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Electrical Engineering Objective Questions { DC Motors }



99. Difference between the no load and full load speeds of a de shunt motor is of the order of
A.1%
B.5%
C.10%
D.20%

100. In a dc motor, the effect of flux due to armature reaction on the main flux is to make
A. unequal flux density distribution across both sections
B. flux direction deviate from radial in the air gap
C. both (a) and (b) above
D. none of these

101. Two dc series motors connected in series draw current 1 from supply and run at speed N. When the sae two motors are connected in parallel taking current I from the supply, the speed of each motor will be
A.N
B. 2N
C.4N
D.N/2

102. The torque-speed characteristic of a series motor is
A. parabola
B. rectangular hyperbola
C. linearly rising
D. linearly declining

103. The starter for a dc motor also provides protection to the motor against damage
A. due to short circuit in the equipment
B. from long term overload
C. from excessive starting currents
D. all of these

104. Starting resistor connected in
A. series with the field winding
B. parallel with the field winding
C. parallel with the armature
D. series with the armature in a dc motor

105. Direct online starters are not suitable for starting large dc motors because
A. the starting torque becomes very low
B. large voltage drop may occur in the supply mains
C. the moto may not start
D. the motor may run away

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