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(McGraw-Hill) (Instructors Manual) Electric Machinery Fundamentals 4th Edition Episode 1 Part 9

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Tham khảo tài liệu '(mcgraw-hill) (instructors manual) electric machinery fundamentals 4th edition episode 1 part 9', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | If we are ignoring the resistance of the motor then the input power would be 788 kW note that copper losses are ignored . At a power factor of 0.8 leading the current flow will be Ia - Il -T - r. ZL t - 247 A 73 VT PF 73 2300 V 0.8 so IA - 247Z36.87 A . The internal generated voltage at 0.8 PF leading ignoring copper losses is EA - V - RAI a - jxS IA A y A A S A EA - 1328Z0 V - j 2.8 Q 247Z36.87 a Ea - 1829Z-17.6 V Therefore the maximum torque at a power factor of 0.8 leading is _ __ 3 V EA __3 1328 V 1829 V a XS 3600 r min 1mn n lal v 7 60s 1r --------- 6093 N m 2.8 6-4. Plot the V-curves IA versus IF for the synchronous motor of Problem 6-3 at no-load half-load and fullload conditions. Note that an electronic version of the open-circuit characteristics in Figure P6-1 is available at the book s Web site. It may simplify the calculations required by this problem. Also you may assume that RA is negligible for this calculation. Solution The input power at no-load half-load and full-load conditions is given below. Note that we are assuming that RA is negligible in each case. PIN nl - 24 kW 18 kW - 42 kW PIN half - 500 hp 746 W hp 24 kW 18 kW - 373 kW PIN full - 1000 hp 746 W hp 24 kW 18 kW - 788 kW If the power factor is adjusted to unity then armature currents will be IA nl P 42 kW 73 Vt PF 73 2300 V 1.0 -10.5 A IA fl P 373 kW 73 VT PF 73 2300 V 1.0 - 93.6 A IA fl P 788 kW 73 VT PF 73 2300 V 1.0 -198 A The corresponding internal generated voltages at unity power factor are E A - Vy - jXS1A EA nl - 1328Z0 V- j 2.8 Q 10.5Z0 A - 1328.3Z-1.27 V EAiMf - 1328Z0 V - j 1.5 Q 93.6Z0 a - 1354Z -11.2 V EA full - 1328Z0 V - j 2.8 Q 198Z0 A - 1439Z- 22.7 V These values of EA and 3 at unity power factor can serve as reference points in calculating the synchronous motor V-curves. The MATLAB program to solve this problem is shown below 155 M-file prob6_4.m M-file create a plot of armature current versus field current for the synchronous motor of Problem 6-4 at no-load .