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Review Problem 1. In a balanced 3-phase voltage generator, the different phase voltages are__degrees apart. c. 60 d. 30 a. 120 b. 240 2. In a balanced 3 phase wye connected system, the line voltage and the corresponding phase voltage are displaced from each other by а. О c. 30 d.120 b. 90 3. The phase sequence of a three phase system is BCA. The other possible phase sequences can be а. СВА с. САВ d. BAC b. АСB

Review Problem 1. In a balanced 3-phase voltage generator, the different phase voltages are__degrees apart. c. 60 d. 30 a. 120 b. 240 2. In a balanced 3 phase wye connected system, the line voltage and the corresponding phase voltage are displaced from each other by а. О c. 30 d.120 b. 90 3. The phase sequence of a three phase system is BCA. The other possible phase sequences can be а. СВА с. САВ d. BAC b. АСB

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. 32.506 KVAR b. 35.866 KVAR c. 40.391 KVAR d. 28.266 KVAR 15. A factory draws a lagging load of 2000 kW at a pf of 60% from a 6 kV bus line. A synchronous capacitor is installed to raise the power factor to unity. Assuming the synchronous capacitor losses are 275 kW, calculate the operating pf of the synchronous capacitor. c. 0.302 lead d. 0.113 lead a. 0.201 lead b. 0.103 lead 16. A SM is drawing 60 kW is connected in parallel with a load drawing a 250 kW at a power factor of 0.8 lagging. If the combined load has a power factor of 0.9 lagging, at what pf is SM operating? a. 0.862 lead c. 0.868 lead d. 0.874 lead b. 0.849 lead 17. Given the following voltages and load impedances. Vab = 220 cis 0 V Vbc = 220 cis 240 v Zbc = 10 cis O ohm Va = 220 cis 120 V Za = 10 cis 45 ohm Determine the reading of a kW meter connected with its current coil connected in the line "b" while the potential coil connected across lines "b" and "c" a. 5.45 kW Z = 10 cis 36.87 ohm c. 4.08 kW b. 5.12 kW d. 4.26 kW 18. A balanced three-phase loads draws 20 kW at 0.447 pf. Lagging from a 230 v, 60 Hz, three-phase transmission lines. Find the reading of the two wattmeter s properly connected to measure power c. 14.25 kW, 5.75 kW, d. 25.75 kW, -5.75 kW a. 18.45 kW, 1.55 kW b. 21.55 kW, -1.55 kW 19. Two watt-meter method is applied to a 3-phase motor running at full-load. The two wattmeter indicate 85.5 kW and 34.7 kW. What is the operating p.f. of the motor? a. 87.45% b. 89.49% c. 80.69% d. 94.76% 20. A 3-phase feeder carries two lagging balance loads. The power observed by each is measured by two wattmeter method, giving the following reading 1* load: W, = 160 kW W2 = 96 kW 2nd load: W, = 90 kW W2 = 48 kW What is the combined kVA load on the feeder? a. 434.68 b. 504.24 c. 462.35 d. 420.12
Transcribed Image Text:a. 32.506 KVAR b. 35.866 KVAR c. 40.391 KVAR d. 28.266 KVAR 15. A factory draws a lagging load of 2000 kW at a pf of 60% from a 6 kV bus line. A synchronous capacitor is installed to raise the power factor to unity. Assuming the synchronous capacitor losses are 275 kW, calculate the operating pf of the synchronous capacitor. c. 0.302 lead d. 0.113 lead a. 0.201 lead b. 0.103 lead 16. A SM is drawing 60 kW is connected in parallel with a load drawing a 250 kW at a power factor of 0.8 lagging. If the combined load has a power factor of 0.9 lagging, at what pf is SM operating? a. 0.862 lead c. 0.868 lead d. 0.874 lead b. 0.849 lead 17. Given the following voltages and load impedances. Vab = 220 cis 0 V Vbc = 220 cis 240 v Zbc = 10 cis O ohm Va = 220 cis 120 V Za = 10 cis 45 ohm Determine the reading of a kW meter connected with its current coil connected in the line "b" while the potential coil connected across lines "b" and "c" a. 5.45 kW Z = 10 cis 36.87 ohm c. 4.08 kW b. 5.12 kW d. 4.26 kW 18. A balanced three-phase loads draws 20 kW at 0.447 pf. Lagging from a 230 v, 60 Hz, three-phase transmission lines. Find the reading of the two wattmeter s properly connected to measure power c. 14.25 kW, 5.75 kW, d. 25.75 kW, -5.75 kW a. 18.45 kW, 1.55 kW b. 21.55 kW, -1.55 kW 19. Two watt-meter method is applied to a 3-phase motor running at full-load. The two wattmeter indicate 85.5 kW and 34.7 kW. What is the operating p.f. of the motor? a. 87.45% b. 89.49% c. 80.69% d. 94.76% 20. A 3-phase feeder carries two lagging balance loads. The power observed by each is measured by two wattmeter method, giving the following reading 1* load: W, = 160 kW W2 = 96 kW 2nd load: W, = 90 kW W2 = 48 kW What is the combined kVA load on the feeder? a. 434.68 b. 504.24 c. 462.35 d. 420.12
Universal College of Parañaque College of Engineering Electrical Engineering Department Drill Problem Polyphase Circuit Review Problem 1. In a balanced 3-phase voltage generator, the different phase voltages are_degrees apart. c. 60 d. 30 а. 120 b. 240 In a balanced 3 phase wye connected system, the line voltage and the corresponding phase voltage are displaced from each other by a. 0 b. 90 2. c. 30 d.120 The phase sequence of a three phase system is BCA. The other possible phase sequences can be 3. а. СВА b. АСВ c. CAB d. BAC In the balanced three-phase ABC system, the line voltage the phase current by 30 degrees. c. leads, leads d. leads, lags 5. Find the line voltage VaB if Ven = 265.6cis37 and phase sequence is BCA. c. 460cis-173 d. 460cis-53 4. the phase voltage and the line current a. lags, lags b. lags, leads a. 460cis-203 b. 460cis-83 6. Three 10 ohm resistors connected in wye are supplied from balanced three phase source where phase a line voltage is given by 230sin377t. What is the phase a line current? a. 13.28sin377t b. 23sin(377t-30) 7. A balanced delta connected load of 4 + j3 ohms per phase is connected to a 3-phase 230V supply. What is the line current? c. 13.28sin(377t-30) d. 40sin(377t+30) c. 23 A d. 33 A а. 80 A b. 46 A 8. A balanced delta load draws 10 Amps line current and 3Kw at 220V. The reactance of each phase of the load in ohms is а. 30 b. 23.5 9. A 170 KV, 3-phase electric source delivers 200MVA to a balanced load which has a power factor of 90% lagging. What is the line current? с. 38.1 d. 20 c. 402 A d. 679 A а. 257 A b. 502 A 10. A system consist of three equal resistors connected in wye and is fed from balanced three phase supply. How much power is reduced if one of the resistors is disconnected? а. 33% b. 25% c. 50% d. 15% 11. The resistance between any two terminals of a balanced delta connected load is 12 ohms. The resistance of each phase is а. 12 b. 4 12. A certain load takes 300 kW at 400 V. A three phase capacitor bank rated 15 kVA per phase is connected c. 18 d. 36 parallel with the load to raise the power factor of the system to 90% lagging. What is the power factor of the load before correction? c. 92% a. 99% b. 95% 13. A 132 kV line three phase system delivers 70.7 MVA on a balanced delta connected load of a power factor 70.7% lagging. Determine the reactance necessary to attain unity power factor. a. 1 092 ohms d. 88% c. 1142 ohms d. 1 045 ohms b. 965 ohms 14. A 150 kVA transformer bank will serve a load expected to draw 135 kW at 0.80 lagging power factor. Solve for the size of the capacitor bank needed to be added in order to prevent overloading of the transformer bank.
Transcribed Image Text:Universal College of Parañaque College of Engineering Electrical Engineering Department Drill Problem Polyphase Circuit Review Problem 1. In a balanced 3-phase voltage generator, the different phase voltages are_degrees apart. c. 60 d. 30 а. 120 b. 240 In a balanced 3 phase wye connected system, the line voltage and the corresponding phase voltage are displaced from each other by a. 0 b. 90 2. c. 30 d.120 The phase sequence of a three phase system is BCA. The other possible phase sequences can be 3. а. СВА b. АСВ c. CAB d. BAC In the balanced three-phase ABC system, the line voltage the phase current by 30 degrees. c. leads, leads d. leads, lags 5. Find the line voltage VaB if Ven = 265.6cis37 and phase sequence is BCA. c. 460cis-173 d. 460cis-53 4. the phase voltage and the line current a. lags, lags b. lags, leads a. 460cis-203 b. 460cis-83 6. Three 10 ohm resistors connected in wye are supplied from balanced three phase source where phase a line voltage is given by 230sin377t. What is the phase a line current? a. 13.28sin377t b. 23sin(377t-30) 7. A balanced delta connected load of 4 + j3 ohms per phase is connected to a 3-phase 230V supply. What is the line current? c. 13.28sin(377t-30) d. 40sin(377t+30) c. 23 A d. 33 A а. 80 A b. 46 A 8. A balanced delta load draws 10 Amps line current and 3Kw at 220V. The reactance of each phase of the load in ohms is а. 30 b. 23.5 9. A 170 KV, 3-phase electric source delivers 200MVA to a balanced load which has a power factor of 90% lagging. What is the line current? с. 38.1 d. 20 c. 402 A d. 679 A а. 257 A b. 502 A 10. A system consist of three equal resistors connected in wye and is fed from balanced three phase supply. How much power is reduced if one of the resistors is disconnected? а. 33% b. 25% c. 50% d. 15% 11. The resistance between any two terminals of a balanced delta connected load is 12 ohms. The resistance of each phase is а. 12 b. 4 12. A certain load takes 300 kW at 400 V. A three phase capacitor bank rated 15 kVA per phase is connected c. 18 d. 36 parallel with the load to raise the power factor of the system to 90% lagging. What is the power factor of the load before correction? c. 92% a. 99% b. 95% 13. A 132 kV line three phase system delivers 70.7 MVA on a balanced delta connected load of a power factor 70.7% lagging. Determine the reactance necessary to attain unity power factor. a. 1 092 ohms d. 88% c. 1142 ohms d. 1 045 ohms b. 965 ohms 14. A 150 kVA transformer bank will serve a load expected to draw 135 kW at 0.80 lagging power factor. Solve for the size of the capacitor bank needed to be added in order to prevent overloading of the transformer bank.
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