US2650330A - Lightning arrester - Google Patents

Description

Sheefs-Sheet 1 H. O. STOELTING LIGHTNING ARRESTER Aug. 25, 1953 Filed April 13, 195o Aug. 25, 1953 H. o. sTol-:LTING LIGHTNING ARRESTER 2 Sheets-Sheet 2 Filed April 13', 1950 Patented Aug. 25, 1953 LIGHTNING ARRESTER Herman O. Stoelting, Milwaukee, Wis., assignor to McGraw Electric Co., Milwaukee, Wis., a corporation of Delaware Application April 13, 1950, Serial No. 155,579

1 Claim. l

This invention relates to lightning arresters.

In lightning arresters, particularly those of the -disk type where valve material in the form of a flat plate is employed, considerable difficulty has' been experienced due to the fact that dash-overs around the valve material frequently occur. The effect of these flash-overs is, therefore, to short out the valve material and to provide a conducting path which bridges or shunts the valve material. In lightning arresters of this general type the valve material is in a compacted form and is relatively thin, usually in the form of a disk. There is, therefore, not very much physical space between the two conducting plates on opposite sides of the valve material and though this space is greater than the spark gap in series with the valve material, nevertheless under severe conditions, flash-overs around the valve material occur, thereby rendering the valve material ineffective.

This invention is designed to overcome the above noted defects and objects of this invention are to provide lightning arresters which are so made that they prevent dash-overs around the valve material and thus insure the valve material acting in its desired capacity.

Further objects are to provide a construction which is very simple and which can be readily applied to existing types of lightning arresters without any alteration of the structure of the arrester itself.

Embodiments of the invention are shown in the accompanying drawings, in which- Figure 1 is a sectional view through a disk type valve arrester with means provided for substantially preventing flash-overs.

Figure 2 is a bottom View of the lightning ar rester, such view corresponding to the line 2 2 of Figure 1.

Figure 3 is a sectional view on the line 3-3 of Figure 1.

Figure 4 is a perspective view of the valve material with the felt barrier secured thereto.

Figure 5 is a View corresponding to Figure 1 showing a further form of the invention.

Figure 6 is a fragmentary sectional view on the line 6-6 of Figure 5.

Figure '7 is a perspective View of the valve material with the felt barrier thereon, such View being taken from the left-hand side of Figure 6.

Figure 8 is a View correspon-ding to Figure '7 taken from the opposite side thereof, that is to say, from the right-hand side of Figure 6.

Referring to Figures 1 to 4, it will be seen that the lightning arrester comprises an insulating base l and an insulating housing 2, which are detachably secured together by means of screws 3. These screws additionally serve to assist in anchoring or securing the terminal plates 4 and 5. Further than this, screws 6, t extend through extensions of the terminal plates 4 and 5 and secure the spring metal clips 'I and 8, see Figure 3, in place. These spring metal clips are adapted to have the lightning arrester properly mounted therebetween and held by the resiliency of the clips.

The lightning arrester assembly comprises a disk 9 of Valve material, such for instance as silicon carbide, which is provided on opposite sides with metal plates I0 and Il. The metal plates l0 and II have outwardly projecting portions l2 and I3. The outwardly projecting portion i2 is Vdetachably received within an aperture I4 formed in the clip 8, see Figure 3. The outwardly projecting portion I3 is seated within a recess l5 formed in a porcelain insulating block or spacer I6.

The spring clip 'I bears against a metal plate Il which is provided with a plurality of inwardly turned prongs or fingers I8 adjacent its upper portion, as shown in Figures 1 and 3. The prongs or fingers I8 are spaced a predetermined distance from the metal plate Il. In view of the fact that the tolerance allowed t-he porcelain spacer I6 is relatively large in comparison to the accurate spacing required between the prongs I8 and the plate Il, an insulating plastic washer or spacer I9 is provided, directly between the plate l1 and the porcelain I6.

Any suitable means may be provided for temporarily xing the position of the porcelain spacer I6 and the plate Il. For instance, the plate l'l may be provided with outwardly turned ears 20 Which t within a suitable aperture 2| formed in the clip '1. Also the plate l'i may be provided with inwardly pressed portions which t Within corresponding apertures or depressions formed in the porcelain plate I6 and indicated by the reference character 22.

In lightning arresters of this type it has been found that most of the flash-overs occur around the top portion of the valve material 9. Nearly all of these flash-overs can be prevented by providing a felt or similar barrier 23 which may be attached to the valve material 9 or may be simply positioned against the valve material. At all events, this felt barrier 23 is held in place by the cover or housing 2, as is obvious from an inspection of Figures l and 3. The material forming the barrier actually used is a form of felt,

3 although it is to be understood that any other suitable yielding material of an insulating nature may be employed, so that it will seal between the valve material disk 9 and the housing 2.

The construction, thus far described, prevents nearly all of the hash-overs. However, to insure complete protection against ash-overs, the construction illustrated in Figures 5 through 8 is employed. In this form of the invention, substantially the same general arrangement of the parts is employed. However, the disk of valve material is indicated by the reference character 24 and is completely surrounded by a felt member indicated generally by the reference character 25. This felt member has a relatively wide upper portion 2S which has a narrow lower portion 21 which may be split, if desired, as indicated at 28. 'Ihe felt member or barrier 25 is provided with a pair of downwardly projecting, tapered legs 29 which nt between the upwardly extending support 30 for the disk 24 cf the valve material and the adjacent wall of the housing 2, see Figure 5.

In the form of the invention shown in Figure 1, the support 39 merely acts as a support for the disk 9 of valve material. However, in the form of the invention shown in Figures 5 through 8 the support 30 not only acts as a support for the valve material, butI also acts as a part of the total barrier for preventing flash-over around any portion of the disk 24.

It is to be noted that the reduced or narrowed portion 21 of the felt barrier 25 bears against the right-hand side, as viewed in Figure 6, of the support 30, the integral support 3U being formed with the base portion I.

In the last described form of the invention, the felt forms a complete barrier extending all the way around the disk 24 and thus effectively prevents flash-overs around any marginal portion of the disk.

It will'be seen that this invention provides an effective means for preventing flash-over around the marginal portion of the disk of valve material and connes the conducting vapors formed by an arc striking at the spark gap from passing around the marginal portion of the disk of valve material and thereby prevents the formation of a conducting path around the disk.

It is to be noted that the plastic Washer, combined with the ceramic spacer, enables the accurate spacing of the spark gap electrodes to be obtained. The ceramic spacer varies in thickness due to errors occurring in its manufacture, but the thin plastic washer enables the exact tolerance desired to be obtained.

It will be seen further that the invention may be very readily applied to existing types of lightning arresters without any change in the structure of the arrester itself, other than adding the felt barrier hereinabove described.

` Although this invention has been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim:

A lightning arrester comprising a housing, a pair of terminals carried by said housing, a pair of spring clips mounted within said housing and connected to said terminals, and a lighting arrester assembly mounted between said spring clips and consisting of a disk of valve material having a conducting plate on one side thereof, a second conducting plate spaced from said rst conducting plate and forming therewith a spark gap, an insulating spacer of ceramic material interposed between said plates, and a tolerance adjusting plastic washer interposed between said ceramic material and one of said plates, said insulating spacer being relatively thick and said plastic washer being relatively thin.

HERMAN 0. STOELTING.

References Cited in the file 0f this patent UNITED STATES PATENTS Number Name Date 1,923,943 McFarlin Aug. 22, 1933 1,935,810 McFarlin Nov. 21, 1933 2,242,838 Somes May 20, 1941 2,297,323 Rees Sept. 29, 1942 2,305,398 Watson Dec. 15, 1942 2,415,945 Gilson Feb. 18, 1947 OTHER REFERENCES MacCarthy, Abstract of application Serial No. 571,799 published July 12, 1949, 624 O. G. 636.

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