| 释义 |
self-exˈciting, ppl. a.
[self- 1 f.]
a. Electr. Designating a dynamo-electric machine that excites its own field. Also transf., with reference to the hypothesis that the earth's magnetic field is generated in the earth's core by a mechanism analogous to that of a dynamo.
1884C. G. W. Lock Workshop Rec. Ser. iii. 119/1 Self-exciting machines. 1922Glazebrook Dict. Appl. Physics II. 195/1 The great advantage of direct-current machines is that: (i) They can be made self-exciting. 1954E. Bullard in G. P. Kuiper Earth as Planet iii. 129 The possibility that the motion of the material of the core could cause it to act as a self-exciting dynamo. 1971Sci. Amer. Dec. 80/1 The influence of the Coriolis force on the motions of the outer core is thought to be critical to the operation of the self-exciting dynamo that generates the main magnetic field of the earth.
b. Radio. Self-oscillating; (see quot. 1943).
1922Proc. IRE X. 251 The basis of super-regeneration was the discovery that a variation in the relation between the negative and positive resistances prevented a system which would normally oscillate violently from becoming self-exciting. 1943Gloss. Terms Telecomm. (B.S.I.) 69 Self-exciting sender, a radio sender in which the oscillator determining the frequency also generates the radio⁓frequency power.
So self-excitation; self-exˈcite v. intr. and trans.; self-exˈcited ppl. a., self-exciting.
1908J. G. Horner Encycl. Pract. Engin., Self-Excitation, the characteristic of a dynamo which enables it to build up a magnetic field upon the rotation of its armature from the residual magnetism of its magnet poles. 1921J. H. Morecroft Princ. Radio Communication vi. 562 A possible arrangement of self-excitation, in which the phase of the voltage impressed on the grid is adjustable. Ibid. 563 (caption) Conditions occurring in the self-excited tube. 1922Glazebrook Dict. Appl. Physics II. 196/2 It is also necessary that the winding should have a sufficiently low resistance, otherwise self⁓excitation will not occur. Ibid., At this speed..the machine will not self-excite. 1940Amateur Radio Handbk. (ed. 2) xvii. 245/1 Developments during the few years prior to the war tended to relegate self-excited transmitters into the background. 1962Newnes Conc. Encycl. Electr. Engin. 672/2 An induction generator can be self⁓excited by means of a capacitor. Ibid. 673/1 Unwanted self-excitation with dangerously-high voltages may occur in induction generators. 1977Jrnl. R. Soc. Arts CXXV. 764/1 Before the appearance of the self-excited dynamo in 1867 it was by no means obvious that magneto-electric induction would power the world's industries. |