicles powered by
A.C. mains
D.C. mains
I.C. engines
batteries

⇒ Which D.C. motor will be preferred for cónstant speed line shafting ?
Cumulative compound motor
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⇒ The main disadvantage of Hopkinson's test for finding efficiency of the shunt D.C. motors is that it
needs one motor and one generator
requires two identical shunt machines
requires full-load power
ignores any change in iron loss

⇒ In an overloaded motor main danger arises due to
winding getting overheated
busbars getting heated
starter getting damaged
bearings getting overheated

⇒ 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 motors one will choose to drive the rotary compressor ?
D.C. shunt motor
D.C. series motor
Universal motor
Synchronous motor

⇒ In D.C. motor which of the following can sustain the maximum temperature rise?
Slip rings
Commutator
Field winding
Armature winding

⇒ If a D.C. motor is connected across the A.C. supply it will
run at normal speed
not run
run at lower Speed
burn due to heat produced in the field winding by eddy currents

⇒ D.C. motor is to drive a load which has certain minimum value for most of the time and some peak value for short duration. We will select the
series motor
shunt motor
compound motor
any of the above

⇒ In a D.C. motor if the back e.m.f. is absent
motor will burn
motor will not run at all
motor will run at very slow speed
motor will run at very high speed

⇒ 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

⇒ If the field of a D.C. shunt motor gets opened while motor is running
the speed of motor will be reduced
the armature current will reduce
the motor will attain dangerously high speed
the motor will continue to run at constant speed

⇒ 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}

⇒ Which of the following tests will be suitable for testing two similar D.C. series motors of large capacity ?
Swinburne's test
Hopkinson's test
Field test
Brake test

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

⇒ For the same H.P. rating and full load speed, following motor has poor starting torque
shunt
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