US1994231A - Lightning arrester - Google Patents

Description

March 12, 1935. F. SCHROTER 1,994,231

LIGHTNING ARRESTER Filed April 5, 1929 INVENTOR FI'IZ'Z Schrb'fel' A TT ORNE Y Patented Mar. 12, 1935 LIGHTNING AnnEs'rEn Fritz Schriiter, Berlin- Schmargendorf, Germany, assignor to Radio Patents Corporation, New

York, N. Y.

Application April 5,1929, Serial No. 352,695

s Claims. (01. 250-275) This invention refers to a type of lightning arrester applicable to power lines and particularly to high tension power lines. It is a wellknown fact that the lightning surges in a high tension line consist of impulses of very short duration but of very considerable energy. Therefore, a device to discharge this energy to ground the line and the impulse voltage are subdivided between the condenser units and eachof the glow discharge units will receive a difierent fraction of this voltage suitable for producing the desired action in this arrester. v r

The object of my invention is to secure an arrester. giving a high tension potential and ca pable at the same time of carrying a high discharge current. i

Another object of my invention is to produce anIarrester-which would respond within a very short interval of time, about one-thousandth of a second or less. 7

Another object of my invention is toproduce a structure to withstandthe heavy discharge of current. V

A further object of my invention is to provide a method of securing anatmosphere within said arrester which is suitable for its proper function.

A further object of myinvention is to-provide a method of providing terminals within my arrester suitable for its function.

I have describedmy invention in reference to the accompanying figure, which shows a glow discharge tube with proper terminals and proper-internal construction to accomplish the objects in view.

In thisfigure, 1 represents a glass vessel preferably oi the kind knownaspyrex glass or quartz which can withstand high temperature and high structure which would give a gas-tight separation between the upper and lower parts of the vessel. 7 1

I have mounted the terminals in the elongated upper and lower portions of vessel 1 as follows:- I '5 A funnel of reduced diameter consisting of pyrex glass or quartz is sealed on to the vessel 1. Within said funnel, a copper or nickel lead '7 is mounted. Thislead is sealed in the end of the vessel 1 and on the outside is attached to a metal cap Swhich is held to the end of the vessel by cement 9. The extreme end of the lead 7 carries an enlargement 10 which just clears the wall of the funnel 6 .and'toqwhich is fastened the electrode 11, consisting of some. high melting point metal such as tungsten molybdenum tantalum or some other similar material, especially those belonging to the 5A or 6A chemical group of the periodic table of Mandelff' as revised by Thompson. This metal electrode is surrounded by a 0 shell of magnesium or some other material of the alkaline earth group or even an alloy of magnesium and aluminum. On the inside of this shell, I place a pressed compound consisting preferably of magnesium powder and barium oxide, 25 but which may also be any other easily reducible material mixed with an oxide or salt of one or more metals, the latter being in each case, more electro-positive than magnesium. In other words, I may use the salt or oxide of any alkaline. metal 30 or earth alkaline metal such as the materials belonging to groups 1 and 2 of the periodic table of chemical elements (Mandelfi table as revised by Thompson). This mixture is'prepared by mixing, say magnesium dust with barium oxide in proportion of .5 or .7 to 1, drying the mixture in vacuum and pressing it afterwards to a solid body under high pressure. The best way to do this is to press this material inside of the magnesium shell by means of a suitable pressing device while the tungstenor tantalum rod with the surface roughened, is held near the center. The electrode may be assembled in this manner and mounted on the lead '7 before sealing it into the vessel. The electrode .is further treated after the tube is filled with gas in a manner described below:-

The atmosphere which may be used in this arrester, is preferably a rare gas, for example, a mixture of helium and neon at a pressure or" from .1 millimeter to .5 millimeters of mercury. I have found that this gas will be more satisfactory for the purpose of securing high voltage than the argon on account of the fact that the length of my arrester is limited by the length of the condenser to which it is connected and that therefore, a gas with high internal resistance is necessary. The suggested mixture of gas will prevent occasional discharge at normal pressure. windings of the discharge path through the helix increases the length of the discharge path and therefore, the potential to be applied to the tube before a discharge can occur in spite of the relatively short distance between the electrodes. With this arrangement, I expect that the discharge may take place at about double the nor-- mal operating voltage.

After introducing helium and neon, I furthermore may admit a vapor of alkaline metal such as sodium or potassium or even of alkaline earth metal like barium. I may accomplish this through the filling tube 14 which is shown to have an enlarged portion 15 in which the metal to be vaporized 16 is inserted and heated by anexternal flame 17 during the process of filling.

After admitting a suflicient quantity of such vapor; I seal the vessel at the point 18, removing the filling tube 14. However, with the construction of electrodes as described, I may use an alternative method of introducing the necessary alkaline metal vapor... The best way to accomplish this is to pass some strong discharge through the arrester after filling it with rare gas and sealing it ofi. This discharge should be of high voltage and power, during which metallic barium is formed around the hot electrodes by the chemical reaction'of the barium oxide with magnesium, whereby barium vapors are formed which act to purify the inert gas and to decrease the cathode drop or in other words, to facilitate the formation of an arc in accordance with the function of these tubes.

'Having thus fully described the construction and method of manufacture of'my arrester, I wish it to be understood that I am not limited to the particular structure of the features of the method of preparation, except insofar as it is liinited by the appended claims.

What I claim is: 1

1. A high voltage lightning arrester comprising a closed vessel, a gaseous atmosphere in said vessel, a first and second electrode for carrying a heavy dischargecurrent, means consisting of a magnesium shell surroundingsaid first electrode and amixture ofreduciblematerial containing electro-positi've metal within said shell and in intimate contact with said first elec rode.

2. A high voltage lightning arrester comprising'a vessel of high melting point insulatirigmaterial, filled with a gaseous atmosphere; a tubular helix of high melting point'insulating material; a funnel for securing each end or said helix to the inside of said vessel; a pair of operating electrodes within said vessel arranged opposite one of said funnels each; funnel caps secured on the exterior of said vessel, and lead-in wires from said funnel caps to said electrodes.

3. A high voltage lightning arrester commising a vessel of high melting point insulating material, filled with a gaseous atmosphere at re duced pressure, the central portion of said vessel being enlarged; a tubular helix of high melting point insulating material; a funnel for securing one end of said helix to the inside of said vessel, the opposite end of said helix being secured by a funnel; means for supporting said latter The funnel; a pair ofelectrodes within said vesseldis-f posed opposite said funnels each; caps secured on the exterior of said vessel; and lead-in wires from said cap to said electrodes. 4. A high voltage lightning arrester tube; a pair of electrodes Within said vessel dis'- compri sing a vessel of high melting point material filled i with an inert gas atmosphere; a helical tube of high melting point material mounted integral posedopposite the openings of said tube a shell containing electro positive metal in intimate contact with said electrodes. f

5. A high voltage lightning arrester jcomprising aivessel of high melting point material filled melting point materi'alymounted within andine 'of' electro-positive material within :said vessel,

tegral with said'vessel' with its openings opposite said electrodes; a shell of magnesium surrounding i said electrodes; and a compressed mixture of reducible material containing electro-positive substance within said shell in intimate contact with said electrodes.

6. A protective device for material filled with a gaseous atmosphere "at revessel to provide an elongated discharge path high voltage electric circuitscomprising a vessel of high melting point therebetweenfor increasing the operating voltage of said device; and a supply of electro-positive material within said vessel in intimate contact with said electrodes for producing purifying ya- I pors through heatingby said electrodesupon the occurrence of a discharge.

'7. A protectivedevice for high voltage electric systems comprising a vessel of high melting point material filled with an inertgas atmosphere at reduced pressure; electrodes disposed withinsaid vessel; means for extending the discharge path} between said electrodes for increasing the operating voltage of said device comprising a convoluted tube of high melting point material mounted within said vessel with its openingsdis- V posed adjacent to said electrodes and a supply of reducible material containing .electro-positive substance in intimate contact withsaid electrodes for producing purifying vapors through heating by said electrodes uponv the occurrence of a discharge. V r

' 8. A protective device for high voltage electric systems comprising a Vessel of high melting point material: filled with an inert gas atmosphere at reduced pressure; a pair of electrodes disposed within said vessel; means for extending'the discharge path between said electrodes to increase the operating voltage of s'aiddevicev comprising.

'a convoluted tube mounted integrally with and inside ofsaid tube with its openings adjacent to said electrodes; a shell of electro-positive mate rial surrounding said electrodes and a compressedmixture of reducible material containing electro-positive substance within said shell and 1a intimate'contact with said electrodes for producing purifying vapors through heating by said electrodes upon the occurrence of a discharge.-;- a

FRITZ sensors-a.

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