US2480282A - Lightning arrester - Google Patents

Description

Allg 30, 1949 J. A. BlGwoon 2,480,282

LIGHTNING ARRESTER Filed July 27, 1945 5l.; @kw

ATTORNEYS Patented Aug. 30, 1949 LIGHTNING ARRESTER John A. Bigwood, Stamford, Conn., assignor to Air Reduction Company, Incorporated, a corporation of New York Application 'July 27, 1945, Serial No. 607,451

(Cl. Z50-27.5)

10 Claims.

This invention relates to devices for protecting electrical apparatus fr'om injury by abnormally great electric currents, such for example as lightning discharges, accidentally produced violent surges of current, and the like. More particularly the invention relates to lightning arresters of the type in which three spaced electrodes are located in a sealed glass envelope containing an ionizable gas.

Lightning arresters of the kind referred to are generally associated with the electrical device to be protected by connecting two of the electrodes, called the line electrodes, to opposite sides of the device and by connecting to ground the third electrode which is therefore called the ground electrode. Any abnormal surge of current which would otherwise injure the device protected by the lightning arrester causes a discharge between the line electrodes of the arrester and ionizes the gas in its glass envelope and shunts the surge of current around the device. At the same time the discharge between one of the line electrodes and the ground electrode dissipates the surge to the ground.

It has been found in practice th-at the passage of abnormally large electric currents through arresters results in a considerable evolution of heat, so much so that when the arrester has electrodes of the ykind described the electrodes or the wires making electrical contact with them sometimes become softened or even fused. As a result the electrodes may move from their original spaced relationship, thus altering the distance between electrodes and thereby the electrical potential required to effect discharge between the several.

electrodes. When large amounts of heat are evolved, the electrodes may become so far removed from their original spaced relationship as to touch one another. The arrester is then likely to short-circuit the device it is intended to protect and loses much if not all its value as a protective device. It is particularly undesirable in connection with some signalling devices that a line-to-line short circuit be established.

One object of the present invention is to provide a lightning arrester or protective device of the electrode typewherein the likelihood of the electrodes becoming short circuited is eliminated or greatly reduced.

Another object of the invention is to provide means within the protective device or arrester whereby the heat .produced by abnormal electrical discharges is in large part dissipated or used up before it can injure the electrodes or the wires connected thereto.

A further object is to make such means continuous with the envelope or shell of the protective device.

Another object of the invention is to provide a protective device or arrester of simple construction, long protective life and mechanical stability.

These objects, and others that will hereinafter appear. are attained by the use of a glass insulating post having portions situated between the electrodes and which in the preferred form of the invention is continuous with the envelope of the protective device or arrest-er and has a stem portion situated between the two line electrodes and at its distal end an enlarged head portion which is interposed between the line electrodes and the ground electrode.

The accompanying drawing illustrates the invention as applied to several different types of arresters.

In the drawing:

Figure 1 is a longitudinal section through one type of arrester embodying the invention;

Fig. 2 is a longitudinal section taken on the line 2-2 of Fig. 1;.

Figs. 3.and 4 are partial longitudinal sectional views corresponding to Fig. l but showing modified and alternative positions of the head portion of the glass post relative to the electrodes; and

Fig. 5 is a broken perspective view illustrating the invention as applied to a different type of arrester.

Referring iirst to Figs. 1 and 2, the reference numeral I denotes the continuous tubular glass envelope forming the shell of the arrester, having at opposite ends re-entrant glass portions 2 and l. These re-entrant portions are commonly known as .presses. In press 2 are sealed the lead-in wires 4 and 5 and similarly in press I are sealed the lead-in wires 6. The lead-in wires are of the usual type adapted for sealing in glass. They may be welded to heavier pieces of electrodesupporting wire 1 for the purpose of obtaining greater mechanical stability.

The wires 1 are attached by welding or in some other suitable way to metallic electrodes 8, 9 and I0. Electrodes 8 and 9 are the above-mentioned line-electrodes since they are connected by means of the lead-in wires 4 and 5 respectively with the power lines supplying the electrical device to be protected. Electrode I0 is the above-mentioned ground-electrode and is suitably electrically grounded by means of the lead-in wires 6. The number and size of the wires attached to each electrode may be varied depending upon the mechanical strength desired in the structure, the

current to be conducted, and to a lesser extent n th available space. up glass post ll preferably integral with envelope I and press 2, has a stem portion Ila situated between electrodes 8 and 9. The stem portion extends beyond the electrodes and terminates in an enlarged attened head portion or button IIb. Fig. 1 shows the button IIb as interposed approximately midway between the line and ground electrodes. It may be in other spaced relationships as shown in Fig. 3 wherein button IIb is in contact with the distal ends'of line electrodes 8 and 9, or as in Fig. 4 wherein button llb is in contact with ground electrode l0. In

e case of Fig. 4 the use of button llb is not 1elslsential although in many cases it is desirable. When desired, the stem portion Ila of the post may be extended so as to make contact with ground electrode l0.

The envelope l is lled with a rarefled gas such as neon, or a mixture of gases which is adapted to become ionized under electrical potential and thus act as a conductor.

4The electrodes may, if desired, be coated with metals or metallic oxides which promote ionizan and conduction. u

t1OI'he stem portion of the post Il should not be so wide as to interpose an insulating barrier between the entire opposing surfaces of the line electrodes, `thus making electrical discharge between them dimeuit. simueny, the butt-.cn Hb should not present an insulating barrier between the entire adjacent surfaces of the ground and line electrodes.

The post l l may be formed by any of the methods known to those skilled in the art. In general, it suii'ices to have a glass tube or rod of suitable size, shape and length inserted along with the lead-in wires through a glass tube which on suitable heating and pressing forms the press 2 and the post il together with its button ilb. The details of such method are well known in the art and are not a part of this invention.

The post, being made of glass, is fusible. Since glass has a lower fusion temperature and somewhat higher specific heat than the materials usually used as electrodes, it follows that the presence of a substantial mass of glass will serve as a protective means to delay fusion of the metallic electrodes.

Fig. 5 illustrates the invention as applied to a diiierent type of arrester. The arrester shown in Figs. 1 4 is of the so-called double-end type, the electrical connections coming from both ends of the arrester. The arrester shown in Fig. 5 is oi the single-end type wherein. all electrical connections come from one end of the arrester. Lead-in wires 1i', 5' and 6' are sealed into and extend through press and are suitably attached to heavier wires which in turn are welded or otherwise suitably attached respectively to electrodes 3', il and it. Two of these electrodes are the line electrodes, the third being the ground electrode, their functions being the same as the functions of the electrodes of the arrester previously described. The size and spacing of the three electrodes is adapted to the specic characteristics desired in the arrester, but in general they are curved as shown and spaced uniformly about the axis of the glass post il', the spaces between any pair of electrodes being such as to give the desired breakdown voltage. The invention is not limited to any particular shape or size of electrode.

The glass post it' is similar to the post ii of the arrester of Figs. 1-4, being continuous with the press 2' and envelope I' and having a stem portion Il'a and a head portion or button Ilb. The diameter of button Il'b is suiiiciently large so that if the electrodes move in toward the post they will not make contact along their adjacent edges.

It will now be seen that in each form of the invention some portion of the glass post lies between the line electrodes themselves and some portion (whether the same or a diierent portion) lies between the line electrodes and the ground electrode in such a way as to prevent contact between the electrodes should they or their supporting wires soften and become distorted. In Figs. 1 to 4 the stem portion of the post prevents contact between the line electrodes and the button at the end of the post prevents contact between the line electrodes and the ground electrode, although as previously stated, in cases where the stem portion of the post projects far enough beyond the line electrodes, as in Fig. 4, the button may be omitted, and in that case the portion of the post which prevents contact between the line electrodes and the groundv electrode is the end portion itself of the posts stem. In the case of Fig. 5 the button at the end of the post preventscontact between the line electrodes themselves as well as between the line electrodes and the ground electrode. In each form of the invention the presence of the substantial mass of glass in the post serves as a protective means to delay softening or fusing of the electrodes for the reasons above stated.

In the speciilc description of the invention the device has been referred to as an arrester since one of its principal uses is asa lightning arrester, but it should be understood that it can be used for protecting electrical equipment from injury by any abnormally great electric current, whether produced by lightning or in some other Way.

I claim:

i. A lightning arrester comprising a glass envelope containing an ionizable gas, a pair of line electrodes and a ground electrode in the envelope, and a glass member within the envelope some portion of which lies between the distal ends of the line electrodes themselves and some portion of which lies between the distal ends of the line electrodes and the distal end of the ground electrode, the line electrodes having confronting areas between which no portion of said glass member lies.

2. A lightning arrester comprising a glass envelope containing an ionizable gas, a pair of line electrodes and a ground electrode in the envelope, and a glass post within the envelope some portion of which lies between the distal ends of the line electrodes themselves and some portion of which lies between the distal ends of the line electrodes and the distai end of the ground electrode, the line electrodes having confronting areas between which no portion of said glass post lies.

3. A lightning arrester comprising a glass envelope containing an ionizable gas, a pair of line electrodes and a ground electrode in the envelope, and a glass post integral with the envelope and projecting into its interior, said post having a portion which lies between the distal ends of the line electrodes themselves and a portion which lies between the distal ends of the line electrodes and the distal end of the ground electrode, the line electrodes having confronting areas between which no portion oi' said glass post lies.

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4. A lightning arrester for protecting electrical devices and the like comprising a glass envelope containing an ionizable gas, a pair of line electrodes and a ground electrode in the envelope, means for electrically connecting the line electrodes across the device to be protected, means for electrically connecting the other electrode to ground, and glass means in the envelope some portion of which lies between the distal ends of the line electrodes themselves and some portion of which lies between the distal ends of the line electrodes and the distal end of the ground electrode whereby contact between the electrodes is prevented in the event of their displacement due to heat involved during dissipation of an electric charge by the arrester, the line electrodes having confronting areas between which no portion of said glass means lies.

5. A lightning arrester comprising a glass envelope containing an ionizable gas, a pair of line electrodes and a ground electrode in the envelope, lead-in wires for the line electrodes, a press integral with the envelope and in which the leadin wires are sealed, and a glass post within the envelope and which is integral with said press, some portion of the post lying between the distal ends of the line electrodes themselves and some portion of it lying between the distal ends of the line electrodes and the distal end of the ground electrode, the line electrodes having confronting areas between which no portion of said glass post lies.

6. A lightning arrester comprising a glass envelope containing an ionizable gas, a pair of line electrodes and a ground electrode in the envelope, and a glass post' connected to the envelope and projecting into its interior, said post having a stem portion lying between at least two of the electrodes, and an enlarged head portion lying between portions of the line electrodes and a portion of the ground electrode.

7. A lightning arrester comprising a glass envelope containing an ionizable gas, a pair of line electrodes and a ground electrode in the envelope, and a glass post connected to the envelope and comprising a stem portion extending through the discharge space between the line electrodes and Whose transverse dimension is less than that of the line electrodes so that the stem portion does not form a complete obstruction between the line electrodes, and an enlarged head portion at the distal end of the stem portion lying between portions of the line electrodes and a portion of the ground electrode.

8. A double-end lightning arrester comprising a glass envelope containing an ionizable gas, a pair of spaced line electrodes supported at one end of the envelope, lead-in wires extending into the envelope through the said end thereof and electrically connected to the line electrodes, a ground electrode spaced from the distal ends of the line electrodes longitudinally of the envelope, at least one lead-in wire extending into the envelope through its other end and electrically connected to the ground electrode, and a glass post integral with the envelope at that end which contains the line electrodes, said post having a stem portion which extends longitudinally of the envelope through the space between the line electrodes and having a head portion which is radially enlarged to provide portions lying between said distal ends of the line electrodes and the adjacent portion of the ground electrode.

9. A lightning arrester comprising a glass envelope containing an ionizable gas, a glass post integral with the envelope and projecting into its interior, two line electrodes and a ground electrode grouped about the axis of said post, said post having a radially enlarged head portion lying between the electrodes so that contact between said head portion and the electrodes will prevent contact between the electrodes themselves in the event of their displacement toward the axis of the post.

10. A lightning arrester comprising a glass envelope containing an ionizable gas, a pair of line electrodes supported at one end of the envelope in spaced relation transversely of the envelope, a ground electrode supported at the other end of the envelope with its distal end spaced from the distal ends of the line electrodes longitudinally of the envelope, and a glass post integral with the envelope at that end of the envelope which contains the line electrodes and extending through the space between the line electrodes, the transverse dimension of the glass post being less than that of the line electrodes and the post having an end portion extending beyond the distal ends of the line electrodes adapted to prevent contact between the distal ends of the line electrodes and the distal end of the ground electrode.

JOHN A. BIGWOOD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,034,584 Chapman Aug. 6, 1912 1,104,961 Chapman et al. July 28, 1914 1,680,518 Holden Aug. 14, 1928 1,995,737 Everett Mar. 26, 1935 2,072,733 Dobke Mar. 2, 1937 2,117,794 Duinker et al May 17. 1938 2,121,333 Barclay June 2l, 1938

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