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A 30, 5 kVA, 208 V, four-pole, 60 Hz, star-connected synchronous machine has negligible Stator winding resistance and a synchronous reactance of 8 ohms per phase at rated terminal voltage. The machine is first operated as a generator in parallel with a 30, 208 V, 60 Hz power supply. (a) Determine the excitation voltage and the power angle when the machine is delivering rated kVA at 0.8 PF lagging. Draw the phasor diagram for this condition. (b) If the field excitation current is now increased by 20 percent (without changing the prime mover power), find the stator current, power factor, and reactive kVA supplied by the machine. (c) With the field current as in (a), the prime mover power is slowly increased. What is the steady-state (or static) stability limit? What are the corresponding values of the stator (or armature) current, power factor, and reactive power at this maximum power transfer condition?

A 30, 5 kVA, 208 V, four-pole, 60 Hz, star-connected synchronous machine has negligible Stator winding resistance and a synchronous reactance of 8 ohms per phase at rated terminal voltage. The machine is first operated as a generator in parallel with a 30, 208 V, 60 Hz power supply. (a) Determine the excitation voltage and the power angle when the machine is delivering rated kVA at 0.8 PF lagging. Draw the phasor diagram for this condition. (b) If the field excitation current is now increased by 20 percent (without changing the prime mover power), find the stator current, power factor, and reactive kVA supplied by the machine. (c) With the field current as in (a), the prime mover power is slowly increased. What is the steady-state (or static) stability limit? What are the corresponding values of the stator (or armature) current, power factor, and reactive power at this maximum power transfer condition?

Introductory Circuit Analysis (13th Edition)
Introductory Circuit Analysis (13th Edition)
13th Edition
ISBN:9780133923605
Author:Robert L. Boylestad
Publisher:Robert L. Boylestad
Chapter1: Introduction
Section: Chapter Questions
Problem 1P: Visit your local library (at school or home) and describe the extent to which it provides literature...
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A 30, 5 kVA, 208 V, four-pole, 60 Hz, star-connected synchronous machine has negligible Stator winding resistance and a synchronous reactance of 8 ohms per phase at rated terminal voltage. The machine is first operated as a generator in parallel with a 30, 208 V, 60 Hz power supply. (a) Determine the excitation voltage and the power angle when the machine is delivering rated kVA at 0.8 PF lagging. Draw the phasor diagram for this condition. (b) If the field excitation current is now increased by 20 percent (without changing the prime mover power), find the stator current, power factor, and reactive kVA supplied by the machine. (c) With the field current as in (a), the prime mover power is slowly increased. What is the steady-state (or static) stability limit? What are the corresponding values of the stator (or armature) current, power factor, and reactive power at this maximum power transfer condition?
Transcribed Image Text:A 30, 5 kVA, 208 V, four-pole, 60 Hz, star-connected synchronous machine has negligible Stator winding resistance and a synchronous reactance of 8 ohms per phase at rated terminal voltage. The machine is first operated as a generator in parallel with a 30, 208 V, 60 Hz power supply. (a) Determine the excitation voltage and the power angle when the machine is delivering rated kVA at 0.8 PF lagging. Draw the phasor diagram for this condition. (b) If the field excitation current is now increased by 20 percent (without changing the prime mover power), find the stator current, power factor, and reactive kVA supplied by the machine. (c) With the field current as in (a), the prime mover power is slowly increased. What is the steady-state (or static) stability limit? What are the corresponding values of the stator (or armature) current, power factor, and reactive power at this maximum power transfer condition?
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