An 11 kV, three-phase, star-connected alternator has a synchronous impedance of 10∟80° Ω/phase and operates at unity power factor on infinite bus bars. It supplies a current of 300 A by using a general load diagram. Determine: (a) the full-load current for normal excitation ( motor mode) (b) the current and power factor for 100% excitation on 25% overload (generator mode) (c) the maximum power that the machine can develop in the generator mode for 50% excitation

An 11 kV, three-phase, star-connected alternator has a synchronous impedance of 10∟80° Ω/phase and operates at unity power factor on infinite bus bars. It supplies a current of 300 A by using a general load diagram. Determine: (a) the full-load current for normal excitation ( motor mode) (b) the current and power factor for 100% excitation on 25% overload (generator mode) (c) the maximum power that the machine can develop in the generator mode for 50% excitation

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter2: Fundamentals

Section: Chapter Questions

Problem 2.16P: A single-phase, 120V(rms),60Hz source supplies power to a series R-L circuit consisting of R=10 and...

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Concept explainers

Synchronous Motor

The synchronous motor is an AC electric type motor where at a steady-state the shaft rotation is synchronized with the supply current variable-frequency. To an integral number of AC cycles, the rotation period is exactly equal. The stator of the motor in the synchronous motor contains multi-phase AC electromagnets due to which a magnetic field is created that rotates in time with the oscillation of the line current. The rotor contains a permanent magnet and the rotor rotates in synchronization with the stator field at the same rate and provides the second synchronized magnetic field which is rotating in nature as a result. When the synchronous motor is supplied with independently excited multi-phase AC electromagnets on both the rotor and the stator, it is termed as a doubly-fed machine. The most widely used AC-type motors are the synchronous AC motor and the induction AC motors.

Question

An 11 kV, three-phase, star-connected alternator has a synchronous impedance of
10∟80° Ω/phase and operates at unity power factor on infinite bus bars. It supplies a
current of 300 A by using a general load diagram. Determine:
(a) the full-load current for normal excitation ( motor mode)
(b) the current and power factor for 100% excitation on 25% overload (generator mode)
(c) the maximum power that the machine can develop in the generator mode for 50% excitation

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Step 3: the maximum power that the machine can develop in the generator mode for 50% excitation

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