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This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1920 edition. Excerpt: ...line in one of the laminations. The thickness of the laminations is assumed to be sufficiently small with respect to their width that the length of the current path can be represented by 2w; the cross-sectional area of the current path is tl/2. The resistance of the path is therefore r=4Kiw/tl, where Ki is the specific resistance of the iron. The total flux in one lamination is wtB, and the flux cut per second will be 4fwtB, since the flux wtB will be cut four times during each cycle. The effective e.m.f. will therefore be e = 4 K2fwtB, where K2 is a constant depending on the manner in which the flux varies with time. The value of the eddy current will be e/r = KzWfB/Ki, and the power loss per lamination will be Pr, or p=4(K22/K1)wll3PB2. (63) But wit is equal to v, the volume of the lamination, so that we can write (substituting K for A-K?2/Ki), p = Kvl2B2p. (64) The total loss will be pn, where n is the number of laminations; but vn is the total volume V of the core, so that the total loss is P = KVt2f2B2 (65) as stated above. This formula is useful as showing the general effect of the various factors on the eddy current loss, but it is not very reliable for actual calculations on account of the fact that certain other factors, such as incomplete insulation between laminations, variations in the flux distribution and its manner of change with time, make the proper selection of the constant K quite uncertain. In practice use is made of experimental curves secured from tests under the desired conditions, and showing total core loss (hysteresis and eddy current loss) per unit volume or weight. See Standard Handbook for Electrical Engineers, pp. 291-292. The usual thickness of laminations range from 14 to 28 mils and the net volume of iron...

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