. Electric traction and transmission engineering . Fig. 36. £n = the electromotive force corresponding to the cur-rent /max as determined from the saturationcurve. Fig. 37,Ejnm = the electromotive force corresponding to the cur-rent /mil, Fig. 37,and for convenience let ■*-min and K = -mm At the instant when the arm touches stud i, the resist-ance ri should be such that the current flowing throughthe motor will not exceed /max; then RAILWAY MOTOR CONTROL. 8i / ^ (l) ■™« ~ „ 1 D whence the total resistance of the rheostat is. Fig. 37. (2) As the motor starts from rest and accelerates, the curre
. Electric traction and transmission engineering . Fig. 36. £n = the electromotive force corresponding to the cur-rent /max as determined from the saturationcurve. Fig. 37,Ejnm = the electromotive force corresponding to the cur-rent /mil, Fig. 37,and for convenience let ■*-min and K = -mm At the instant when the arm touches stud i, the resist-ance ri should be such that the current flowing throughthe motor will not exceed /max; then RAILWAY MOTOR CONTROL. 8i / ^ (l) ■™« ~ „ 1 D whence the total resistance of the rheostat is. Fig. 37. (2) As the motor starts from rest and accelerates, the currentgradually decreases, and at the instant when it reaches thevalue 7min the arm should leave stud i; then £-£, ■min . J-, Dividing (3) by (i) there results £-£1 (3) K = E which when solved for £1 gives 82 TRACTION AND TRANSMISSION. E^=E{l-K). (4) At the instant when the arm touches stud 2 the motorcurrent should again be /max, which is now equal to J _ E — E2 /A -•^^-r. + Rj ^^^ r. = ^-R^-^- (6) i max -^ max whence Since E2 and £1 are generated at the same speed andwith the respective field currents /max and /min, referenceto the saturation curve shows that E2 _ -Emax _•El -Emin and therefore E2 = qEi, which, by substitution from (4), becomes E2 = Eq{i-K). (7) At the instant when the current has again decreased to /min the arm leaves stud 2 and /min = , ^ (8) Dividing (8) by (5), ^ ^ E — E2 ^E — £2from which £2 = E{z-K)+ KEi, whence by substitution from (7) £2 = £ (i - ii:) + EqK (i - K). (9) Pr
Size: 1304px × 1916px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, bookpublisheretcetc, bookyear192
