tailieunhanh - Problem solutions: Chapter 7

tài liệu Problem solutions: Chapter 7 sau đây. Tài liệu dành cho các bạn học chuyên ngành Điện. Tham khảo nội dung tài liệu để nắm bắt nội dung chi tiết. | 85 PROBLEM SOLUTIONS Chapter 7 Problem part a wm x Va. part b wm x If part c wm will be constant. Problem part a For constant terminal voltage the product nIf where n is the motor speed is constant. Hence since If x 1 Rf Rỉ Rf 5 1180 1250 and hence Rf Q. part b 1380 r min Problem Check this part a wm halved Ia constant part b wm halved Ia doubled part c wm halved Ia halved part d wm constant Ia doubled part e wm halved Ia reduced by a factor of 4. Problem part a Rated armature current 25 kW 250-V 100 A. part b At 1200 r min Ea can be determined directly from the magnetization curve of Fig. . The armature voltage can be calculated as Va Ea Ia Ra and the power output as Pout VaIa. With Ia 100 A If A Ea V Va V Pout kW 150 164 240 254 270 284 part c The solution proceeds as in part b but with the generated voltage equal to 900 1200 times that of part b If A Ea V Va V Pout kW 112 126 180 194 202 216 Problem part a Mil Power kW 87 Problem part a Pshaft Ea Va - Ea Ra and thus Ea Va wVa2 - 4PshaftRa 2 The motor speed n can then be found from n 1200 f Ea X 1200 r min Here is the desired plot produced by MATLAB part b The solution for Ea proceeds as in part a . With the speed constant at 1200 r min and hence constant wm solve for If as If K where Kf 150D V A. Here is the desired plot produced by .