GB587668A - Improvements in electric circuit breakers with arc extinguishing devices - Google Patents

Abstract

587,668. Gas-blast switches. BRITISH THOMSON-HOUSTON CO., Ltd. May 31, 1943, No. 8694. Convention date, May 29, 1942 [Class 38 (v)] A load-break disconnect switch comprising a blade 4 bridging contacts 1, 6 has an arcextinguishing contact structure 7 and series disconnect contact 13 in parallel with, and operating after, the blade. The blade comprises two spaced strips embracing the contact 6 and housing the structure 7 between them, the arrangement being that when the blade is operated by means of a pole applied to ring 14, the contact 13 is held back by a latch 26 to produce separation of the contacts in structure 7, and is then released by slipping under the latch to cause those contacts to reclose in the open (dotted line) position of the blade 4. In reclosing, the contact 13 deflects the latch and engages contact-strip 25 to make the circuit before blade 4 re-engages contact 6. The structure 7 comprises a two-part housing 8 enclosing a rotor 15 which is provided with bearing surfaces 32 for the housing 8 and stub axles 18 for rotation in the blade strips. Roller-contacts 9, 11 on the rotor surface co-operate with contacts 10, 12 on the housing-interior, the contactsupports 9', 11<1> being outwardly spring-biassed at 16 and connected together by braid. The housing 8 carries a toothed segment 19 meshing with a pinion 20 which is rotatable on a pin 21 in an attachment 22 on one blade-strip and engages a spur gear 23 carried on one axle 18. Thus when blade 4 is opened, contact 13 moves until arrested by latch 26, the further movement of blade 4, as housing 8 rotates anticlockwise on it, causing the rotor 15 to rotate clockwise to provide two series-breaks, a spiral spring 29, Fig. 3, restoring the housing and rotor to their normal positions at the completion of the opening movement. The housing and rotor have cylinders 33, 34 of fibre, methyl methacrylate, or other gas-evolving material, forming an arc-quenching space between them. The arc-gases escape from contacts 9, 10 into a copper-wool muffle 37 in a conducting tube 42 between contacts 10, 13, and thence through slots 44 in the tube 42 into a space 45 and exhaust passages 46. The gases from contacts 11, 12 escape through passage 35 in conducting block 35<1> into copper-wool 37 in a tube 36, the block 35<1> being connected at 39 to a conductor 38 having sliding engagement with a blade strip 4. In a modified form of gas escape, Fig. 7, each arc space 53 communicates round the edge of cylinder 33 with grooves 52 terminating in a corrugated metal sheet muffler 54.