81.
Which of the following law/rule can he used to determine the direction of rotation of D.C. motor ?
A
Lenzs law
B
Faradays law
C
Coloumbs law
D
Flemings left-hand rule
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121 practice sets · Page 5 of 7
Which of the following law/rule can he used to determine the direction of rotation of D.C. motor ?
Lenzs law
Faradays law
Coloumbs law
Flemings left-hand rule
Which of the following application requires high starting torque ?
Lathe machine
Centrifugal pump
Locomotive
Air blower
Which motor should not be started on no-load ?
Series motor
Shunt motor
Cumulatively compounded motor
Differentially compounded motor.
Which motor has the poorest speed control?
Differentially compounded motor
Cumulatively compounded motor
Shunt motor
Series motor
Which method of braking is generally used in elevators ?
Plugging
Regenerative braking
Rheostatic braking
None of the above
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
Which D.C. motor will be preferred for machine tools ?
Series motor
Shunt motor
Cumulative compound motor
Differential compound motor
Which D.C. motor is preferred for elevators ?
Shunt motor
Series motor
Differential compound motor
Cumulative compound motor
Which D.C. motor is generally preferred for cranes and hoists ?
Series motor
Shunt motor
Cumulatively compounded motor
Differentially compounded motor
Which D.C. motor has got maximum self relieving property ?
Series motor
Shunt motor
Cumulatively compounded motor
Differentially compounded motor
Which D.C. motor has got maximum self loading property?
Series motor
Shunt motor
Cumulatively compounded motor
Differentially compounded motor
Where D.C. motor of H.P. 12 or more requires frequent starting, stopping, reversingand speed control
four point starter is used
all above can be used
drum type controller is used
three point starter is used
When two D.C. series motors are connected in parallel, the resultant speed is
normal speed
zero
more than the normal speed
loss than the normal speed
When the armature of a D.C. motor rotates, e.m.f. induced is
back e.m.f.
none of the above
self-induced e.m.f.
mutually induced e.m.f.
What will happen if the back e.m.f. of a D.C. motor vanishes suddenly?
The armature may burn
The motor will run noisy
The motor will stop
The motor will continue to run
Ward-Leonard control is basically a
field control method
armature resistance control method
voltage control method
field divertor method
Usually wide and sensitive speed control is desired in case of
steel rolling mills
colliery winders
centrifugal pumps
elevators
Torque developed by a D.C. motor depends upon
current flow through the conductors
all above factors
magnetic field
active length of the conductor
To get the speed of D.C, motor below the normal without wastage of electrical energy is used.
any of the above method
none of the above method
Ward Leonard control
rheostatic control
Three point starter can be used for
compound motor only
both shunt and compound motor
series motor only
shunt motor only