US2855545A - Circuit breaker devices - Google Patents

Description

Oct. 7, 1958 NORBERT R BENCHEMOUL 2,

Now BY CHANGE OF NAME NORBERT R. BEYRARD cRcuT BREAKER DEvCES 2 Sheetssheet F11ed May 4' 1953 0F NAME BE RARD NORBERT 0c[. 7, 1958 NORBERT R BENCHEMOUL 2,855,

Now BY CHANGE OF NAME NORBERT R. BEYRARD CIRCUIT BREAKER DEVICES F11ed Ma 4, 1955 2 Sheets-Sheet 2 United StteS atent o CIRCUIT BREAKER DEVICES In my U S patent application Sefial NO 302 789, iled August 19Z fol "I]iquid IeSiStanCe Electfical Apparatus," Which became Patent 2 649,Z6, dated Au guS 18 19j3, I have descfibed an apparatus through Which an elect!ic cunent is intended to be passed and which includes at least two electrodes placed pposite t0 each other aIld encsing a chambef of Sn1all volun]e Which conn1unicates with a vessel containing a conduc tion liquid, by Ineans of at least two channels Which present a certain resistance to the passage of the liquid An apparatus of this kind operate8 in the f01lowing manner;

AS long aS the strength of the cufrent vvhich passes through the chanber between the tw0 electrodes does not exceed a certain value, known as the "threshold" Value the conducting liquid remains in the uid state and the apparatus Oefs only a very SInall resistance t0 the passage of the curre11t ()Il the other hand, aS Soon as the current density exceed3 the threshold value, there re- Sults a vaporisation of the liquid in the Said Chanber and expulsi01, at least t0 SOIne extent, Of the liquid t0wards the vessel, in Such a vvay that the resistance 0efed to the passage of current betvveen the electrodes increases rapidly and thus there is produced, at least mon1enta1ily, a limitation of the curfent' In actua1 fact the liquid Which has been expelled can only return S10vvly fronl tlle vessel into the chaInber because of the Tesistance to the OW of the liquid offered by the channels.

TT16 present invention has for its object the application of such an apparatus to the production of an excess current circuit-breaker device.

The circuit)reake device in accordance With the invention includes, itl Series vvith the Supply circuit of an insta;llation, at least one apparatu3 c0mprising two oppositely arranged electr0des forn1ing between them a chanber 'of` SIT1a11 volun1e, vhich chanlber C0Inmunicate8 Vvith a vessel containing a conducting liquid, )y means of Passage8 0eTing a certain l eSStanCe to the 0 Of the liquid and, in shunt t0 the Said Supply circuit, between the Said apparatus and the installation, the Winding of a Tninimum curfent circuit-breaker designed t0 -0pen the Said Supply circuit vvhen for any particular reason, the current taken by the' installation increases to an abnorn1a1 extent, there is produced in tlle apparatus, at least a partial vaporisation of the conduction liqlli(l, such that the Tesistance bet/een the electrodes rises to a value much highe1` than that Which obtains -Vhen the chan]ber iS entire]y filled Vith Hquid.

In consequence, the voltage at the ternTinals of tlle c0i vvinding falls avvay Sharply and thiS results in the openipg 0f` th ninin1un1 Cuffent cicuit-bl'eak 1. 4 t the Sa[ne tiIne; the il1 T dll(ti(l1 0f hiS high resistance into he Cir cuitdi1Tinishes tlle value0f the 0v`erioad current S0 hat the bT ak ng 0f the Supply ciruit by the Ininin1unl current circuitbraker can be effected When `the current has fallen to a Teasonable value which considerably sin1p]i ies the circuit-breaker roblen1.

There is thus obained the Tesult, t0 all apPearances parad0xical, that an installation is protected against ex cessive current over10ad by Ineans of a 11TininluIn current circuitbreaker vhich, furthermore, breaks the current, not When this is a maximum as is the case with normal circuit-bfeakers, but when this current has fallen back to a value which Inay even be less than the nornal curfent value taken by the installation.

The advantages of such a cicuitbreaker aTrangenent are i1111Tediate, for it is clear that, in these circun1stance8, the contact studs of the circuit-bfeaker device run little risk of being damaged at the moment when they separate and that it is unnecessary, becallse 0f the low value of current concerned, to provide a bl0Vv-out'0f the electric arc Which is likely to be produced between these studs' In addition, because 0f the Teduction in the current over- 10ad value before the )reaking of the circuit, the installation itself is thus pfotected against high excess v()t ages Which quite usually occur When the current iS br0ken at the moment of its maximum value In one convenient forn1 0f en1b0din]el1t of the inventi0I1, the chan1ber enclosed y the electr0des is provided With small vent holes which auow a partial escape of the vapour vvhich is givel1 0 In this vay, the expulsion of the li( uid contained in this chan1ber into the vessel can b5 Slowed down, thereby ensuring a Sharply rogressive reduction in the values of the ovefload currel1t There iS I10 accesry device which is absolutely neces- Sary to the 0peration of this circuit-breake1 device. IIOW- ever, in order t0 per[nit of action being taken at the in- Stallation vvhel1 an ovef10ad tends to occur and to increase, )y reason of a fault vvhich bec0nes Inore Seriou8, the circuitbreaker n acc0fdance vvith theinvention ITlay be COInpleted by a wafning device' In practice, in Such a Way, a pulsating condition tends to be set up in the apparat[18, Since a partial vap0risation of the liquid in th chanber, resulting in a reducti011 il1 the Strength of th cufrent, is foll0vved each tile by a return of this liquid from thevesse1 to the chamber and so on At a point in the circuit after the apparatus and particularly at the terminals of the winding of this ci1cuit-breaker, there are thus produced pu18atory voltages which can be used t0 0perate a vvinking device. Before the circuit is )r0ken the 0ccurrence of this vvinking thus vvarns the user of the existence 0f al1 abnorn1al condition The liquid used in the apparatus Inay vvith advantage consist of an electrolyte ...and the apparatus is prefera,bly constructed in Such a nlanner that the internal v01tage drop betvveen the electrodes is less than the p0larising v01tage S0 as t0 av0id any electrolytic phenomena in the apparatus very large number of electrolytes are suitable for this use, and il1 particular use may be made of solutions of potash 0I' potassiu111 carbonate The circuit-breaking device in accordance vvith the in venti011 may be applied to all silgle or I)0lyphase alternating cuTrent distribution Systen8 'and, as vvill be seen later, it n1ay be provided to protect one or Inore phases of such a distributi011 System.

The blade contact of the n1inin1um current `circuitbreaker Inay be arranged in such a nlanner that they eI Sure the disconnection of all the cables of the distribution Systen1, in order to prevent a part 0f the installation or of the apparatus being left under voltage aftel the circuit is broken.

The Cirouit-breaker device i1 accordance with the in venti011 is )articulafly suitable fol' i11stallati011s which include m0tors, the starting of Which iS effected by the internlediary of a li llid fhe0stat eSiStance II1 this case the chamber formed between the electrodes of the circuit-breaker device in accordance vvith the invention,

Images