US2644115A

US2644115A - High-voltage arrester

Info

Publication number: US2644115A
Application number: US208011A
Authority: US
Inventors: Roy G Sands
Original assignee: Automatic Electric Laboratories Inc
Current assignee: Automatic Electric Laboratories Inc
Priority date: 1951-01-26
Filing date: 1951-01-26
Publication date: 1953-06-30
Anticipated expiration: 1970-06-30

Description

June 30, 1953 I SANDS 2,644,115

HIGH-VOLTAGE ARRESTER Filed Jan. 26, 1951 ""4 I N V EN TOR.

ROY s. smos ATTORNE Y Patented June 30, 1953 HIGH-VOLTAGE ARRESTER Roy G. Sands, Waukegan, Ill., assignor to Automatic Electric Laboratories, Inc., Chicago, 111., a corporation of Delaware Application January 26, 1951, Serial No. 208,011

4 Claims.

The present invention relates in general to protective devices for electrical circuits and more particularly to arrester's which are capable of protecting communication circuits from destructive damage when crossed with extremely high voltage lines.

Communication circuits are, at the present, normally protected at both the central office and substations from abnormal currents, such as would be found when the circuit is struck by lightning or is crossed with a high power transmission line. These protectors have taken many forms and generally consist of an automatic high voltage discharge block, or a fuse, or a combination thereof. Such arrangements have been generally accepted throughout the communication industry and are recognized as being both valuable and necessary in order to protect both property and life from the hazards of high potential currents.

The recent expansion of the Rural Electrification Administration has presented the communication field with a new and alarming hazard. The high voltages and currents carried by the REA lines far surpass those carried by high power lines in the past. The basic fear created by these lines is due to the fact that the voltages and currents carried by them greatly exceed the conditions under which the present day protective devices were designed to operate satisfactorily. In fact, the power carried by these lines is sufficient to break down the insulation pro vided by the standard protective devices and is capable of exposing the communication equipment to the dangers of a high potential in spite of their use.

It is therefore an object of this invention to provide a novel protective device which is capable of protecting circuits from injury due to the extremely high voltages. A further object of the invention is to provide an overvoltage protecting device which is rapid in operation, is capable of automatically freeing the circuit after the hazard has been removed and iscapable of operating many times before it requires human attention. A further object of the invention is to provide an efiicient and reliable device for protecting several of such circuits from injury due to high voltages which is economical to manufacture.

Other objects will be clear from the following specification taken in connection with the annexed drawings in which:

Figure 1 is a front view in which the cover has been broken away to show the components of the structure;

Figure 2 is a sectional view taken along line 2--2 of Figure 1;

Figure 3 is a perspective View of the bi-metallic element, which will be more specifically described hereinafter;

Figure 4 is a sectional view taken along line 4-4 of Figure l. i

As shown in Figures 1 and 4, the protector includes a base it which supports an insulating block H, made of a suitable electrical insulating material, such as glazed porcelain. The base [0 and the block H are supported by a bracket l2 and are fastened thereto by any well known means, such as machine screws 13. The bracket i2 may be constructed in any manner suitable to the location and position in which the protector is to be mounted. The entire structure may be covered and protected by a cover M which can be loci-red. place or secured to the base Ill by any of the well known locking means, such as screw i5.

The block of insulating material II has a series of raised embossings 20 and 2|. They include one centrally located embossing 20 and four outer embossings 2!, which are disposed about the central embossing 2D. This arrangement is only one of those which could be used within the spirit of the invention, the particular number of outer embossings not necessarily being fixed at four. A heavy carbon electrode 22 is mounted on the central embossing 20 and a similar heavy carbon electrode 23 is mounted on each of the outer embossings 2 l. The outer electrodes 23 are each secured in place by a fastener 24 which engages a conductor terminal clip 25. Each of these clips 25 is electrically connected to a heavy current conductor 26, by which the electrode may be connected to any desired line conductor or other portion of a communication circuit, not shown. The space between the adjacent sides of the central electrode 22 and each of the outer electrodes 23 is carefully adjusted, as will hereinafter be shown necessary. These spaces are all approximately equal and are somewhat smaller than the spaces between adjoining outer electrodes 23.

The center electrode 22 is held in position by shaft 21, the bottom end of which engages a conductor terminal clip 28 and the upper end of which is engaged by a washer 29 and lock-nut 30. The conductor terminal clip is electrically connected to a heavy current conductor 28a, the other end of which (not shown) is connected to ground. A tubular spacing bushing 3| may be mounted on the upper end of the shaft 21 in order to support a bi-metallic element 32. The

bi-metallic element 32, as shown in figure 3, has four projections 33 extending outward from the hole which engages shaft 21. Each of these pro jections is arranged to lie directly above one of the outer electrodes 23. The bi-metallic ele ment 32 may be fastened to the shaft 21 by any suitable means, such as the lock-nut 34 and washer 35.

A heavy carbon contact block 36 is attached to the end of each of the bi-metallic element projections 33 and is fixed thereto by fasteners 31. The lower face 38 of each of the contact blocks 36 is diagonally biased so that the contact block 36 will abut its adjacent outer electrode 23 in surface contact when the bi-metallic element projection 33 is flexed downward, as will be hereinafter explained. The space between the contact block 36 and its adjacent electrode 23, at the nearest point, is adjusted so that it is equal to the space between the outer electrode 23 and the central electrode 22.

Now that the structural features of my new protector have been set out in detail, I will explain its operation when an extremely high voltage current is attached to the circuit to which one of the conductors 26 is connected. This con nection will carry the potential to the outer electrode 23 which is associated with the circuit so effected. If this foreign potential approaches the voltage and current limits of the standard communication circuit protectors, it will be sufiicient to break down the air gap between the outer electrode 23 and the central electrode 22 to form a primary spark gap between said electrodes. Since the contact 36 is also connected to ground through element 32 and shaft 21, a secondary spark gap will be formed between the contact 33 and the outer electrode 23. The heat formed by these two spark gaps is very intense and immediately causes the bi-metallic element projection 33, which is associated with the spark gap contact 36, to flex downward and bring the contact 38 and outer electrode 23 into contact. Since the contact 33 has its lower face 38 biased, the contact 36 and electrode 23 are brought into surface to surface contact, which will short circuit and completely disable the spark gaps. The bi-metallic element 32 will remain flexed and maintain its projection 33 in a downward position as long as the high voltage current is fiOWlllg therethrough.

After the source of high voltage current has been disconnected from the communication circuit and its resulting potential removed from electrode 23, the bi-metallic element 32 will be free from the effects of both the spark gap heat and the conduction of high voltage current and will, as a result, restore its projection 33 to its normal inoperative position as shown in Figure 1. The protector is now in condition for reoperation should the source of high potential again be connected to the associated communication circuit.

Thus it can now be seen that each outer electrode 23, its adjoining carbon contact 36 and associated bi-metallic element projection 33 form a separate arrester unit in conjunction with the common central electrode 22. Normally, each of these units is available for protecting a different circuit, the particular arrangement disclosed herein being capable of protecting four such circuits. The number of circuits to be protected and, correspondingly, the number and arrangement of outer electrodes 23 could be varied in accordance with the conditions in which the protector is to be used without avoiding the scope of the invention. If, in the future, any communication circuit is exposed to the hazard of a high power line which exceeds the rated capacity of one of these arrester units, two or more of the units may be connected to the circuit in parallel by merely connecting two or more of the outer electrodes 23 to the circuit instead of one. This will then reduce the power discharged by each unit to a value well within its capacity.

A protector made in accordance with my invention will successfully and satisfactorily arrest high voltage currents of the order of 12 kilovolts and will successfully and satisfactorily reoperate after the arrester has automatically reset itself. These currents are arrested in an extremely short period of time after they are imposed upon the line, the time lapse in some cases being of the order of 5 milliseconds. From this, it may readily be seen that this protector will not only ground the foreign high potential, but will operate rapidly enough to prevent any destruction to equipment or persons during the time such potentials are imposed upon the line. This protector is not intended to replace the protective equipment now in use in communication equipment but is intended to supplement such devices and arrest foreign currents which exceed the capacity of the standard devices.

Having described my invention in detail what I desire to protect by Letters Patent in the United States is:

1. In a high voltage current protector, three carbon elements, the first and second. of said elements immovably mounted adjacent one another, the side surfaces of the first and second of said elements forming a first spark gap, a bi-metallic strip, one end of said bi-metallic strip mounted on said first element, the other end of said lei-metallic strip supporting said third element so that the surfaces of said. second and third elements form a second spark gap, said first element, said bimetallic strip, and said third element forming a current path, said second element passing high voltage current to said first and third elements through said spark gaps, said bi metallic strip flexed responsive to the heat of said spark gaps to bring said third element into contact with said second element to form a high current discharge path from said second element directly to the third of said elements and through said bimetallic strip and said first element.

2. In a high. voltage current protector, a centrally disposed first electrode immovably mounted in said protector, a plurality of second electrodes immovably mounted in said protector and disposed about said first electrode in spaced apart relation and each of said second electrodes having a surface in close proximity with a side of said first electrode to form a plurality of first spark gaps, a bi-metallic element mounted on said first electrode and means including said element for forming a plurality of second spark gaps with each of said second electrodes, said element and means forming a current path from each of said second spark gaps to said first electrode, said element flexed responsive to the heat of a high Voltage spark at any of said plurality of second spark gaps to close that spark gap to form a high current discharge path from said second electrode directly to said means and to said first electrode.

3. In a high voltage current protector, a centrally disposed first electrode, a plurality of sec-- ond electrodes disposed about said first electrode in spaced apart relation and each of said second electrodes having a surface in close proximity with a side of said first electrode to form a plurality of first high voltage discharge gaps from said plurality of second electrodes to said first electrode, a bi-metallic element mounted on said first electrode and having a plurality of projections, a plurality of third electrodes, one of said third electrodes mounted on each of said projections, each third electrode in close proximity with respective ones of said second electrodes to form a plurality of second high voltage discharge gaps, each projection of said bi-metallic element flexing responsive to the heat generated by its corresponding second high voltage gap to move said corresponding third electrode into contact with said associated second electrode whereby said last mentioned high voltage discharge gap is closed.

4. In a protector as claimed in claim 3, each of said third electrodes having a surface, which in close proximity to said associated second electrode, angularly disposed so that the flexing of each of said projections brings the planes of the angularly disposed surfaces of said electrodes in to parallel contact with the respective planes of said second electrodes.

ROY G. SANDS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 768,196 Rolfe Aug. 23, 1904 2,124,364 Brach July 19, 1938 2,141,490 Sands Dec. 2'7, 1938