Electrical Machine Design; The Design and Specification of Direct and Alternating Current Machinery Paperback - 5201

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1913 Excerpt: ...= 3450 ampere-turns. f AT mm = the maximum excitation =3X3450 = 10,400 ampere-turns, approximately. r, 2400. E--the voltage per phase =-_., since the connection is 1' fa = the flux per pole 1.73 = 1380 1380X108 2.22 X 0.96 X 72 X 12 X 60 3 = 3.8X10" If = the leakage factor, is assumed to be = 1.2. 3.8X10"X1.2 Plearea--9W = 48 sq. in. Lp = the axial length of the pole, is made 0.5 in. shorter than the frame length and =11.75 in. 117.1. 1 ' 48 S1' H P = the pole waist "0795x11.75 = 4.25 in. df. the depth of the field coil =0.75 in. from the table on page 240. MT = the mean turn =2(11.75 + 4.25) +-X 1.25 = 36 in. External periphery of field coil =38 in..... 10.400X36 M, the section of field wire = = 37,500 circular mils = 0.03 sq. in. = 0.04 X 0.75 (strip copper wound on edge) Watts per square inch for 65 C. rise =6.3 from Fig. 177, page 239. sf the spacc ffictor------0.04 + thickness of insulation = 0.8 using paper which is 0.01 in. thick ' 36: 6.3 X 0.75 X 0.8 X 1.27 = 4.75 in. 4 75 Tr, the number of turns per pole = " " 0.05 = 95 turns. The maximum exciting current =' raz--10,400 95 = 110 amperes Maximum output from exciter =120x110 = 13 kw. = 3.25 per cent. of the volt ampere rating. AT'g, the gap ampere-turns per pole at normal voltage and no-load, --ATmax--1.5X armature AT. per pole, approximately = 10,400-1.5x3450 = 5200 ampere-turns. ip, the pole enclosure, is taken as 0.65 which is an average value; if the pole arc be made too large, the pole leakage becomes excessive and the leakage factor high. Bg, the apparent gap density "josisxtz = 42,500 lines per square inch. _5200 X 3.2 "X C 42500 = 0.39 in. C = the Carter coefficient =1.12 from Fig. 40, page 44 3 = the air gap in inches =0.35 Calculation of the leakage fact...