US1792302A - Safety valve for electric switches - Google Patents

Description

His Attorney.

Feb- 10, 1931. J. D. HILLIARD v SAFETY. VALVE FOR ELECTRIC SWITCHES Filed oct. 1, 1926 y Patented Feb. l0, 1931 UNITE-D sTai*as*l COMPANY, A coiaroRA'rroN oiiNEw ironia,Z

SAFETY VALVE Fon. annemarie.; :swiiiciinsj Application ined october 1,1926. 'seriaiiva 138,371. i'

My invention relates to electric switches and particularly to switches of the fluid break type whereinthe contacts separate beneath the surface of an insulating' fluid. Wlheii anl lti arc is drawn in insulating fluids commonly used in such switches a certain amount of gas is formed due principally to the decomposition of the liquid, the amount depending upon the value of the current and voltage interrupted and the length of time that thearc continues. In ordinary use the amount of gaspressure generated in the switch is not excessive, the gas being commonly vented i through a relatively small orifice and may be lr5rconducted away where it can do no harm.

If, however, an accidental breakdown should occur in the switch such as to cause a con* tinuous arcing under short circuit conditions theV gas would be generated at such a rapid i'ate that the venting orifice might not be s'uliicient to allow its escape and eventually a pressure might be built up suflicient to rupture the switch tank.

An object of my invention is to provide im provedmeans controlled by a predetermined pressure in the vswitch tank for quickly relieving the pressure.

My invention will be better understood 1 from the following description taken in conf iiection with the accompanying drawing, and

its scope will be-pointed out iii the-appended claims.

Referring to the drawing, Fig. l is an ele vatioii with parts broken away of a switch iiivolving my invention; Figs. A2 and 8 are enlarged detail cross-sectional views of the discharge pipe of the switch showing the relief valve and operating mechanism therefor. Y

310 `The switch shown inV l comprises aY closed receptacle vformedby a tank l and a -Y cover:V 2 through which extend-'the insulator bushings 3 carrying the terminals 4 and the contact operating mechanism, not shown. Y For illustrative purposes only, I have chosen to'show .the switch llof the explosionchamconnected by a bridging-member 7i to'wliich is conne'ctedithe operating rod 8. `Atene side of casing l0v containingzthe switch operating mechanism yI have shown the vent pipe 11 which preferably.-v extendsfrom the switch to avpoint-outside of the buildingyin which the vswitch is housed.: The ventingy orifice coinmunicating with this pipe is preferably made relativelysmall.'F A

'.IAt Vthe fother side of shown'theve'ntpipe V12 ,which also preferably is arrangedV to dischargegas and liquid, at a the. casing io'i have e JOHN D. HILLLARD, or scHENEcTADY, newI YORK, Assis/fixiert Toenivnniinriiinemitrc,

pointl where itIcan-donodamage; such-as outsideof-ntheY buildingV lwhichhouses the Y switch. Thel orificelby which this pipe com- *municates With-'theiiiteriOr ofthe switchis not restricted -butthe :passageway isnormally closedbya valve fof relatively large size so that when it opens due to excessive pressure within theV sw'itrc'hztank, for example, due to a breakfdownQ-ora yfailure ofthe switchfthe. pressure may Vbe, quickly'relieved or `at Vleast .preventedfrom.building upto a dangerous value.- VI' have shown the vdischargepipe 12 providedwith: van intermediate iianged section 13to which vit is .secured as `for` example hy bOItslLLf` .Section-13 is shown having an inwardly eXtendin'g-flangel in which is formed'the seat for'thevalve 16.' The valve n f is guided by the ring 17 yconnected tothe seclti'on'l?)V by suitable struts .18 andv is limited in ,its opening movement by thespider 19 ,which is securedto thevalve bythe screw stud 20.V Thevalve isnormally heldv orthr-ust against i the seat by toggle mechanism comprising the` Elinks 22f-and 23.1- Link 22 pivotally connects .with the aforementioned stud 2O and link23 isV connected pin31 withlink 22 andby pin a.mutui@ Sara atwhieiiauaisiieia by the Y 'spider25fwhich isboltedfto the upperlend of the Sectionll.. Thespider has 'a downward. im?? Y extension 27 which supports a screw stop 28 which by engagement with the upper link 23 l limits the amount of overset that the toggle may take. To insure proper resetting of the valve after an opening movement and the desired oversetting of the toggle, I have shown the spring 30 attached to pivot pins 31 and 32 and having the bent end 33 arranged to engage the stud 24. It will be seen that the toggle automatically resets itself and iirmlyv holds the valve closed `untilthe pivot pin 3l is pushed past center to allow the `toggleto buckle. Formed in the valve 16 is thesmall cylinder 35 in which slides the piston 36 hav- Vand consequent reseating of the valve upon predetermined decrease of said pressure.

v In witness whereof, I have `hereunto set my hand this 30th day of September, 1926; f JOHN nD. HILLIARD.

ing the ro'd 37 passing throughthe vented l screw plug 38 in the upper end 'of the cylinder. VSpring 39 normally holds theV piston down against ashoulder on the cylinder wall forming its seat. The opening leading to the piston valve 36 is covered by the screen l0 to protect the valve `fromapi-ojected vmass 0f insulating liquid which might cause it to 0perate at a point below vthe required static pressure at which it was set. The pressure at which the piston valve will operate may be varied by adjustment of the screw plug 38. The lower link 22 of the toggle is lshown provided with a lateralextension 41 which when pressed with sui'licient force by the r0d37 moves the toggle pin 31 over center and allows'it to bulle. The adjustment is such that the pressures produced in the tank by the normal operation of the switch will not be through the restricted orifice in ventv pipe 11. In the event of a break-'down in the switch or other cause of abnormal pressure therein,

the piston valve 36 inresp'ondingto such abnormal pressure will jtrip the toggle and alf low thel large Valve t0v release the `gas and j liquid, thereby preventing ja further risein p pressure.

wVliatIclai-rn 'as V:new and desireto secure by Letters Patent of the United States, is `z- *1.V A valve structure adapted for the quick relief of excessive'pressure in 'a tank comprising means forming a valve seata valve-therelsufficient to cause thev large valve 16.to open, the gas 'formed at such operations escaping v ior,a to' 'Gle for normall kholdin the valve v ge Y g on'the seat, and means carriedvbythe valve f and subject to the pressure withinv the tank c tion retaining the valve on its seat'.

for releasing the toggle. 2. Apparatus adapted for the quick relief of excessive pressure in an enclosedA fluid i Ybreak switch comprising a valve seat,'a valve, a toggle for retaining the valve on the seat,

pressure responsive means for tripping the toggle thereby to allow the valve to open una der the influence of and to relieve the pres-V Y sure, and a spring arranged to effect'thelsubsequent restoration of the toggle'to the posi- 3. Apparatus adapted for the quick relief of excess pressureinan enclosed uid break .switch lcomprising a lvfalveseat7 a valve kv.for`

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