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

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 leading the current flow will be Ia - Il -T - r. ZL t - 247 A 73 VT PF 73 2300 V so IA - A . The internal generated voltage at PF leading ignoring copper losses is EA - V - RAI a - jxS IA A y A A S A EA - 1328Z0 V - j Q a Ea - V Therefore the maximum torque at a power factor of 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 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 A IA fl P 373 kW 73 VT PF 73 2300 V - A IA fl P 788 kW 73 VT PF 73 2300 V -198 A The corresponding internal generated voltages at unity power factor are E A - Vy - jXS1A EA nl - 1328Z0 V- j Q A - V EAiMf - 1328Z0 V - j Q a - 1354Z V EA full - 1328Z0 V - j Q 198Z0 A - 1439Z- 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 M-file create a plot of armature current versus field current for the synchronous motor of Problem 6-4 at no-load .