US1808517A - Metal vapor rectifier - Google Patents

Description

June 2, 1931. R. a. BERTHOLD 1,8 3,5 7

' METAL vAPoR RECTIFIER Fil ed July 11, 1928 Patented 1a.. 2,1931

UNITED STA nunonr e. naarnonn, or naanrn-smnnnssrm, (1mm, assrcnon. ro smmnnssonncxmu'wnm AKTIENGESEILSCEAFT, OF BERLIN-SIEHE'NSSTLD'I, GERMANY,

A CORPORATION OF GERMANY 'nE'raL varoa anc'rrrmn.

Application 111m m 11, 1928, Serial at.

My invention relates to improvements in metal vapor rectifiers, and more specifically to rectifiers for convertingalternating current of high voltage into direct current. The use of metal vapor rectifier plants for converting alternating current of .high voltage into-direct current is limited by the comparatively low stopping voltage of such rectifiers. This stopping voltage is limited at the top by the following phenomenon: In the dis charge space of the rectifier are contained large quantities of ionized gas, consisting of positive (heavy) mercury ions and negative (light) electrons, which are continuously supplied by the constantly burnin ignition arc, and are thus available indepen ent of a very short life of the ionization in all phases of the rectifying process.

If now in the stopping phase the rectifier anode becomes negative in relation to the rectifier cathode, the existing positive mercury ions originating from the ignition arc drop with a velocity correspondingwith the great ti-ve face of the anode and directed away from it. This current of vapor then also catches the ions streaming towards the anode due to' the electricfield, and thus prevents the excessive heating of the anode. During the time the anode carries the working current, the positive ions are driven away from the anode due to its positive potential, in any case with- I in the extent of the anode drop. The artificially produced flow of vapor thus acts during this positive anode potential. It appears, however, preferable not to let the stream-of vapor extend itself'in the direction of flow of the positive ions substantially beyond the sphere of the anode drop, because It W111 otherwise half wave in the same direction as the Y 291,819, i in Germany July 15, may

attempt to destroy the condition of the quasie neutrality in the arc discharge and might thus cause a comparatively high voltage loss 1n the rectifier also in the. direction of the flow. If it is thus impossible to produce an artificial stream of vapor within the range of the anode drop sphere only, a controlled stream of vapor directed away from the anode may also be used according to myeinvention, which streams from the anode towards the cathode during that half wave of the feeding alternating currentonly, during which the anode carries no current.

Mercury vapor rectifiers are already known in which in order to avoid backfiring the anode ishoused in a chamber, which stands under a lower discharge cham er. To. obtain this lower pressure the anode is envelo d by a shell open towards the cathode an the outer face of this shell is swept by a stream of vapor directed towards the cathode. This stream of vapor then exerts an exhausting action on the inside of the shell surrounding the anode. In contrast with this arrangement it is ac-, cording to my invention not intended to prevent the backfiring by an increase of the .vac-

-uum at the active anode face, but by a current of vapor directed away from the anode face. While in the known arrangement the impingmg of gas ions on the anodeis to be reduced by mcreaslng the vacuum, the positive gas ions flowing towards the anode are accordmg to my invention blown away by a countercurrent set up.

In the drawings aflixed hereto and forming part ofmy specification two embodiments of my invention are illustrated by way of example.

Fig. 1 is a vertical section through one constructioirof my improved rectifier, in diagrammatlc representation, and

ressure than the remaining Fig. 2, a vertical section through another construction ofv improved rectifier.

L1ke parts are indicated by likenumerals of reference in both figures of the drawings. Referring to Fig. 1, 1 is a mercury cathode ofa glass rectifier 2, and 3 the anode. The

anode 1s designed as a sieve, and mercury vapor is constantly supplied to itand'trav erses the perforations ofthe 'sieve from back to front. To bring this about I provide a mercurycup 4 in communication with the cathode 1 and in which mercury vapor is constantly generated by means of an auxiliary heating arrangement. This heating arrangement consists in Fig. 1 of a heating spiral 5 and the feeding battery 6. The mercury vapor enerated in the cu 4 is conveyed to m the bac of the sieve ano e by means of the tube 7. For condensing the mercury vapor emanating from the cathode 1 as well as from r the anode 3 the rectifier bulb 2 is in its upper art surrounded with a jacket 8 traversed y a cooling medium. Referring to Fig. 2, it will be seen, that the mercury vapor stream or spray directed away from the anode face is generated during the 4 half wave of the feeding alternating current, during which the anodecarries no current; The anode is again designed as a sieve. The chamber at the back of the sieve communicates by the tube 18 with an auxiliary mercury vapor rectifier bulb 10. This auxiliary mercury vapor rectifier bulb is fed with alternating current and possesses two mercury electrodes 11 and 12, of which the electrode '12 acts as cathode.

- For this purpose an auxiliary discharge is maintained at the electrode 12 by means of alternating voltage duringwhich the anode carries no current.

3. In a metal vapor rectifier, in combination, a sieve-like anode,.and means for producing a stream of vapor passing through the perforations of the anode sieve and directed away from the active anode face, said means creating the flow of vapor only during that half wave of the rectified alternating voltage during which the anode carries no current.

4. In a metal vapor rectifier, in combination, a sieve-like anode, an auxiliary rectifier bulb fed with alternating current, a connecting tube between the auxiliary rectifier bulb and the metal vapor rectifier, said auxiliary rectifier adapted to generate a flow of vapor passing through the sieve-like anode of the metal vapor rectifier and directed away from the active anode face.

5. In a metal vapor rectifier, an anode designed as hollow body, sieve-like perforations in the active anode face, an auxiliary rectifier bulb fed with alternating current, a connecting tube between the auxiliary rectifier bulb and the metal vapor rectifier, said connecting tube opening into the cavity -of said anode. ,1

In testimon whereof I aflix my signature. UDOLF G. BERTHOLD.

the source of direct current 13 and at the electrode 14. Through the auxiliary rectifier bulb thus flow'in phase with the, for instance, positive half wave of the feeding alternating current from the electrode 12 to the electrode 11 rushes of current, which also produce corresponding intermittent rushes of mercur vapor between the two electrodes. Thesepu sating streams of mercury vapor are then also'supplied'by the tube 18 to the anode? of the main mercury vapor rectifier and produce at it the desired flow of mercury vaporu It will be understood that my improved metalvapor rectifier may be equi ped with known ap aratus for controlling t e current between t e anode and the cathode:

Various changes and modifications may be made without departing from the spirit of I desire, therefore, that only such limitations should be placed thereon as are imposed by r the prior art. y

' I- claim as my invention: 1. In a metal vapor rectifier in' combination, -a sieve-like anode, and means for producing a stream of vapor'passing through the perforations of. the anode s'ieve and directed away from the active anode face.

. 2. In' a metal vapor rectifier, means for my invention and the following claims and generating a flow of vapor from the active -anodefdce of-the rectifier and directed away from it, said means creating theflow of vapor u only during that half'wave of the reetified

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