. The Bell System technical journal . relations applying to operation rciiiy beobtained from their graphical representation in Figs. 3 and 4. In thesetwo figures the path followed by the \ariables in dyamic operation isindicated by the dotted lines, with the dots spaced to indicate equaltime intervals between them. Fig. 3 shows the ip versus 3^ relation, referredto the steady state magnetization curves for various values of x, = 0 corresponding to the operated position, and x = Xi to the initialunoperated position. Fig. 4 shows the F \^ersus x relation, to-gether with the load
. The Bell System technical journal . relations applying to operation rciiiy beobtained from their graphical representation in Figs. 3 and 4. In thesetwo figures the path followed by the \ariables in dyamic operation isindicated by the dotted lines, with the dots spaced to indicate equaltime intervals between them. Fig. 3 shows the ip versus 3^ relation, referredto the steady state magnetization curves for various values of x, = 0 corresponding to the operated position, and x = Xi to the initialunoperated position. Fig. 4 shows the F \^ersus x relation, to-gether with the load curve (bounding the cross hatched area Y) and thesteady state pull curve for the applied mmf iFs . The flux and pull increase together with the armature at rest at .Viuntil the pull equals the back tension at the point 1. In the earlier mo-tion, 1-2, the velocity is small, and the reluctance (from (4)) changesslowly with x so the motion has little effect on the rate of flux develop- 118 THE BELL SYSTEM TECHNICAL JOIRXAL, JAXIAHY 1054. MAGNETOMOTIVE FORCE, J —i Fig. 3 — Field energy relations in the operation of an electromagnet. ment. In the later motion, 2-3, the reluctance changes more rapidlywith X, and the velocity is high, increasing d<p/dt so as to result in atemporary decrease in J. Operation is complete at 3, with (p and F stillbelow their steady state values at 4, which they then approach exponen-tially with .r = 0 . The mechanical work done in operation is represented in Fig. 4 bythe area under the dynamic pull curve (dotted line), and in Fig. 3 bythe area bounded by 0-1-2-3-0. This, of course, is less than the workthat would be done if -J were equal to its steady state value Js throughoutthe motion, represented by the area under the JFs curve in Fig. 4, andby the loop 0-3-4-5-0 in Fig. 3. In Fig. 4 it can be seen that the work doneexceeds the static load V by an amount represented by the shaded areaT, corresponding to the kinetic energy of the armature and the
Size: 1546px × 1617px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
