402 MATTHEWS: THE THlffTYANlNTH KELVIN LECTURE

(6) ADRIAN, E. D., and ZOTTERMAN, Y.: Journal of Physiology,1926, pp. 151 and 465.

(7) HARTLINE, H. K.: Journal of Cellular and ComparativePhysiology, 1932, 1, p. 277.

(8) ARVANITAKI, A.: Journal of Neurophysiology, 1942, 5, p. 89.(9) MATTHEWS, B. H. C : Journal of Physiology, 71, p. 64.

(10) FESSARD, A.: "Proprietes Rythmiques de la MatiereVivante"(Hermann, Paris, 1936).

(11) BRINK, F., BRONK, D. W., and LANABEE, M. G.: Annals ofthe New York Academy of Science, 47, p. 375.

(12) ADRIAN, E. D., and GELPHAN, S.: Journal of Physiology,1933, 78, p. 271.

(13) ADRIAN, E. D., and BRONK, D, W.: ibid., 1929, 67,p. 119.

(14) CREED, R. S., et ai: "Reflex Activity of the Spinal Cord"(Clarendon Press, 1932).

(15) BERGER, R : Archiv fur Psychiatrie, 87, p. 527.(16) BARRON, D. H., and MATTHEWS, B. H. C : Journal of

Physiology, 1938, 92, p. 276.(17) FESSARD, A., and MATTHEWS, B. H. C.'.ibid., 1939, 95, p. 9.(18) MATTHEWS, B. H. C : Proceedings of the Royal Society,

B, 1937, 123, p. 416.(19) HECHT, S., SHLAER, S., and PIRENNE, M. H.: Science, 1941,

93, p. 585.

ABSTRACTS OF PAPERS

A NEW METHOD OF PREDETERMINING THE REGULATION OF ALTERNATORSAT UNITY AND LAGGING POWER FACTORS

By D. HARRISON, M.Eng., Associate Member, and C. V. JONES, M.Eng., B.Sc, Graduate.(ABSTRACT of a paper which was published in August, 1948, in Part II of the Journal.)

All the standard methods of predetermining alternator regu-lation depend on an estimation of the flux distribution underfull-load conditions. Such estimation is difficult owing tosaturation and leakage, and to different reluctances of the mag-netic paths. These difficulties do not arise in the methoddescribed.

The vector diagram for a loaded alternator may be representedby Fig. 1, Fe, Fa, Fr being respectively the d.c. excitation, arma-ture reaction and resultant m.m.f.'s.

Fig. 1

Fig. 2 represents the vector diagram of the alternator runningat a low speed of TV r.p.m. and supplying full-load current to an

Fig. 2

inductive load of reactance Xe (at normal frequency) and resis-tance Re.

It is possible to choose the speed and the inductive load sothat the m.m.f. triangles of Figs. 1 and 2 are identical and thee.m.f. triangles similar. The flux distribution at the low speed

Messrs. Harrison and Jones are at the University of Sheffield.

is thus the same as that at the normal speed,conditions are readily shown to be

The necessary

j \ — .

= iV,(Ra + Re)IJ+ Vcos<f>

(1)

(2)

where V, I, Ns, <f> refer to normal load and speed conditions.An inductive load to give the required power factor [equa-

tion (1)] is connected to the machine, which is run at the speed N[equation (2)]. The excitation is adjusted until full-load arma-ture current flows. If Eo is the open-circuit e.m.f. correspondingto this excitation, the regulation for the power factor specified is

En-V x 100%

In Fig. 3 the curve gives the result of a direct load test, and theplotted points show the results obtained by the method described.

po

520

10. /

A

/

)

-

-10° 0° 20° 40u

Phase angle60° 70

Fig. 3.—Variation of percentage regulation with phase angle for a12-5-kVA salient-pole alternator.

The method is applicable to single- and polyphase alternatorsof the cylindrical, salient-pole and inductor types, and may beused to predetermine other alternator load-characteristics. Verylittle power is needed to carry out the tests, and the results givenin the paper indicate that the errors are of the same order as thepossible experimental errors.