US1926871A - Fused grading shield - Google Patents

Description

Sept? 1933- K. A. HAWLEY 1,926,871

FUSED GRADING SHIELD Filed Dec. 23, 1929 2 Sheets-Sheet 1 L Jnvenkw 2 Ken? 14. HQdi// Straw/Yum Sept. 12, 1933. HAwLEY 1,926,871

FUSED GRADING SHIELD Filed Dec. 23, 1929 2 Sheets-Sheet 2 QCIEI Patented Sept. 1 2, 1933 PATENT OFFICE 1,926,871 FUSED GRADING SHIELD Kent A. Hawley, Baltimore, M(l., assignor to Locke Insulator Corporation, Baltimore, Md., a corporation of Maryland Application December 23, 1929 Serial No. 416,115

5 Claims.

The invention relates to protective devices for use in connection with high tension transmission lines for the purpose of protecting strings of insulators against damage resulting from arcing or flashing over of lightning impulses such as may occur during thunderstorms.

It is well known that numerous patents have been granted covering the employment of electrodes of one sort or another at the ends of a string or chain of insulators used to suspend a conductor from a grounded support. Very frequently these electrodes take the form of horns at the top of the-string and either horns or a ring at the lower end of the string. Certain modifications and adaptations of the principle involved have also been provided in conjunction with installations wherein the conductor is mounted above a grounded support by means of pin, post or pedestal type insulators which are well known in the art. It has also been proposed to provide means in the nature of a fire extinguishing material for extinguishing the arc, or an explosive ignited upon the occurrence of an are for diverting the same from the insulators so that it will not continue for a sufficient length of time to cause any damage. However, known devices for this purpose are comparatively crude and possess numerous disadvantages, some of which are a mere matter of mounting or mechanical construction and another of which is that there is insufficient means to take care of a succession of flash-overs.

It is with the above facts in view that I have devised the present invention which has for its general object the improvement of devices of this class and which has for an important object the provision of an arrangement wherein there is a plurality of fuses, preferably of the mechanical expulsion type, adapted to come into play one at a time or in sequence at different times so that protection will be afforded against more than a single flash-over.

A more specific object of the invention is to provide a protective device embodying a sectional grading ring in which each section is equipped with a fuse.

A still further objectis' to provide a protective device embodying a novel means for supporting the fuses from the grading ring, the arrangement being moreover such that burned out or exhausted fuses may be readily replaced by new ones.

Another specific object is to provide a protective apparatus which has a single point suspension with respect to the string of insulators and which may therefore. be very readily installed without providing a multiplicity of attachment devices.

An additional object is to provide a device of this character which will be simple and inexpensive to make, easy to use, positive in action, efficient and durable in service, and a general improvement in the art.

To the attainment of the foregoing and other objects and advantages, the invention preferably consists in the details of construction and the arrangement and combination of parts to be hereinafter more fully described and claimed, and Llustrated in the accompanying drawings in which:

Figure 1 is a side elevation of a string of suspension insulators equipped with my invention and showing one form thereof,

Figure 2 is a section taken on the line 2-2 of Figure 1,

Figure 3 is a side elevation showing a grading ring at the lower end of theinsulator string provided with a plurality of fuses, and

Figure 4 is a top plan view thereof.

Referring more particularly to the drawings the letter A designates a string of suspension insu- $0 lators of any ordinary or preferred type connected by any of the usual means for the purpose. At the upper end of the string is a suspension element B by means of which it may be suspended from a tower or other support, and the string is intended to carry, at its lower end, a suspension element C to which is connected a clamp D supporting the conductor E. At the upper end of the string is an arcing horn device F of any ordinary or preferred type.

In carrying out the form of the invention disclosed in Figures 1 and 2, I provide a grading ring 10 which is here shown as carried by insulators 11 mounted on arms 12 of angular form which have their inner ends secured to a suspension member 13 interposed between the lowermost insulator unit and the suspension element C for the clamp D. The member 13 necessarily conforms to the type of connection with which the insulator units are equipped, it being well known that some are of the clevis type whereas others are adapted to be connected together in string or chain formation by ball and socket members.

Each insulator 11 is provided at itsupper end with an angle bracket 14 bolted at 15 to the grading ring and fastened by a bolt 16 to a metallic insert 17 embedded and secured within the insulator. At their lower ends the insulators are secured to the arms 12 by bolts 18 screwed into inserts 19 anchored Within the insulators. By this arrangement it will be seen that the grading ring is insulated with respect to the clamp and conductor.

The protective means in this instance comprises a fuse 20 which has one end electrically connected with the grading ring 10 and its other end in electrical connection with the conductor through the elements C, 13, 12 and 18. The fuse may be of any ordinary construction suitable for the purpose but is preferably of the expulsion type well known in the art. Details are not given here as they are rather immaterial to the present invention. However, a fuse of this type does include an outer member of insulating material within which are metallic elements connected with terminal ferrules 21. To mount this fuse so that it will function properly I provide angular brackets 22 one of which is mounted at the lower end of one insulator and the other at the upper end of the other, these brackets being held by the bolts 18 and 16 respectively. Spring clips 23 are mounted on these angular brackets and the metal ferrules of the fuse are snappingly engageable therein and held by spring tension. It will be noted that when the fuse is in applied position it extends diagonally and that its upper or active end will, upon the occurrence of an arc, divert the same away from the string.

In the operation it will be seen that as the fuse is in series between the conductor and the air gap between the grading ring and the arcing horns F when a flash-over occurs as the result of a suddensurge along the line, this excess current will not only jump the gap but must flow through the fuse, melting away the fusible element forming a part thereof as disclosed in said co-pending application. In fuses of this type the internal parts are thrown out by spring pressure and the arc across the gap will consequently be diverted and extinguished.

In Figures 3 and 4 I have illustrated a modification which possesses advantages over what has been described above. Referring to these flgures in detail, I have provided a grading ring formed of two similar sections 10 between the ends of which are interposed and mounted in any suitable manner insulators 24. The sections of the ring are bolted to angle brackets 25 secured in any desired manner, such as that above described, to the upper ends of the insulators 11 which have their lower ends secured to the arms 12 as described in connection with the first form of the invention. Each bracket 25 is here shown as carrying a clip 26. Secured at the lower ends of the insulators are brackets 27 corresponding to the brackets 22 and equipped with clips 28. In this instance, as I provide two ring sections I make use of two of the fuses 20 which have their terminal ferrules 21 engaged within the opposite clips 28 and 26 respectively. By this arrangement it is apparent that the fuses are diagonally disposed or inclined with respect to v the vertical and also with respect to each other.

each fuse having one end in electrical connection with the conductor and the other in electrical connection with the grading ring so as to be in series with the air gap between the ring and arcing horns. In this form the operation is exactly the same as that of the first described form, the only difference being that as there are two fuses there is ample protection against two flash-overs as only one fuse will be blown at one time.

From the foregoing description and a study of the drawings it will be apparent that I have thus provided a simply constructed and inexpensive arrangement for protecting insulator strings against damage in the event of flash-over, and consequently avoiding service interruption. After an electrical storm or other unusual condition which might result in flash-overs, it is a simple matter for an inspection crew to ascertain what fuses have been blown and to replace those that have been so that everything will be all set in preparation for a future emergency. It is believed that the construction, operation and advantages will be readily apparent to one skilled in the art without further explanation.

While I have shown and described the preferred embodiment of the invention, it should be understood that the disclosure is merely an exemplification of the principles involved as the right is reserved to make all such changes in the details of construction as will widen the field of utility and increase the adaptability of the device provided such changes constitute no departure from the spirit of the invention or the scope of the claims hereunto appended.

Having thus described the invention, I claim:

1. A protective device for a string of suspension insulators carried by a grounded support and carrying a conductor, comprising arcing horns at the upper end of the string, a grading ring at the lower end of the string, arms at the lower end of the string and in electrical connection with the conductor, insulators mounted upon said arms and supporting said grading ring, and a fuse carried by said insulators and having one end in electrical connection with the conductor through one of said arms and having its other end in electrical connection with the ring to be in series with the gap between the ground and the conductor.

2. A protective device for a string of suspension insulators suspended from a grounded sup- 115 port and carrying a conductor, comprising an electrode at the upper end of the string connected with the ground, a grading ring at the lower end of the string, metallic arms at the lower end of the string, insulators mounted on said arms and carrying said grading ring, and a fuse having one end mounted at the bottom of one insulator and its other end mounted at the top of the other insulator, said fuse constituting the sole electrical connection between the con- 125 ductor and the ring and being in series with the air gap between the ring and the electrode.

3. A protective device for a string of suspension insulators, the insulators depending from a grounded support andcarrying a conductor, 180 comprising arcing horns at the upper end of the string, a grading ring at the lower end of the string formed of sections with insulators interposed therebetween, means for supporting said sections and insulating the same from the conductor, and a plurality of fuses electrically connected at one end with the conductor and electrically connected at their other ends with the respective ring sections, said fuses being in series with the air gap between the respective ring sections and the arcing horns.

4. A protective device for a string of suspension insulators carried by a grounded support and carrying a metallic conductor support, com prising an electrode at the upper end of the string, supporting members at the lower end of the string in electrical connection with the conductor, insulators mounted upon said last named supporting members, an electrode carried 150 by said second named insulators and located at ioo by said metallic element, insulators mounted on said support, a grading ring surrounding the string and mounted upon said insulators, clips at the upper and lower ends of said last named insulators, and expulsion fuses having terminal ferrules engaged within said clips, said fuses being in electrical connection at one end with the conductor and at the other end with the grading ring and being in series with the gap between the arcing horns and the conductor.

IGINT A. HAWLEY.

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