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Home⇒ Engineering⇒
Dc motors
1-Dont try to cram or spend more time here just read it fast and cover syllabus then practice MCQ's cheptor of same topic to check your progress. . |
2-Wrong options are also given but dont concentrate there, Right answer is in bold format. |
Q21 ⇒ Which of the following tests can be used
to determine no-load losses in a D.C.
shunt motor ? Swinburne's test [other wrong options] [Discuss in forum] Running down test Field test Brake test |
Q22 ⇒ No-load speed of which of the following
motor will be highest ? Series motor [other wrong options] [Discuss in forum] Shunt motor Cumulative compound motor Differentiate compound motor |
Q23 ⇒ If the field of a D.C. shunt motor gets
opened while motor is running the motor will attain dangerously high speed [other wrong options] [Discuss in forum] the speed of motor will be reduced the armature current will reduce the motor will continue to run at constant speed |
Q24 ⇒ The speed of a D.C. shunt motor more
than its full-load speed can be
obtained by decreasing the field current [other wrong options] [Discuss in forum] increasing the field current decreasing the armature current increasing the armature current |
Q25 ⇒ By looking at which part of the motor,
it can be easily confirmed that a
particular motor is D.C. motor? Commutator [other wrong options] [Discuss in forum] Frame Shaft Stator |
Q26 ⇒ Which of the following law/rule can
he used to determine the direction of
rotation of D.C. motor ? Fleming's left-hand rule [other wrong options] [Discuss in forum] Lenz's law Faraday's law Coloumb's law |
Q27 ⇒ Which D.C. motor will be suitable
alongwith flywheel for intermittent
light and heavy loads? Cumulatively compounded motor [other wrong options] [Discuss in forum] Series motor Shunt motor Differentially compounded motor |
Q28 ⇒ As compared to an induction motor, the
air gap in a D.C. motor is more [other wrong options] [Discuss in forum] less than 50% between 50% and 90% same |
Q29 ⇒ Three point starter can be used for both shunt and compound motor [other wrong options] [Discuss in forum] series motor only shunt motor only compound motor only |
Q30 ⇒ The armature torque of the D.C. shunt
motor is proportional to armature current only [other wrong options] [Discuss in forum] field flux only both (a) and (b) none of the above |
Q31 ⇒ 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 [other wrong options] [Discuss in forum] reduce to one-fourth value increase four folds be doubled |
Q32 ⇒ If the terminals of armature of D.C.
motor are interchanged, this action will
offer following kind of braking plugging [other wrong options] [Discuss in forum] regenerative dynamic braking none of the above any of the above |
Q33 ⇒ For constant torque drive which speed
control method is preferred ? Armature voltage control [other wrong options] [Discuss in forum] Field control Shunt armature control Mechanical loading system |
Q34 ⇒ In a D.C. generator all of the following
could be the effects of iron losses except Increase in terminal voltage [other wrong options] [Discuss in forum] Loss of efficiency Excessive heating of core Rise in temperature of ventilating air |
Q35 ⇒ Four point starter in the D.C. motor is
used not to effect the current passing through Hold on coil even if any change M the field current takes place [other wrong options] [Discuss in forum] to decrease the field current to increase the field current all of the above none of the above |
Q36 ⇒ Which loss in a D.C. generator varies
with load ? Copper loss [other wrong options] [Discuss in forum] Eddy current loss Hysteresis loss Windage loss |
Q37 ⇒ The purpose of retardation test on D.C.
shunt machines is to find out stray losses [other wrong options] [Discuss in forum] eddy current losses field copper losses windage losses |
Q38 ⇒ Where D.C. motor of H.P. 12 or more
requires frequent starting, stopping,
reversing and speed control drum type controller is used [other wrong options] [Discuss in forum] three point starter is used four point starter is used all above can be used |
Q39 ⇒ What will happen if supply terminals
of D.C. shunt motor are interchanged ? Motor will run at its normal speed in the same direction as it was running [other wrong options] [Discuss in forum] The direction of rotation will
reverse Motor will stop Motor will run at speed lower than the normal speed in the same direction |
Q40 ⇒ In a D.C. motor, the ratio Eb/Va indicates efficiency of the motor [other wrong options] [Discuss in forum] running torque of the motor starting torque of the motor speed regulation of the motor |
Or |