GB182923A - Improvements in and relating to electro magnetic switches - Google Patents

Abstract

182,923. British Thomson - Houston Co., Ltd., (General Electric Co.). April 12, 1921. Electromagnetic switches; magnetic blow-outs. - Electromagnetic switches are provided with a blow-out device associated with the iron structure in such a manner that a portion of the magnetic flux is shunted so as to dis rupt the arc. An electromagnetic series lock-out switch having a shunt-closing magnet 32 and a series holding-out magnet 31 is illustrated. The shunt magnet 32 has a core 33 clamped between fixed upper and lower magnetic plates 26, 24 respectively. The contact 14 is resiliently mounted on a bell-crank lever 11 pivoted at 12, the lower arm of the lever 11 being pivotally connected at 18 to a plunger 19 passing through the series coil 31. The lower end 21 of the plunger 19 is of reduced section and is surrounded by a relatively fixed adjustable magnetic sleeve 22. A closing air gap 25 is provided between the enlarged upper end of the plunger 19 and the plate 26, and an adjustable holding-open air gap between the upper end of the core 19 and the magnetic sleeve 22. Magnetic plates 35, 36 are disposed at opposite sides of the fixed and movable contacts 17, 14, being connected by strips 37. 38 of magnetic material to plates 24, 26 of the magnetic structure respectively. When the current in the series coil 31 rises above the lock-out value, the attraction at the holding-open gap 27 overcomes the attraction between the upper end of the core 19 and the plate 26 and the switch is opened. When this occurs a portion of the flux from the coil 32 is shunted from the gap 25 across the air space between the plates 35, 36, thereby disrupting the arc. An arc-shoot 39 surrounding the contacts is supported between plates 35, 36.