| 摘要 |
<p>938,571. Protective arrangements. SPERRY RAND CORPORATION. May 6, 1960 [May 12, 1959], No. 16089/60. Class 38 (5). A fault indicating arrangement for a polyphase circuit comprises current transformers 10 ... 12 which saturate at normal load currents so as to produce third harmonic voltages in their secondary windings 16. . . 18 which are connected in series to supply a fault indicator 2 through a rectifier 19. Under normal conditions the components of fundamental frequency cancel out and the indicator is maintained energized by the rectified sum of the voltages of the third harmonic frequency. In the event of an open-circuit or other fault in any of the supply conductors 6 . . . 8 the sum is reduced and the indicator indicates the fault condition. Figs. 3 and 4 (not shown) illustrate the invention applied to two-phase three and four-wire circuits.</p> |
