US2756367A - Heavy duty arrester - Google Patents

Description

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HEAVY DUTY ARRESTER Filed Sept. 13, 1952 INVENTOR.

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United States Patent HEAVY DUTY ARRESTER John S. Baker, Skokie, Ill., assignor to Cook Electric Company, Chicago, Ill., a corporation of Illinois Application September 13, 1952, Serial No. 309,483

3 Claims. (Cl. 317-66) This invention relates to arresters, and more particularly to heavy duty arresters in telephone and similar communication circuits.

It has been found expedient in many instances to carry telephone circuits on the same poles carrying power circuits of considerably higher voltage and usually at a location lower than the power lines, but at such close proximity that there are occasions when contact between the two occurs. It is essential to remove the power voltage from the telephone line as promptlyas possible before any damage is done to a subscribers premises or person or to the telephone company personnel.

It is an object of this invention to provide a high capacity arrester providing a path to ground of sufficiently low impedance so that the fault current iflowing through the arrester will quickly rise to a suificiently high value to trip the circuit breakers in the power line. If the power breakers deliver an inverse time element -break,.-i't is nece sary for the arrester to carry theheavy fault current during the time required for the breakers to tip. Generally, the arrester will carry the fault current until the line is cleared by the circuit breaker in the power line. If the arrester should by chance be damaged or destroyed, it will prevent, however, damage arising from high voltage on the telephone circuits, and, therefore, serve its purpose, but, on the other hand, the high capacity arrester will also provide lightning protection when suitably spaced along the exposed line.

A further object of the invention is to provide an arrester structure of this type which is simple, inexpensive to make, and efiicient in operation.

Other objects and advantages of the invention will be apparent from the following detail description when taken in connection with the accompanying drawing which forms a part hereof.

In the drawing:

Figure 1 is a schematic layout illustrating the installation of several arrester units embodying the invention on a pole carrying the usual high voltage power lines;

Fig. 2 is a perspective view of an arrester unit with the cover removed;

Fig. 3 is an enlarged vertical cross section of the arrester; and

Fig. 4 is a top view of the arrester with the cover removed.

Referring to the drawings, the arrester may comprise a bracket 1 of any shape suitable to mount the arrester in the location desired. Upon platform 2 of bracket 1 is mounted a porcelain base 3 secured in position by bolts 4 projecting at their lower ends through this platform 2. The upper face 5 is preferably formed with a number of raised seats 6 for carrying carbon electrods 7, 8 and 9, each of these electrodes being secured in position by posts 10 that preferably pass through each electrode.

Electrodes 7, 3 and 9 are preferably spaced from each other as illustrated in Fig. 4 to provide therebetween spark gaps 11, 12 and 13. Posts 10 preferably project through porcelain base 3 and are held in position by terminal clips -14 to which line wires 15 and 16 as well as ground wire 17 are secured as by soldering or the like. To provide simplicity and compactness, the underside of porcelain base base 3 is preferably recessed at 18 and posts 10 terminate therein. This provides a compact arrangement which disposes the wiring connections within porcelain base 3 and out of the way of the upper portion which carries the electrodes 7, 8 and 9. Mounting bolts 4 are seated in recesses 19 formed in porcelain base 3 so that the heads of these bolts are disposed below the upper face 5. The threaded portion of the bolts passes through openings 20 in platform 2 of bracket 1 and holds the porcelain base 3 secure on the bracket by clamping nuts 21. Hence, it will be observed that porcelain base 3 may be easily removed from bracket 1, the only operation being the removal of the lower clamping nuts 21 in order to gain access to recess 18. A cover 22 snugly fitting over porcelain base 3 and seating on platform 2 of bracket 1 suitably encloses the electrodes and the porcelain base.

The upper part of each electrode is reduced at 24 and formed with a sloping face 25 upon which is seated a collar 26, preferably a low melting point alloy. It will be observed in Fig. 3 that the direction of slope of face 25 on any one electrode is toward the other two electrodes. Each electrode is provided with a washer 27 against which the head of each post 10 abuts to clamp the electrode firmly upon seat 6 when its terminal clip 14 is pulled up tightly upon the lower threaded end of the post.

In Fig. l, the arrester units are shown connected in the telephone lines .30 and 31 and mounted on the cross arm 32, which may be, and are often, disposed below the power lines 33. The wires 15 and 16 are shown leading from the arrester units and connected to the telephone lines 30 and 31. The ground wire 17 is led from each arrester unit along cross bar 32 and is connected to a suit- .able ground by a clamp 34. The manner in which this ground connection is established is immaterial.

It is quite apparent from Fig. 1 that due to the close proximity of telephone lines 30 and 31 with power lines 33, there will be occasions when contact occurs between the two. It is then essential to remove the power voltage from the telephone lines 30 and 31, and, as previously stated, this must be done as promptly as possible to prevent damage to the subscribers premises or person or to telephone company personnel.

The arrester units herein described provide low impedance paths to ground so that the fault currents flowing through the arrester units will quickly rise to a sufficiently high value to trip circuit breakers (not shown) in power line 33. It is also to be remembered that if the power breakers deliver an inverse time element break, it is necessary for the arresters to carry the heavy fault currents during the time required for the circuit beakers to trip.

To establish the ground at the arrester units when fault currents appear so that the arrester units may carry the same until the circuit breakers in the power lines trip, one or more collars 26 of low melting point alloy will fuse, and, due to the faces 25 in the electrodes 7, 8 and 9 sloping in the direction of each other and the spark gaps 11, 12 and 13 formed by the spacing of these electrodes, the fused alloy will bridge these gaps and ground electrodes 8 and 9 to electrode 7 connected by wire 17 to ground connection 34.

It will be apparent, however, that fault currents of momentary duration will ground through electrode 7 without necessarily fusing collars 26, and, consequently, these collars will not always require replacement. If they do need replacement as the result of fusing, access thereto may be readily had by removing cover 22. If one or more of these collars 26 fuse and the fused alloy bridges either or both gaps 11 and 12, a low impedance path to ground is immediately established so as to cause the fault currents to 3 rise to a sufficiently high value to efiect tripping of the power breakers.

Where, however, a high voltage, high capacity power lead comes into contact with the low voltage circuit, a violent surge of current will flow from the high voltage line into the low voltage line and will find a ready path to ground at the electrodes 7, 8 and 9 of the arrester. As the resistance from the power house to the ground lowers, the fault current will increase and will more quickly operate the circuit breaker at the power station to remove the hazard from the low voltage circuit. Under such circumstances, the heat generated by the arcing between electrodes will fuse the fusible collars 26. This fusible material 26 will enter the region between the discharging electrodes 7, S and 9, thereby lowering the resistance still further and hastening the operation of the circuit breaker. As the fusible In terial 26 enters the region of the arc, it may or may not be vaporized by the heat and blown clear of the gap and the electrodes. Thus, when the power breakers open and clear the fault, the arrester may not be permanently short-circuited, but may remain in operating condition lacking only the fusible collars 26. When convenient, fusible collars 26 can be replaced by the service company because the arrester is in such operating condition as to allow the low voltage circuit to function normally and to be adequatly protected.

From the foregoing description it will be observed that a very simple and effective heavy duty arrester unit is provided and may be advantageously used in telephone lines carried on cross arms on poles carrying power lines above to protect the telephone lines in the event of accidental contact with the power lines and at the same time provide desirable lighting protection.

Without further elaboration, the foregoing will so fully explain the gist of my invention that others may, by applying current knowledge, readily adapt the same for use under varying conditions of service, without eliminating certain features, which may properly be said to constitute the essential items of novelty involved, which items are intended to be defined and secured to me by the following 10 claims.

I claim: 1. A heavy duty arrester to ground violent surges of current flowing from a power line into a low voltage line and to create thereby a fault current for operating a circuit breaker in the power line comprising a plurality of electrodes in the low voltage line and a grounded electrode in spaced relation thereto to provide arcing gaps between said line electrodes and said grounded electrode, and fusible material carried by said electrodes, said electrodes having a sloping surface for feeding said fusible material into the path of arcing across said gaps to quickly lower the resistance and increase the fault current.

2. A heavy duty arrester to ground violent surges of current flowing from a power line into a low voltage line and to create thereby a fault current for operating a circuit breaker in the power line comprising a plurality of electrodes in the low voltage line and a grounded electrode, means for vertically positioning all said electrodes to provide arcing gaps therebetween, fusible material on the upper surface of said electrodes, said upper surface slanting in the direction of said arcing gaps whereby to feed said fusible material into the path of arcing across said gaps to quickly lower the resistance and increase the fault current.

3. A heavy duty arrester to ground violent surges of current flowing from a power line into a low voltage line and to create thereby a fault current for operating a circuit breaker in the power line comprising a plurality of electrodes in the low voltage line and a grounded electrode in spaced relation thereto to provide arcing gaps between said line electrodes and said grounded electrodes, and fusible material disposed in close proximity to said arcing gaps, said electrodes having a sloping surface for feeding said fusible material into the path of arcing across said gaps to quickly lower the resistance and increase the fault current.

References Cited in the file of this patent UNITED STATES PATENTS 658,976 Cook Oct. 21, 1900 768,196 Rolfe Aug. 23, 1904 1,049,366 Jackson Ian. 7, 1913 1,509,609 Pfiffner Sept. 23, 1924 2,271,573 Sands Feb. 3, 1942

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