Correspondence: Stray loss measurements [discussion of "Separation of Stray Losses in A-C, Generators" by M.C. Holmes

Abstract

The author of this correspondence wishes to add some further verification to conclusions of the above-named article by M.C. Holmes (A.I.E.E. Journal, March 1929, p. 224). The author states that he and a colleague have made several calorimeter tests on turbine generators and found that the load losses at the normal voltage, zero per cent power factor, overexcited condition were substantially the same as those measured on short-circuit. Recently they have made similar tests on some rather large machines at 80 per cent power factor and found the same conditions. In none of these machines was the pole face loss abnormally high, yet, if anything, the load loss at normal voltage was a little greater than that measured on short circuit. Also, they have made calculations to determine the axial depth of flux penetration in the armature iron near the ends of the machine, and obtained results comparable to those shown in Fig. 8 of Holmes' paper (see "Iron Losses in Turbine Generators," by C.M. Laffoon and J.F. Calvert, A.I.E.E. Quarterly TRANS., 48, Part 3, 1929).