US1750909A - Protective device - Google Patents

Description

March 18 W. J. STANTON PROTECTIVE DEVICE Filed April 9, 1928 Millard J 513% Patented Mar. 18, 1930 UNITED STATES PATENT OFFICE WILLARD J. STANTON, OI CHICAGO, ILLINOIS, ASSIGNOB, BE HESNE ASSIGNMENTS, TO AMERICAN ELECTRIC COMPANY, INC., OF CHICAGO, ILLINOIS, A CORPORATION OF DELAWARE PROTECTIVE DEVICE Application filed April 9,

This invention relates in general to protective devices, but more particularly to such devices used in telephone systems to rotect the operator of a telephone set from high po- 6 tential current induced in the telephone line.

It is the usual railway practice for each railroad of any size at all to have a telephone system of its own with the private telephone lines strung along the right-of-way for com- 10 munication between headquarters, stations,

andother convenient points. It is also commonfpractice for the railroads to install substations all along the right-of-way, these substations comprising a telephone set suitably mounted on the telephone poles carrying the line conductors.

Not only do these poles carry the telephone lines, but they generally carry cables through which flow currents of high potentia-l. Oft times it is necessary that the telephone wires be strung in close proximity to these cables, the result being a current of high potential induced upon the telephone line.

An induced current of this type is very dangerous to anyone having occasion to use one of these outlying telephones sets. To overcome this danger, it is the practice to install at each telephone set, protection in the form of an arrester permanently connected to the line. This method would be satisfactory if the arresters were not subject to trouble. But when the arresters are connected in the permanent manner, trouble results, and if the arrester is faulty, the operator of a telephone set is in' no way protected.

The permanent location of the telephone sets along the right-of-way entails considerable maintenance expense, since it is required that a man travel to these phones to repair and maintain them.

In order to overcome the objections related above, I propose to install in place of the telephone sets on the telephone poles, a jack box which has embodied in it special protective features. I also propose to equip each train with a portable telephone set so that if it is necessary that a member of the train crew communicate with some distant point, a talk 1928. Serial No. 268,470.

ing connection ma be completed through the exchange merely y connecting the set with the jack box, the connection consisting of inserting a plug with which the portable set is equi ped, into the jack in the pole box.

By urnishing portable telephone sets, the maintenance is greatly reduced, since all sets may be repaired at a central point.

The protective feature of my invention comprises connecting the telephone set to ground through carbon arresters before it is connected to the line, then connecting the set to the line through fuses, thus doubly protecting the operator of the set.

In this manner the protective requirements of the railroads are fully met and arrester troubles are obviated, since the arresters are connected to the lines only during the periods of converastion.

A more complete understanding of my invention may be had from the detailed description which is to follow, reference being had to the accompanying drawings in which:

Fig. 1 is a front View of the jack box with the front portion of the cover removed to ihow the jack and protector equipment in the Fig. 2 shows, diagrammatically, the circuit connections of the various parts shown in Fig. l.

The construction of my invention as shown in Fig. 1 will first be explained in detail. The box which is mounted on the telephone pole is made of cast iron or any other suitable weather-resisting material, and it comprises the base 1 and cover 2. The mounting flange 3 is cast integral with the base 1 in a direction perpendicular to the base. Flange 3 is provided with holes 4: through which may be inserted lag screws for the purpose of mounting the vase on a pole. When mounted on the pole, the surface of the base will be in a horizontal plane. The cover 2 is adapted to fit over the base 1 with its edges overhanging the base as shown in the drawing. In this manner, rain, snow, dirt, or any other substance is kept from entering the box. The cover may be fastened to the base in any desirable manner.

The jack assembly is composed of two individualjacks 7 and 8. Each individual jack has two contact springs, 9 and 10. It will be noticed that the spring 9 of each jack is longer than its associated spring 10. The reason for providing springs of different lengths will be explained shortly hereinafter. The j acks'7 and 8 are rigidly mounted in the insulating piece 11 which is firmly secured to the plate 1 by means of screws. An opening is provided in plate 1 to clear the ends of the jacks 7 and 8.

The posts 5 and 6 are also cast as a part of the base 1 and are provided for the mounting of the protector equipment.

The protector equipment may be any wellknown arrester, but preferably that shown and described on page 5 of the catalog of the American Electric Co. Inc, Chicago, Illinois, which catalog is entitled Telephone Construction Material and Supplies. This arrester consists of two pieces of porcelain, 12 and 13, one carrying fuse clips for the line end, the other carrying fuse clips for the instrument end. In the porcelain 12 carrying clips for the line end, carbon arresters 21, separated with dielectrics about .007 of an inch thick, are placed in a well and covered by an insulating metal cap 14. The porcelain 12 is mounted on post 5 by means of screws 15, while porcelain 13 is mounted on post 6 by means of screws 16. Two fuse clips 17 are mounted on porcelain 12 and two fuse clips 18 are mounted on porcelain 13. These fuse clips are so arranged to receive the fuses 19 and 20 as shown in the drawing.

Referring now to Fig. 2, a description of the operation will be given.

At A is shown a portable telephone set having the usual talking, receiving, and signalling instrumentalities. The telephone set is equipped with a plug P having two plug terminals. The springs 10 of jacks 7' and 8 are connected to the telephone line through the fuses 19 and 20. Springs 9 are connected to the carbon arresters 21 which are connected to ground.

When a call is to be made, the plug is inserted in the jack assembly. As the two terminals of the plug are inserted into the jacks 7 and 8, the first contact is made with springs 9 which are longer than springs 10 and which are connected to the carbon ground. Thus the telephone set is first connected to ground, protecting the operator from any high potential current which might be on the line outside of the jack assembly. The second contact made by the terminals of the plug P is with springs 10. This contact connects the telephone set to the line through the fuses 19 and 20. By connecting the set to the line through the fuses, additional protection is furnished.

Although I have chosen the foregoing manner in illustrating my invention, it is not my intention that my invention shall be limited to the exact disclosure, for there are modifications and adaptations which could be made by those skilled in the art.

Having thus described my invention, what I consider new and desire to have protected by Letters Patent, is pointed out inthe appended claims.

What is claimed is:

1. In a telephone system, a jack having tip and ring contacts, lightning arresters connected to said tip contacts, line conductors connected to said ring contacts, and a plug to which is connected talking instrumentalities, said plug upon insertion in said jack first making contact with said tip contacts to connect said instrumentalities to said arresters before connecting the same to said line conductors.

2. In a telephone system, a jack assembly comprising two individual jacks, a tip contact and a ring contact in each individual jack, a plug having two contacts, one for each individual jack, talking instrumentalities connected to said plug, a lightning arrester connected to each tip contact, and a line conductor connected to each ring contact, said plug contacts making contact first with said tip contacts to connect said instrumentalities to said arresters and thereafter making contact with said ring contacts to connect said instrumentalities to said line conductors.

3. In a device for protecting the operator of a portable telephone set, a plug connected to said set, a jack, a line, lightning arresters, means in said jack for first connectingthe telephone set to said arresters upon the insertion of said plug in said jack, and means Ill)

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