US2007932A - Surge arrester - Google Patents

Description

S. RUBEN SURGE ARRESTER July 9, 1935.

Filed Aug. 23, 1950 INVENTOR .S mug/ Ru bcfl Patented July 9 1935 j i Tl" ,UNIT ED STAT-ES PATENT OFFICE SURGE ARRESTER Samuel Ruben, New Rochelle, N. Y., assignor to .Sirian Lamp Company, Newark, N. J., a corporation of Delaware 1 Application August 23, 1930, Serial No. 477,305 zolanns. (o1. 250 mm) This invention relates to surge arresters adapted to be used in electrical circuits to protect delicate apparatus from excess current.

One of the objects of the inventionis to pro- 6 vide a simple apparatus which maybe connected in any electrical circuit'which will effectively prevent surges of current above a predetermined amount.

Another object of the invention'is to provide 10 a surge arresterwhich'will lead away only the The invention has been illustrated in the ac companying drawing in which: 7 2o Fig. 1 is a front elevational view of my improved surge arrester; v p p Fig. 2 is an enlarged longitudinal sectional view of one of the elements shown in Fig. 1; and

Fig. 3 is a front elevational view of a modified form of the construction.

Referring now more specifically to the draw ing the invention is shownascomprisinglan envelope E0 of glass or other suitable material in:

tegrally formed with theusual press for supporting the elements of the device. A pair of electron emitting elements l2 and it may have theirjlower endsmounted upon two support rods I tandltwhich may be sealed in the press II and their upper ends welded to aconnecting rod .IB which may be sealed in a glass bead ll. A supportrod 18 may be sealed in the press Hand may extendsubstantially axially of the envelope to the upper end thereof Where it may be sealed in the bead l1. The support rod 18 may bepro- 'vided with a plurality of cross members H! which may extend outwardly with their ends pointed and terminating a short distance from the elements l2 and I3 as clearly indicated. Leadingin wires 20, 2|, and 22 may be connected respectively to the support rods l4, l5, and I8.

The electron emitting elements I? and I3 may.

each comprise a coil 23 (see Fig. 2) of resistance wire such as tungsten, molybdenum, tantalum, or nichrome and the outer surface of the coil may be coated with an electron emitting material 24 which may be any ofthe electron emitting materials well known in the art, such as the oxides of the metals of the alkali earth group or a mixture of these oxides. L

The envelope I 0 may be filled with an inert gas,

preferably one of the monatomic gases or mixtures of suchgases, such as argon, neon, helium, krypton, or xenon, and'if desired the conductivity may be increased by introducing a small amount of metal vapor such as the vapors ofmercury, rubidium, orcaesium.

The bulb is preferably flashed with magnesium provided in a small container 25 attached to a wire 26 which may in turn be attached to one of the supportrods as the rod I l.

With the elements mounted upon the press and the press sealed in the envelope ID as indicated in Fig. 1 the envelope may be connected in the usual manner with an exhaust pump and an oven placed over it to heat it to a temperature of 350 to 400 Coor to as high a temperature as the glass will stand without the glass deforming. A current may be also run through the filament to raise it to about 600 C. and the gases whichare driven off from the filament and other parts of the lamp are withdrawn from the envelope by the vacuum pump. This 'process is continued until all of the gases driven ofi have'been removed and a high vacuum of preferably .5 of a micron is obtained. 1 The absence of gas may be determined by the lack of fluorescence when high tension current'from an induction coil is directed against the walls of the bulb. 1

When no more gases are evident the filament current may be slowly increased to approximately 800Cf when it will have a bright red appearance which drivesout the binder in the electron emitting material and other gases which may be present. When again no more gas is found in the bulb the oven may be raised and the filament heated for a moment to approximately 1200 C. or slightly less when more gases are driven out and drawn out of the bulb by the vacuum pump until the high vacuum is again obtained. 7 f

The pump may then be shutv off and the filament current turned off and a slight amount of an inert gas such as neon at about mm. pressure may be admitted to the bulb and the fila ment current turned onagain and gradually increased. .Spots of localized discharge will then appear having a reddish color and will gradually increase and spread until a diffused bluish glow completely fills the bulb. This process appears to activate the electron emitting material and may be maintained until the discharge is uniform throughout the bulb'which usually takes less than ten minutes. During this time the current on the filament should not be raised too high so that the coating will not be destroyed or thrown off from the filament. If white discharge spots appear on the filament and support rods it is an indication that there are more gases or vapors within the bulb and the bulb should again be exhausted and the whole process of activation repeated.

When the activation is completed the filament temperature may be raised to about 1400" C. and then the vacuum pump again connected and the gas pumped out to remove any undesirable gas which may have been thrown off during the activation process.

When the high vacuum i again obtained the filament circuit may be disconnected, the filament current turned off, and 50 mm. of neon gas admitted into the bulb followed by about 150 mm. of argon. The bulb may then be sealed off and after the magnesium is flashed by external bombardment may be ready for use.

The metal vapor may be introduced into the bulb by placing a small quantity of a salt of the metal, such as the chloride, with the magnesium in the container 2%. When the magnesium is heated with the salt it will react therewith to liberate the free metal and form a salt of mag nesium. The free metal will condense on the walls of the bulb to be vaporized again when the bulb is heated in use.

When such a device is connected in a circuit the elements l2 and it are raised to electron emitting temperatures and emit electrons which appear to ionize the gas in the vicinity of the element forming a conducting path through which current will flow and which produces a region of illumination like a halo around the element, as described in the co-pending application of Chester H.13raselton, Serial No. 459,048, filed June 3, 1930. The conducting path surrounding the elements i2 and i3 will carry additional current and the cross-sectional area or" this conducting path depends upon the amount of current flowing in the circuit. Hence, the members 56 are placed between the elements 5 and I3 close enough to each to touch the edge of the conductive area when the normal current is flowing in the circuit. When a surge of current occurs the discharge around the elements 52 and 13 will increase in size and include-the members is and as the leading-in wire 2'? is connected to ground there will be a flow of current through the members iii, the support rod l8, and the wire 22 and the additional current will be dissipatcd and will not be felt in the circuit. Thus damage to electrical apparatus by a current surge be prevented.

In Fig. 3 a modified form or" .re invention is illustrated in which electron emitting elements 2? and similar to those already described may be mounted at their lower ends upon support rods 29 and 3e respectively which may be sealed in the press iii and at their upper ends upon a cross connector which may be welded orotherwise attached to a support rod 33 mounted in the press 3| and positioned substantially on the axis of the bulb. A rod 34 may be positioned adjacent the element 21 and may be provided with a plurality of metallic points 35 which are spaced a short distance from the element 2'1. The rod 34 may extend downwardly and may be sealed in the press between the support 29 and the center support 33. In like manner a support rod 36 may be provided adjacent the element 28. This rod may be also provided with a plurality of metal points 31 and may also extend downwardly to be sealed in the press between the center support rod 33 and the element support 30. Leading-in Wires 38 and 39 may be attached to the support rods 29 and 30 while the rods 34 and 36 may have leading-in wires 40 and 4| respectively connected to them. These last two wires may be connected together and to ground. The device thusconstructed, when surrounded with the ionizable gas as already described in connection with Fig. 1, will operate in a similar manner, the points 35 and 31 intercepting the additional discharge from a surge of current and the addition current will ground with the result that the electrical apparatus is protected.

While I have shown a particular type of electron emitting element, other elements may be used, for instance a single straight wire coated with electron emitting material might be used or the material might be coated intermittently on'saicl wire or on a coil, or the individual turns of the coil may be coated leaving-space between every two turns. 1 7

Many other modifications may be resorted to without departing from the spirit of the invention and I do not therefore desire to limit myself to what has been shown and described except as such limitations occur in the appended claims.

What I desire to claimis:

1. A surge arrester comprising an envelope, a filamentary wire within said envelope, a coating of electron emitting material upon the surface of said wire, a. mixture of 75% of argon and 25% of neon surrounding said wire and having a pressure of approximately 200 mm. of mercury,,and an electrode positioned in the vicinity of said wire but separated therefrom by gaseous space, said electrode contacting with the luminous space formed about said wire when an excessive current flows therethrough.

2. A surge arrester comprising an envelope, 2. pair of substantially parallel electron emitting elements connected in series within said envelope, a conductor support positioned between said elements, aplurality ofpointed electrodes on said support and extending into the vicinity of said elements, and an ionizable gas surrounding said elements and having a pressure of substantially 200 mm. of mercury, said electrode contacting with the luminous space formed about said elements when an excessive current flows there through.

SAMUEL RUBEN.

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