US3238330A - Open type cutout with v-shaped mounting bracket for a pair of flexible insulating arms having a resilient insulating coating - Google Patents

Description

March 1, 1966 R s fl- JR 238,330

3, OPEN TYPE CUTOUT WITH V-SHAPED MOUNTING BRACKET FOR A PAIR OF FLEXIBLE INSULATING ARMS HAVING A RESILIENT INSULATING COATING Filed May 31, 1962 [iii 67276 jaz/n k 527% 2;

United States Patent York Filed May 31, 1962, Ser. No. 198,888 2 Claims. (Cl. 200-114) This invention relates to open type cutouts and more particularly to a new form of open type cutout of simplified construction.

In the cutout field, the open type cutout usually employs a single rigid insulator, usually of porcelain. An example of this type of open cutout is disclosed in Patent No. 2,821,568, granted January 28, 1958 in the name of the present inventor and assigned to the same assignee as this invention. In these open type cutouts, the insulator is usually mounted at its mid point by a mounting bracket secured to a supporting structure, such as for example the arm of an electric pole. Terminals are usually provided on the upper and lower end of the supporting insulator, generally as part of stationary contacts. A fuse holder containing a fusible link is connected between these stationary contacts. In these cutouts, the blowing of the fuse places a large force on both the insulator and the mounting bracket through the stationary contacts. These forces have a deleterious effect on both the insulator and the mounting bracket and, over a period of time, with the blowing of the fuses of the cutout, these structures become weakened, or ruptured, eventually requiring the the replacement of the cutout. Of course it will be understood that where the cutout operates to relieve high currents, the brittle, frangible porcelain insulator may break due to the shock of the cantilever force. If the porcelain survives this shock, the force is passed to the mounting bracket, which may fail. A failure of this nature may occur the very first time the cutout operates.

A well known problem, due to the frangible nature of the porcelain insulator is the breakage which often occurs in handling. They are also subject to damage during installation and while being transported, both in shipment and on line trucks. Of course, the damage due to thrown stones and rifle shots are well known. Obviously, it is desirable to minimize or eliminate this problem.

Further, due to the differences in the electrical potential between the mounting bracket and the stationary contacts and terminals of the cutout, it is necessary to provide a sufliciently long insulator to prevent flashover from the terminals to the mounting bracket. As will be understood, contamination and water increase the hazard of flashover, generally requiring an increased length of the insulator. However, due to problems of height in mounting the cutouts, and the problems of the weight of the insulator and the cost of the cutout, it is generally desirable to decrease the size and weight of the insulator. Obviously, these problems are the antithesis of each other and it is difficult to provide a solution for one problem without aggravating another problem.

It is therefore a principal object of this invention to provide a new and improved open type cutout having improved insulating characteristics.

A further object of this invention is to provide a new and improved open type cutout which will substantially lessen or eliminate the strain on the mounting bracket when the fuse blows.

A still further object of this invention is to provide a new and improved open cutout without use of a rigid insulator.

Another object of this invention is to provide a new and improved open cutout which is smaller and lighter in weight than previous cutouts and which may be manufactured at lower cost.

Still another object of this invention is to provide a new and improved open cutout which will not be subject to breakage during handling, shipping and the like.

In carrying out this invention in one form, an open type cutout is provided comprising a pair of flexible insulating arms formed of plastic rod covered with a resilient insulating coating. The flexible arms are secured at one end to a mounting bracket and at the other end of each arm, stationary contacts for a fuse are provided. A fuse tube with a fuse link is connected between the stationary contacts to form an open type cutout. The blowing of the fuse will cause the resilient arms to flex or bend, thus absorbing the forces of the fuse blowing, and preventing stresses from being transmitted to the mounting bracket.

The invention which is sought to be protected will be particularly pointed out and distinctly claimed in the claims appended hereto. However, it is believed that this invention and the manner in which its various objects and advantages are obtained, as Well as other objects and advantages thereof, will be better understood from the following detailed description of a preferred embodiment thereof, when considered in the light of the accompanying drawing in which:

FIGURE 1 is a side elevation of a new and improved open cutout according to the preferred embodiment of the invention;

FIGURE 2 is a longitudinal sectional view of one arm of the cutout taken on the lines 22 of FIG. 1; and

FIGURE 3 is a cross sectional view of one arm of the cutout taken on the line 3-3 of FIG. 1.

Reference will now be made to the drawings, in which like numerals are used to indicate like parts throughout the various views thereof. Referring first to FIG. 1, showing the present preferred embodiment of this invention, it can be seen that the improved open cutout, generally designated as 10, comprises a pair of elongated, resilient arms 12 and 14. As shown, arms 12 and 14 are secured to a mounting bracket 16 which in turn is adapted to be secured to a support member 18 for mounting of the cutout. On the opposite end of the arms 12 and 14 the stationary contacts for the cutout are provided. As indicated on the arm 12 the stationary contact 20 is provided, while on the arm 14 the stationary contact 22 is provided. A fuse tube 24 enclosing a fusible element, indicated at 26, is connected between the upper stationary contact 20 and the lower stationary contact 22 to form an open cutout.

The various constructional details of the upper stationary contact 20 and the lower contact 22 may be of conventional construction and form no part of the invention herein. As indicated, the upper contact 20 is provided with a latching means cooperating with the latch 28 on the fuse 24, while the lower contact 22 is provided with a pivot bearing cooperating with the trunnion 30 on the lower end of fuse tube 24 for pivotally mounting fuse tube 24 in a manner well understood by those skilled in the art. Terminals 32 and 34 are provided on the upper and lower contacts 20 and 22, respectively, and are connected to the desired electrical service lines in a manner well understood by those skilled in the art.

As will be apparent from the above description, the cutout is provided with a pair of resilient arms such that when the fuse blows the resilient arms will be bent or flexed from the forces of the fuse blowing, thus preventing any stresses from being transmitted to the mounting bracket 16. Inasmuch as each of the resilient arms 12 and 14 is formed of a resilient plastic material, as will be more fully described, there is no rigid insulator to be weakened or ruptured by the strain of the blowing fuse.

Referring now to FIGS. 2 and 3 of the drawing, it can be seen that each of the insulator arms 12 and 14 is formed of a central plastic rod 36, the rod being coated with a resilient plastic material 38. The plastic rod 36 may be any well known insulating plastic material which is sufliciently resilient and strong enough to absorb the shock of the blowing of the fuse 26 in the fuse holder 24. Preferably, the plastic rod 36 will be reinforced with some type of fiber to increase its strength. The plastic coating material 12 is preferably one of the insulating plastic materials which does not form carbon tracks when subjected to either creepage discharges or flashover, such as for example, the materials disclosedin Patents 2,997,526, 2,997,527, and 2,997,528 which are assigned to the same assignee as the present invention. It should be understood that while the preferred plastic coating is insulation material such as described in the aforementioned patents, that other types of plastic coating, such as butyl rubber coatings may be provided if desired.

As shown, particularly in FIG. 2, the plastic coating 38 is formed on the plastic rod 36 leaving the ends of the rod uncoated. The ends of the rods are then inserted into the mounting bracket 16 and either of the stationary contacts 20 or 22. The rods are secured thereto by a resin material which will firmly connect the plastic rod to the mounting bracket 16 and to one of the terminals 20 or 22. In order to increase the voltage required to flashover between the terminal 20 and the mounting bracket 16 over the arm 12, particularly under wet conditions, the insulating coating 38 is formed with a number of ridges or petticoats 40, as indicated. As is well understood, by means of the petticoats 40 the creepage distance and wet flashover voltage between the stationary terminal 20 and the mounting bracket 16 is increased.

In the preferred form of the invention, as shown specifically in FIG. 1, the mounting bracket 16 is formed in a V-shape and is provided with cylindrical connecting members 42 and 44 which are formed integral with the mounting bracket 16 for receiving each of the arms 12 and 14 respectively. Thus the arms 12 and 14 form a V-shaped cutout insulator in the manner shown in FIG. 1. The stationary contacts 20 and 22 are also provided with cylindrically formed end portions for receiving the op posite ends of the arms 12 and 14, respectively, in the manner more particularly shown in FIG. 2 of the drawing.

Of course it will be understood that while the preferred embodiment is as set forth above, it is not necessary that the cylindrical connecting members be provided since, obviously, the insulating arms 12 and 14 may be connected to both the mounting bracket 16 and the stationary contacts 20 and 22 in any number of ways which are well understood by those skilled in the art. For example, the plastic rods 36 could be provided with flattened ends and bolted to the mounting bracket-and stationary contacts. However, from the abovedetailed description of the preferred embodiment of this invention, it will be apparent that the insulating arms 12 and 14, which are substantially identical to each other, may be manufactured on a production line basis at extremely low cost when compared to the cost of the porcelain type insulator which they are designed to replace. Further, the mounting brackets 16 and the stationary contacts 20 and 22 also may be manufactured relatively inexpensively on a production line basis. Thus it can be seen, that by means of the open cutout specifically disclosed in this invention that a resilient cutout may be provided for relatively low cost which will provide an increase in the flashover voltage between the stationary contactsand the mounting bracket, and which will absorb any of the forces due to the blowing of the fuse without transmitting such forces to the mount bracket. Thus it can be seen that by means of this invention, there is provided a simplified, low cost open cutout, provided with resilient arms which do away with the need of a rigid insulator and which will prevent the forces due to blowing from rupturing the mounting bracket of the cutout or the insulating structure. Further, due to the elimination of the heavy porcelain insulator the weight of the cutout may be substantially reduced. For example, in comparing an older type 15 kv. cutout with a 15 kv. cutout formed according to this invention, the weight has been reduced substantially in half without sacrificing any of its electrical properties. Also, it will be clear that the novel cutout of this invent-ion substantially eliminates the breakage problem by eliminating the frangible porcelain insulator.

While there has been shown and described the present preferred embodiment of the invention, it will be well understood by those skilled in the art that various changes may be made in the construction and form of the cutout without departing from the spirit and scope of the invention. Therefore, it is to be understood that the invention is not to be limited by the foregoing detailed description but it includes all changes and modifications as fall within the scope of the invention as defined in the appended claims.

What is claimed as new and which it is desired to secure by Letters Patent of the United States is:

1. An open type cutout comprising, in combination: a substantially V-shaped mounting bracket for mounting the cutout to a support, the sides of said V-shaped bracket having connecting means, a pair of flexible insulating arms formed of plastic rod covered with a resilient insulating coating, one end of each of said pair of flexible arms secured to said connecting means on each side of said V-shaped mounting bracket, a stationary contact secured to the other end of each of said pair of flexible arms, and terminal means provided on each of said stationary contacts.

2. An open type cutout comprising, in combinationz a substantially V-shaped mounting bracket having connecting members formed integrally therewith on each side of said V shaped bracket, a pair of flexible insulating arms formed of plastic rod covered with a resilient insulating coating, one end of each of said pair of flexible arms being secured in one of said connecting members of said V-shaped mounting bracket, a stationary contact secured to the other end of each of said pair of flexible arm-s, terminal means provided on each of said stationary contacts, a fuse tube including a fuse link connected between said stationary contacts whereby blowing of said fuse link will cause said resilient arms to flex, thus absorbing the forces of the fuse link blowing and preventing stresses from being transmitted to said mounting bracket.

References Cited by the Examiner UNITED STATES PATENTS 1,818,456 8/1931 Bowie 200-48 2,179,749 11/1939 McCluskey et al. 200114 2,727,961 12/1955 Smith 200 X 2,732,423 1/ 1956 Morrison 174-440 X 2,961,518 11/1960 Hermann 200-114 2,986,619 5/1961 McCloud 200114 BERNARD A. GILHEANY, Primary Examiner.

ROBERT. K. SCHAEFER, Examiner.

T. A. ROBINSON, H. A. LEWITTER,

Assistant Examiners.

Claims (1)

1. AN OPEN TYPE CUTOUT COMPRISING, IN COMBINATION: A SUBSTANTIALLY V-SHAPED MOUNTING BRACKET FOR MOUNTING THE CUTOUT TO A SUPPORT, THE SIDES OF SAID V-SHAPED BRACKET HAVING CONNECTING MEANS, A PAIR OF FLEXIBLE INSULATING ARMS FORMED OF PLASTIC ROD COVERED WITH A RESILIENT INSULATING COATING, ONE END OF EACH OF SAID PAIR OF FLEXIBLE ARMS SECURED TO SAID CONNECTING MEANS ON EACH SIDE OF SAID V-SHAPED MOUNTING BRACKET, A STATIONARY CONTACT SECURED TO THE OTHER END OF EACH OF SAID PAIR OF FLEXIBLE ARMS, AND TERMINALS MEANS PROVIDED ON EACH OF SAID STATIONARY CONTACTS.

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