Design of a 20,000 . esurface of the iron when the watts lost per unitvolume are considerable. The design is proceeded on the basis of 14,000 gausses as an upper limit for the flux densi-ty. If no oil ducts are provided, between sectionsof the stampings, the sta&king factor will beabout A gross length of 46 inches (Item 35)gives 41 inches for the net length and a gitdsssection of 41 x 20 = 820 square inches. WhenceB = X 107 / X Q20 = 13,920; and thetotal weight of iron is 820 x 206 x = 46,300pounds. The watts per pound from curve Fig. 3are w = ; there
Design of a 20,000 . esurface of the iron when the watts lost per unitvolume are considerable. The design is proceeded on the basis of 14,000 gausses as an upper limit for the flux densi-ty. If no oil ducts are provided, between sectionsof the stampings, the sta&king factor will beabout A gross length of 46 inches (Item 35)gives 41 inches for the net length and a gitdsssection of 41 x 20 = 820 square inches. WhenceB = X 107 / X Q20 = 13,920; and thetotal weight of iron is 820 x 206 x = 46,300pounds. The watts per pound from curve Fig. 3are w = ; therefore Wj_ = 1 .78 x 46,300 =82,400 watts. Items (42) to (49). Copper losses. The meanlength per turn of the windings is best obtainedfrom Fig. 4. This sketch shows a section throughthe stampings parallel with the plane of the mean length per turn of the secondary as meas-ured off the drawing is 236 inches and since thelength per turn of the primary coils will be aboutthe same, this dimension will be used in both cases 36. ^^<^. -f. Taking the resistivity of the copper at x 10~^ohms per inch jube, the primary resistance (hot) is R, = X 236 X 560 / 10^ x = ohms. p 2 Whence the losses (Item 44) are Ip x R^ = X = 41,150 watts. For the secondary wind-ing we have R2 = ^9 x 2^6 x 56 / 10^ x =.1245 ohm; whence the losses (Item 47) are I^ xR2 = 1616^ X .1245 = 41,150 watts. W^ = 41,l5o-*- 41,150 = 82,300 watts, which is appreciablyless than the permissible copper loss. The v/eight of copper (Item 49) is(236 x 56OX -^ 236 x 56 x ) x = 8,100pounds. Items (50) to (51). Efficiency. The fullload efficiency on unity power factor is 20,000,000 / 20,000,000 4 82,300 i- 82,400 = full load efficiency on 80 per cent powerfactor is 20,000,000 x / 20,000,000 x •+ 164,700 =.939. Item (52). Open circuit exciting curve of Fig. 5, we obtain for a densityof B = 13,900, the value of per pound ofcor
Size: 2171px × 1151px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookiddesignof2000, bookyear1920
