| 摘要 |
<p>1,157,706. Photo-electric checking apparatus. ETABS MERLIN & GERIN. Oct. 25, 1966 [Nov. 4, 1965], No. 47824/66. Heading G1A. [Also in Division H2] A photo-electric system is used to keep a continuous check on the functioning of the control element of a high voltage circuit-breaker. The circuit-breaker comprises a coil 18 which is caused to open contact 17 in the high voltage line when a silicon controlled rectifier 26 discharges. This occurs when a tripping order is received at the relay 12 at earth potential, causing flashing of tube 11, the flash being detected, via light guide 15 and lens 34, by photocell 16 to cause ignition of the SCR 26. Power for the latter comes from the line via transformer 20, rectifier bridge 21 and SCR's 22, 23 to charge up capacitor 19. The most common fault in such a system is short-circuiting of the SCR 26 (which is therefore doubled or tripled for safety). If such shortcircuiting occurs, there will be no voltage across the terminals of the SCR 26 and the lamp 28 connected between these terminals will not light. Thus no light will be received by photo-cell 14 via light guide 31 and lenses 32, 33. As a result, the gate 13 (e.g. an SCR) will be gated "off" and in the event of a tripping order, the flash-tube 11 will not light up. A circuit breaker system may comprise a number of circuit breaks in series in the high voltage line, each provided with its own tripping circuit P, but all these latter circuits P being operated by a single flashtube 11. A number of control means 13, one for each tripping circuit, connect with the flashtube. If any one of the SCRs fails, the tube 11 is rendered non-operative and none of the breakers is operated in the event of a tripping order at 12. After a fault has been detected and eliminated and the contact 17 closed again to remake the high voltage line circuit, the lamp 28 may take a certain time to reach full light output, thus delaying the re-opening of gate 13, and making the system unresponsive to a tripping order. A capacitor 30 is thus provided to apply an overvoltage to the lamp after reclosure of contact 17. In a modification, the detector 16 and SCR 26 are combined as a photo thyristor. The light guides may be of plastics material and inert gas filled. They may be combined as a single unit or be substituted by a single guide.</p> |
