field-discharge resistor
Synchronous Generator
In comparison to an asynchronous generator, it is a machine where the rotor speed is equal to the rotating magnetic field produced by the stator, i.e., mechanical speed is equal to the electrical speed, thus called synchronous, and not asynchronous.
Salient Pole Rotor
Salient pole rotor includes a large number of exposed poles mounted on a magnetic wheel. The construction of a bright pole is as shown in the image on the left. The proposed poles are made of metal laminations. The rotor winding is provided on these poles and is supported by pole shoes.
Y-1). A field-discharge resistor is installed in the rotor circuit of a 3-phase synchronous motor to....
a) vary the speed of the motor b) limit the current in the amortisseur winding c) protect the wire-wound armature windings from excessive current during starting and shut-down. d) none of the above
Y-2)._____________ is when a 3-phase synchronous motor has been overloaded to a point where it falls out of synchronism.
a) Pullout torque b) De-phasing c) Single phasing d) none of the above
Y-3). The power factor of a 3-phase synchronous motor can be varied by adjusting the_________
a) speed b) horsepower rating c) DC field excitation d) all of the above
Y-4) A 3-phase synchronous motor can have a leading power factor.
a) true b) false
Y-5). Given a constant field excitation, what is the effect on the power factor of a 3-phase synchronous motor with an increasing load?
a) the power factor stays the same b) the power factor improves c) the power factor gets poorer
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