Q28 Q33 Refer To The No Load Excitation Curve Of The Labvolt Sg Shown Below No Load Excitation Curve 1800rpm Eo Ln 1 (51.26 KiB) Viewed 16 times
Q28 - Q33 refer to the no-load excitation curve of the labVolt SG shown below. No-load excitation curve @ 1800rpm Eo(LN) 160 140 120 100 80 60 40 20 ΤΑ 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 DC Excitation current (A) The figure above shows the no-load excitation curve of the LabVolt 3-ph, 4-pole, 60Hz, 208V, wye-connected, 120VA synchronous generator at rated speed of 1800rpm. The generator has negligible stator resistance and synchronous reactance of 100 2/phase. The rotor winding has resistance of 150 £2 and is connected in series with a 0-500 £2 field (excitation) control rheostat. Answer the following questions relating to the LabVolt Synchronous Generator. Q28. The DC excitation current required for a no-load voltage of 208VLL at 60 Hz is: A. B. C. D. E. 0.8 A 0.6 A 0.4 A 0.2 A
Q29. The no-load terminal voltage (line-line) for a DC excitation current of 0.55A and shaft speed of 1875 rpm is: 252.6 V 242.5 V 232.8 V 216.7 V 208 V A. B. C. D. E. Q30. The DC excitation current required to generate a no-load voltage (line-line) of 250V at 66 Hz is: A. B. C. D. E. Q31. What is the minimum value of no-load terminal voltage (LL) at rated speed that can be obtained if the rotor winding is energized from a fixed 130V de supply? OV A. B. C. D. E. A. B. C. 0.94 A 0.83 A 0.65 A 0.47 A 0.29 A D. E. Q32. What is the maximum value of no-load terminal voltage (LL) at rated speed that can be obtained if the rotor winding is energized from a fixed 130V de supply? 277 V 272 V 70 V 121 V A. B. C. D. E. 147 V 157 V 240 V 160 V 157 V Q33. What is the value of line-neutral excitation voltage is needed to maintain rated terminal voltage at rated speed when the load is a 400 2/ph capacitor bank? 208 V 150 V 123.7 V 120 V 90 V
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