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In analyzing a hydropower site, it is found guibe that the turbines should turn at close to 350 r/min. If the directly coupled genera- 3 no tors must generate a frequency of 60 Hz, calculate the following: a. The number of poles on the rotor b. The exact turbine speed An isolated 3-phase generator produces a 4

In analyzing a hydropower site, it is found guibe that the turbines should turn at close to 350 r/min. If the directly coupled genera- 3 no tors must generate a frequency of 60 Hz, calculate the following: a. The number of poles on the rotor b. The exact turbine speed An isolated 3-phase generator produces a 4

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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9 In 8, if the is kept constant, the and c. load sdi tndr bae ad b. load basotb a. Resistive Tol equivalent of a and ex- tance of a 3-phase Draw the plain the of all the parameters. terminals? W ama orli oale SYNCHRONOUS SYNCHRONOUS GENERATORS ed only 27 times. Consequently, the effi- nachine was bound to increase with size. nal machine produced an output of e larger machine has a mass of 540 kg s 81 kW. Consequently, it produces = 150 W/kg which is 3 times machines is a very important matter. frequency if the speed is a. 1000 r/min b. 5 r/min Intermediate level What is meant by the synchronous reac- of a 3-phase generator? Draw the %3D before. Questions and Problems er generator is therefore relatively cheaper than the smaller machine. As hty-one 1 kW generators were used to kW, their combiìned mass would be 01 Practical level What are the advantages of using a stationary 1. plain the meaning of all the parameters. armature in large synchronous generators? Why is the stator always connected in wye? 2. State the main differences between steam. 1620 kg. This generating center would me more costly and take up more floor he single 81 kW generator. 1Ovil mer matter of interest, the moment of in- rotor is proportional to its mass and the s radius. Hence, when linear dimensions J will increase by a factor of J = mr² = 3 = 243. The moment of inertia of nachine is therefore 243-0.0075 kgm² = II turbine generators and salient-pole genera- tors. For a given power output, which of these machines is the larger? a schematic circuit diagram, show how the rotor in Fig. 7 is excited. Referring to Fig. 13, calculate the exciting 12 current needed to generate a no-load line voltage of lod a. 24.2 kV b. 12.1 kV A 3-phase generator possesses a synchro- nous reactance of 6 N and the excitation voltage E, is 3 kV per phase (ref. Fig. 19). Calculate the line-to-neutral voltage E for a resistive load of 8 N and draw the phasor diagram. a. In Problem 13, draw the curve of E versus I for the following resistive loads: infinity, 24, 12, 6, 3, 0 ohms. b. Calculate the active power P per phase in each case. 3. In analyzing a hydropower site, it is found that the turbines should turn at close to %3D %3D 350 r/min. If the directly coupled genera- %3D ILOU tors must generate a frequency of 60 Hz, 13 ristics of the larger generator are w. They are in striking contrast to W machine. calculate the following: a. The number of poles on the rotor b. The exact turbine speed 81 kW 1080 V, 3-phase 43.2 A An isolated 3-phase generator produces a 4. no-load line voltage of 13.2 kV. If a load pecs be of 14 having a lagging power factor of 0.8 is connected to the machine, must the excita- S c tion be increased or decreased in order to maintain the same line voltage? inertia ug po meter 5. C. Draw the curve of E versus P. For what value of load resistance is the output a maximum? smido ator can be connected to a 3-phase system? 9. Calculate the number of poles Wkg 15 power is temperature rise. When tripled, the heat-dissipating nachine increases 9 times but 27 times. Hence, the power dis- meter increases by a factor of 3. unless better cooling means are generator shown in Fig. 11. circumference of the stator. 8. the following loads are connected to Ts terminals? w ama a. Resistive load b. Inductive load o E, 32440 V has to be limited to a maximum of X, = 144 N %3D R=17 N umixam s Srb gatarabaiw s
Transcribed Image Text:9 In 8, if the is kept constant, the and c. load sdi tndr bae ad b. load basotb a. Resistive Tol equivalent of a and ex- tance of a 3-phase Draw the plain the of all the parameters. terminals? W ama orli oale SYNCHRONOUS SYNCHRONOUS GENERATORS ed only 27 times. Consequently, the effi- nachine was bound to increase with size. nal machine produced an output of e larger machine has a mass of 540 kg s 81 kW. Consequently, it produces = 150 W/kg which is 3 times machines is a very important matter. frequency if the speed is a. 1000 r/min b. 5 r/min Intermediate level What is meant by the synchronous reac- of a 3-phase generator? Draw the %3D before. Questions and Problems er generator is therefore relatively cheaper than the smaller machine. As hty-one 1 kW generators were used to kW, their combiìned mass would be 01 Practical level What are the advantages of using a stationary 1. plain the meaning of all the parameters. armature in large synchronous generators? Why is the stator always connected in wye? 2. State the main differences between steam. 1620 kg. This generating center would me more costly and take up more floor he single 81 kW generator. 1Ovil mer matter of interest, the moment of in- rotor is proportional to its mass and the s radius. Hence, when linear dimensions J will increase by a factor of J = mr² = 3 = 243. The moment of inertia of nachine is therefore 243-0.0075 kgm² = II turbine generators and salient-pole genera- tors. For a given power output, which of these machines is the larger? a schematic circuit diagram, show how the rotor in Fig. 7 is excited. Referring to Fig. 13, calculate the exciting 12 current needed to generate a no-load line voltage of lod a. 24.2 kV b. 12.1 kV A 3-phase generator possesses a synchro- nous reactance of 6 N and the excitation voltage E, is 3 kV per phase (ref. Fig. 19). Calculate the line-to-neutral voltage E for a resistive load of 8 N and draw the phasor diagram. a. In Problem 13, draw the curve of E versus I for the following resistive loads: infinity, 24, 12, 6, 3, 0 ohms. b. Calculate the active power P per phase in each case. 3. In analyzing a hydropower site, it is found that the turbines should turn at close to %3D %3D 350 r/min. If the directly coupled genera- %3D ILOU tors must generate a frequency of 60 Hz, 13 ristics of the larger generator are w. They are in striking contrast to W machine. calculate the following: a. The number of poles on the rotor b. The exact turbine speed 81 kW 1080 V, 3-phase 43.2 A An isolated 3-phase generator produces a 4. no-load line voltage of 13.2 kV. If a load pecs be of 14 having a lagging power factor of 0.8 is connected to the machine, must the excita- S c tion be increased or decreased in order to maintain the same line voltage? inertia ug po meter 5. C. Draw the curve of E versus P. For what value of load resistance is the output a maximum? smido ator can be connected to a 3-phase system? 9. Calculate the number of poles Wkg 15 power is temperature rise. When tripled, the heat-dissipating nachine increases 9 times but 27 times. Hence, the power dis- meter increases by a factor of 3. unless better cooling means are generator shown in Fig. 11. circumference of the stator. 8. the following loads are connected to Ts terminals? w ama a. Resistive load b. Inductive load o E, 32440 V has to be limited to a maximum of X, = 144 N %3D R=17 N umixam s Srb gatarabaiw s
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