. A text-book of electrical engineering;. ance, and the Ossanna circle, the former dotted and the latter as a fullline. The auxiliary circle through 0 is also drawn as a full Une. We sawin the previous section that the triangles OP A, QP^O were similar. If wedrop the ordinate PBK, the angle OPK is equal to ^. The triangles OBP,OP A and QP^O are therefore similar, arid we have PB Ii iiRi v^- The power lost in stator resistance is 3V-i?i = power supplied to the stator is Pr = , = 3V,.PK. * See , 1900, No. 52. 412 Electrical Engineering By subtracting one from the ot
. A text-book of electrical engineering;. ance, and the Ossanna circle, the former dotted and the latter as a fullline. The auxiliary circle through 0 is also drawn as a full Une. We sawin the previous section that the triangles OP A, QP^O were similar. If wedrop the ordinate PBK, the angle OPK is equal to ^. The triangles OBP,OP A and QP^O are therefore similar, arid we have PB Ii iiRi v^- The power lost in stator resistance is 3V-i?i = power supplied to the stator is Pr = , = 3V,.PK. * See , 1900, No. 52. 412 Electrical Engineering By subtracting one from the other we get the power transmitted to the The length F^P in Fig. 407 is a measure of the rotor current, in accord-ance with equation (181). To find F^P in Fig. 410 we must reduce FA in ,, ^. £, OPthe ratio ^ = ^, or , ^^^\^ =FiP=FA.^.(H-Ti)Zi ^ OA . To make this reduction a horizontal is drawn through B to meet FAin C. The ordinate through C cuts the original circle in D. Then we have FD^ FV FC OBFA^~ FH~ FA~OA A1 OB OB OP qp^ OA~OPOA~OA^. From these two equations, it follows that OP T 7FD = FA .^-^ = ^^^ The hue GJ is drawn at,an angle ^0 with the horizontal, where jSq is thesame as in equations (186) and (187) on page 403. Then we have FV tan;8o FD^._FD^_ I^.Z^ Iq From this equation, together with equation (186) on page 403, we get UV = iLjJhV, ■ The loss in the rotor is therefore and FV = < 128. Ossannas Circle-diagram 413 Since CV = BK, the mechanical power given out by the rotor must be P = , since the relative slip is equal to the relative loss in the rotor, f _VV LHA CV AH-For the convenient determination of the slip Hhe method of Fig. 405can be employed, using the point A in the original circle. 129. The most Convenient Form of the Circle-diagram. Ossannas method of correcting the circle-diagram, as described in theforegoing section, has the advantage of strict accuracy, but the decideddisadvantage of being extremely cumbersome. For this reason anothe
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