Question is ⇒ Small D.C. motors up to 5 H.P. usually have, Options are ⇒ (A) 2 poles, (B) 4 poles, (C) 6 poles, (D) 8 poles, (E) , Leave your comments or Download question paper.

Question is ⇒ Small D.C. motors up to 5 H.P. usually have, Options are ⇒ (A) 2 poles, (B) 4 poles, (C) 6 poles, (D) 8 poles, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	Small D.C. motors up to 5 H.P. usually have
A.	2 poles [Correct Answer]
B.	4 poles [Wrong Answer]
C.	6 poles [Wrong Answer]
D.	8 poles [Wrong Answer]
View Answer 21 -21 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

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Also Read Similar Questions Below :

⇒ 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

⇒ The current drawn by the armature of D.C. motor is directly proportional to
the torque required
the speed of the motor
the voltage across the terminals
none of the above

⇒ Hopkinson's test is conducted at
no load
part load
low load
full load

⇒ 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

⇒ When the electric train is moving down a hill the D.C. motor act as
D.C. series generator
D.C. shunt generator
D.C. shunt motor
D.C. series motor

⇒ As compared to an induction motor, the air gap in a D.C. motor is
less than 50%
between 50% and 90%
same
more

⇒ 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

⇒ 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

⇒ 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 B_max is the maximum flux density, then eddy cu rrent loss will vary as
B_max
(B_max)²
(B_max)^1.2
(B_max)^2.4

⇒ Which motor should not be started on no-load ?
Series motor
Shunt motor
Cumulatively compounded motor
Differentially compounded motor

⇒ The speed of a D.C. motor, under constant load conditions, is affected by
back e.m.f.
field flux
armature current
none of the above

⇒ 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

⇒ Field winding of a D.C. series motor is usually provided with thick wire
to provide large flux
to reduce the use of insulating materials
as it carries large load current
in order to reduce eddy current

⇒ Which of the following motors is most suitable for signalling devices and many kinds of timers ?
D.C. shunt motor
D.C. series motor
Induction motor
Reluctance 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 speed regulation of a D.C. motor is

lowest speed

highest speed

highest speed - lowest speed

average speed

no-load speed - full-load speed

full-load speed

no-load speed - full-load speed

no-load 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}

⇒ A D.C. motor can be easily identified by
winding
commutator
size of conductor
yoke

⇒ 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

⇒ 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

⇒ Speed control by Ward Leonard method gives uniform speed variation
in one direction
in both directions
below normal speed only
above normal speed only

⇒ 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 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

⇒ 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

⇒ As there is no back e.m.f. at the instant of starting, a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit
a resistance is connected in series with armature
a resistance is connected parallel to the armature
armature is temporarily open circuited
a high value resistor is connected across the field winding

⇒ D.C. generators are normally designed for maximum efficiency around
full-load
rated r.p.m.
rated voltage
all of the above

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

⇒ A brake test on D.C. motors is usually restricted to
small horse power motors
variable speed motors
high speed motors
open frame type motors.

⇒ Three point starter can be used for
series motor only
shunt motor only
compound motor only
both shunt and compound motor