US1023264A - Switch. - Google Patents

Description

J. F. MGELROY.

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APPLICATION FILED AUG. 8, 1903. 1,023,264. PatentedApr. 16, 1912.

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J. P. MGELROY.

SWITCH.

APPLICATION 211.511 was, 1903.

1,023,264. Patented Apr. 16, 1912.

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UNITED STATES PA ENT OFFICE.

JAMES F. MOELBOY, OF ALBANY, NEW YORK, ABsIGIl'OB TO CONSOLIDATED GAB HEATING COMPANY, A. COBPOBATIQN OF WEST VIRGINIA.

SWITCH.

Specification of Letters Patent.

Patented Apr. 16, 1912.

Application filed August 8, 1908. Serial No. 447,510.

To all whom it may concern:

Be it known thatI, JAMES F. MOELBOY, a citizen of the United States, and a resident of the city of Albany, State of New York, have invented certain new and useful Improvements in Switches, of which the following is a full, clear, and com lete disclosure.

This invention relates to t c class of overload or cut-out switches for electric circuits, and the object thereof is to produce'a switch which will break the circuit when any abnormal condition exists in the circuit, such as a ground or short circuit, but which will not be operated by other sudden increases in the amount of current flowing, such as when the devices operated by the current in such circuit are being started up, unless so described.

My improved switch is particularly adapted for circuits in which heating elements are included, such as heatin elements for supplying heat to steam boi ers for the generation of steam for heating purposes and as one illustration I have shown this application of the invention.

Boilers such as those just referred to are particularly adapted to the heating of railroad trains drawn by electric locomotives, and where the boiler is located on the locomotive so that the steam heating devices already installed in railroad cars previousl drawn by steam locomotives may be use This system of heating by steam generated through the action of electric current flowing through electric heaters forms no part of my present invention and is merely shown to illustrate one use .for that invention.

As will be seen from Fig. 1 of the drawing, the heaters shown consist of metallic tubes adapted to carry an electric current, and located within the boiler tubes or flues but not contacting electrically therewith. The surfaces of these parts are ordinarily separated only by about five-eighths of an inch of air space, and under abnormal or accidental conditions, the current might pass from the heating tube to the metal of the boiler, thereby causing a short circuit or ground, it being understood that the metal of the boiler is grounded because it is carried on the metallic frame of a car or locomotive.

In overload switches of the style previously used with motors on electric cars and mately two and one-half with such apparatus as an electrically heated holler, the switch is intended to prevent an overload of current in case any accident happens to the apparatus, such, for example, as aground or short-circuit. It is always desirable to open a circuit through any translating device in case a ound occurs, and such overload switches ave generally been arranged so that the controlling magnet will carry the maximum current without releasing theswitch when the current is acting normally, but when the ground occurs the extra current thereby produced is supposed to operate the magnet and open the circuit. However, when a device like an electric motor is used, whose starting current is large compared with the ordinary normally running current, the overload switch heretofore employed must be adjusted so that the maximum current necessary for starting or running the motor will be carried without operating the switch, and on the other hand so that an excessive increase of the current, due to grounding, shall operate the switch to open it. When electric'heaters having a large heat coefiicient are employed in the circuit, there is always a heavy rush of the current through the heater until the same becomes heated up and its resistance thereby increased. An overload switch of the prior kind must therefore be adjusted so as to carry approxitimes the normal current, and so that the rush of the current through the heating element when it is first started will not open the circuit. The overload switch which forms the subject of my present application, is, on the contrary, so devised as not to open with any current however large that may be sent through the heaters, but to open only when a ground or short-circuit takes place in some part of the apparatus and by reason of the fact that the ground or short-circuit establishes a condition difi'erent from that which would be established by a mere increase in the total current.

For a full, clear and exact description of that one form of my invention which I at present deem preferable, reference may be had to the accompanying drawings forming a part of this application, in which- Figure 1 shows the boiler with the heating elements therein, and shown partly in section, said boiler being electrically connected to my improved overload switch shown in perspective; Figs. 2 and are diagrammatic views showing my improved switch connected respectively with a heating device or boiler and with an electric motor; Fig. 4 shows a slight modification and Fig.5 a diagram thereof.

Referring to the drawings, the numeral 1, Fig. 1, indicates the casing of a boiler; 2 the boiler tubes; 3 the heating elements therein; 4 the insulators at the end of the tubes "for locating and holding the heaters in position; 5 the connectors for connecting the heating elements 3 in series; and 6 and 7 indicate the leads connecting the heating elements with the overload switch. The overload switch comprises (see Figs. 1 and 4) a base 8 upon which are mounted the usual stationary contactor strips 9 of the usual or suitable material, such as carbon, and the movable contact strips 10 carried on a yoke 11. The yoke 11 is also provided with the usual metallic connecting blades 12 which enter the flexible contact jaws 13, also carried by the base and electrically connected with the strips 9. The yoke 11 is carried on an arm 40 pivoted at 42 and contacts with the spring 14 for forcing the arm 40 outward when the switch is released. An elastic bufl er 144 is provided for lessening the upward blow of the arm as the switch opens and retaining it in its open position. A projection 15 on the yoke 11 is adapted to engage a pivoted latch or pawl 16, which carries the armature 17. Opposite the armature 17 is placed the core 18 upon which are several turns of wire forming two coils as indicated in 19 and 20, wound in opposite directions, and included respectively in the leads 6 and 7 from and to the elements 3. Upon the latch 16 there may be mounted a small weight 21 for varying the sensitiveness of the overload switch. This weight may be entirely omitted in case it is desirable that the switch shall be very sensitive.

The numeral 22 indicates the third rail or other stationary conductor for supplying current to the apparatus, and 23 indicates the contact shoe cooperating therewith. The lead 24 terminates at the connector 25 which is electrically connected with one set of the stationary contact strips 9 and 13. Connector 26 is electrically connected with the opposite set of contact strips 9 and 13, and when the yoke 11 is in operative position between the two sets of contact strips 9 and 13, the circuit is closed. The connector 26 is connected with the lead 27 forming one end of the coil 20 and the other end of the coil 20 is connected with the lead 7 supplying current to the heating elements 3. The lead 6 is connected to one end of the coil 19, and the other end of said coil 19 is connected with the lead 28 passing to the return conductor, conventionally indicated as the ground 29, connector 30 being interposed for this purpose.

When the switch is closed the current from the third rail enters through the shoe 23, lead 24, one set of stationary contact elements 9 and 13, one set of movable contact elements 10 and 12, the yoke 11, the opposite set of movable contact elements 10 and 12, the other set of stationary contact elements-9 and 13, the connector 26, coil 20, the lead 7 the heating elements 3, the lead 6, the coil 19, the lead 28 to the return 29. Since the current passes through the coils 19 and 20 in opposite directions, they tend to neutralize each other when the normal or even the heavy starting current, however great it may be, is passing through the heaters, but should a ground take place from any of the parts beyond the coil 20 as indicated, for example, at 54 in Fig. 5 the current in one of the coils will be increased since that coil will be in series with the ground and the magnetism which was before balanced, will be lessened or eliminated in the other coil which has been shunted by the ground and the latch operated to open the switch. This arrangement enables the switch to be opened when a ground occurs even if the ground should not cause any increase of the total current from the third rail or stationary conductor through the apparatus. It will thus be seen that I have provided a switch which does not require an abnormally large current to operate it, but operates through a division of the current supplied to the heating elements or motor, such as in the case of a ound, the current being diverted directly oin the grounding point to the ground or return conductor without passing through one of the coils of the switch.

In Fig. 3 the numeral 31 indicates an electrio motor which is controlled in the same manner as the heating elements in the boiler 1, shown in Figs. 1 and 2. In Figs. 2 and 3 the movable element of the switch is indicated by the numeral 32, and the stationary elements by the numerals 34 and 35, the spring for operating the switch being indicated by the numeral 36. The other parts in these figures corresponding to Fig. 1 are indicated by the same reference numerals as in Fig. 1.

As shown in Figs. 4 and 5, the neutralizer coil 19 which is shunted by the ground, may oppose coil 20 mechanically, as well as magnetically. Thus in Fig. 4 the latch 16 is mounted on a rod 50 and normally held by spring 52 in engagement with projection 15 on yoke 11, the longitudinal play of rod 50 being limited by collars 53, 53. The pull of coil 20 on rod 50, against the tension of spring 52 is neutralized by the contrary pull of coil 19; When, however, coil 19 is shunted by a ground in the protected apparatus, it lets go of the rod which then responds to the pull of coil 20, which is in series with the ground, and the switch is released. The collar 53 serves to limit the motion of the core when the conditions are normal. The end portions 50' of said core are made of non-magnetic material.

While the arrangement above described is one that illustrates the principle of a cut out switch provided with a neutralizing coil that normally opposes (either magnetically or mechanically) the operating coil of the switch, but lets go in the event of a ground or short-circuit in the apparatus, yet the same principle may be also applied to a switch that will respond, like an ordinary cut-out to an excess of current in the apparatus, while still retaining the quality and characteristic above described. Thus if the coil 20 has one or more extra turns, as shown in Fig. 3, it will have an excess of power over coil 19 proportional to the product of the number of extra turns by the amperes of current. If, for example, there is one extra turn and the normal or satisfactory current which is below the responding point of the cut-out is two hundred amperes, then the excess power will be two hundred ampere turns and the adjustment may be such that an excess of this amount will not cause the cutout to act. If, however, the current exceeds this value, the switch will respond and open the current. At the same time an accidental ground in the apparatus will short-circuit coil 19 and coil 20 will then act by removal of the opposition of coil 19, instead of by excess current in its supernumerary turn or turns.

Havin thus described my invention, I do not wish to be understood as being limited to the exact details of construction or arrangement of parts set forth, for various changes may be made in my invention by persons skilled in the art without departing from the spirit and scope thereof.

What I claim and desire to secure by Letters Patent is:

1. A switch comprising a core having coils traversed by the current, the coils exerting a force normally in opposition, said coils be ing responsive to an excess of current and also responsive to the shunting of the current through one of the coils to the ground.

2. In a cut-out switch, means for opening said switch comprising current-carrying devices of unequal force and responsive to an excess of current, and also responsive to the shunting of the current through one of said devices by a ound.

3. In combination with a translating device, a cut out switch having coils traversed by the current passing through said device, one of said coils exerting a force counterbalancing a fraction of the force of the other coil and said coils being responsive to an excess of current, and also responsive to the shunting of the current through one of the coils by ground.

4. In combination with a translating device, a cut out switch having unequal differential coils traversed by the current passing through 'said device, said coils being responsive to an excess of current, and also responsive to the shuntin of the current through one of said devices%iy a ground.

5. In a cut-out switch, differential controlling coils in series and normally inactive upon said switch,one coil having a greater number of turns than the other, and a translating device located in the circuit between said coils.

Signed at Albany, county of Albany, State of New York, on the 6th day of Aug, 1908.

JAMES F. MCELROY.

Witnesses:

BEULAH CABLE, JOHN M. ESTERLY.

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