Question is ⇒ Hopkinson's test on D.C. machines is conducted at, Options are ⇒ (A) no-load, (B) part load, (C) full-load, (D) overload, (E) , Leave your comments or Download question paper.

Question is ⇒ Hopkinson's test on D.C. machines is conducted at, Options are ⇒ (A) no-load, (B) part load, (C) full-load, (D) overload, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	Hopkinson's test on D.C. machines is conducted at
A.	no-load [Wrong Answer]
B.	part load [Wrong Answer]
C.	full-load [Correct Answer]
D.	overload [Wrong Answer]
View Answer 5 -2 Explanation:- Answer : C 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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Also Read Similar Questions Below :

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

⇒ 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

⇒ The mechanical power developed by a shunt motor will be maximum when the ratio of back e.m.f. to applied voltage is
4.0
2.0
1.0
0.5

⇒ 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

⇒ Which of the following motors have almost constant speed over their full load range ?
A.C. series motors
D.C. series motors
D.C. shunt motors
Low resistance squirrel cage motors

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

⇒ Which of the following motors is usually used in house-hold refrigerators ?
D.C. shunt motor
D.C. series motor
Single phase induction motor (split phase start or induction run motor)
Reluctance motor

⇒ 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

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

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

⇒ 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

⇒ 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

⇒ 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

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

⇒ The speed of a D.C. series motor is
proportional to the armature current
proportional to the square of the armature current
proportional to field current
inversely proportional to the armature current

⇒ Which of the following methods of braking is used in rolling mills ?
Dynamic braking
Plugging
Regenerative braking
Mechanical brakes

⇒ 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

⇒ In a motor, energy conversion would not have been possible but for the
production of opposing back e.m.f. Eb in the armature
input energy from supply
use of commutator
application of Fleming's left-hand rule

⇒ The speed of a D.C. shunt motor more than its full-load speed can be obtained by
decreasing the field current
increasing the field current
decreasing the armature current
increasing the armature current

⇒ 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 case of D.C. shunt motors the speed is dependent on back e.m.f. only because
back e.m.f. is equal to armature drop
armature drop is negligible
flux is proportional to armature current
flux is practically constant in ac. shunt motors

⇒ 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

⇒ During rheostatic braking the braking torque is proportional to
speed
(speed)²
(speed)^-1
(speed)^-2

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

⇒ 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

⇒ A 230 V D.C. shlint motor takes 32 A at full load. The back e.m.f. on full load, if the resistance of motor armature and shunt field windings are 0.2 Ω and 115 Ω respectively, will be
210 V
215 V
220 V
224 V

⇒ 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

⇒ 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 purpose of retardation test on D.C. shunt machines is to find out
stray losses
eddy current losses
field copper losses
windage losses

⇒ 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