176.  Principal drawback of a servo motor is that it
A. has low reliability
B. has low starting torque
C. develops commutation problem
D. can handle only light loads

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177.  Servo?motors are small in comparison with ordinary motors because in servomotors
A. both torque and inertia are proportional to motor diameter
B. torque is proportional to square of motor diameter whereas inertia is proportional to diameter
C. both torque and inertia are proportional to square of motor diameter
D. small size is needed

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178. The servo?motor differs from ordinary motor in that it has
A. low inertia and high torque
B. high inertia and high torque
C. low inertia and low torque
D. high inertia and low torque

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179.  Which of the following device may be used to control the position of a very small load?
A. an AC servo-motor
B. a DC servo-motor
C. a synchro
D. none of these

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180.  Which of the following nonlinearity is caused by a servomotor?
A. Coulomb friction
B. saturation
C. dead-space
D. none of these

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181.  The reference phase and control phase in AC servo-motor are
A. always 90? out of phase
B. always in phase
C. always 1200 out of phase
D. always 180? out of phase

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182.  The starting torque of a servo?motor under unbalanced operation is proportional to
A. E
B. E2
C. E3
D. 1/E2

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