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Higher Study | Electrical Machines | Alternator and Synchronous Motors

When the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop
An over-excited synchronous motor takes
Under short circuit condition the power factor of synchronous machine is:
The load characteristic of alternator will have drooping shape due to
The necessary condition for parallel operation of two alternators is
During the operation of a connecting a busbar in parallel with an incoming alternator the:
Two identical alternators are running in parallel and carry equal loads. If the excitation of one alternator is increased without changing the steam supply then:
Usually, the number of poles in a turbo alternator is
An alternator is being synchronised to the power station bus bars whose frequency is 50 Hz. If the bulb of the synchroscope glows with maximum brightness, the frequency of the alternator is:
What happens when one phase of a synchronous motor is short circuited?
When a generator supplies a lagging load it means that the magnetic energy is supplied to the load and the net reactive power gets reduced in the generator. In this case, what effect will armature reaction have?
When excitation of synchronous motor is increased upto normal excitation from under excitation, armature current
When two alternators are running in parallel, if prime mover of one of the alternator is disconnect, that alternator will:
Consider the following statements with respect to synchronous machines. State whether these statements are true or false. (a) Armature reaction is demagnetising when a generating machine supplies zero power factor lagging current. (b) Armature reaction is magnetising when a generating machine supplies zero power factor leading current. (c) Armature reaction is mostly cross-magnetising, though it has a small demagnetising component, when a generating machine supplies unity power factor current.
Consider the following statements: 1. A synchronous motor has no starting torque but when started it always runs at a fixed speed. 2. A single-phase reluctance motor is not self-starting even if path for eddy currents are provided in the rotor 3. A single-phase hysteresis motor is self-starting Which of these statement(s) is/are correct?
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