US1513210A - Thermal relay - Google Patents

Description

Ocf. 28 1924. 1,513,210

H. F. BANAN THERMAL RELAY Filed June 9, 1920 2; 79 14" HA l 1 2a i a I Z 23 21 WITNESSES: Q INVENTOR I g )jvfdaafjfiazzmz BY 1 b ATTORNEY so tion.

Patented Oct. 28, 1924.

UNITED STATES PATENT .oFF ca.

HORACE F. BANAN, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A- CORPORATION OF PENNSYLVANIA.

THERMAL RELAY.

Application filed. June 9,

To all whom it may concern:

Be it known that I, HORACE F. BANAN, a citizen of the United States, and a resident of Pittsburgh, in the county of Allegheny 6 and State of Pennsylvania, have invented a new and useful Improvement in Thermal Relays, of which the following is a specification.

I My invention relates to thermal relays 1 and particularl to bimetallic relays.v

One object o my invention is to provide a relay havin a thermal-responsive device that inherent y shall have such heating characteristics as to ensure effective operation when connected in circuit with a device to be protected, without the use of aux: iliary heating devices.

Another object of my invention is to provide a bimetallic member that .inherently shall have high electrical resistance.

Another ObJGCt of my invention is to r0 v vide a relay of the cartridgetype that sliall have means whereby the thermal elements and contact members thereof may .be mount-.

ed as a unit on one ferrule of the cartridge;

A further object of my .invention is to provide a relay, of the above .indicated character, that shall be simple and inexpensive to construct and effectivein its opera- Heretofore, when thermal relays were used for the protection of electrical apparatus, it was found desirable, especially when the device to be protected consumed a relatively small value of current, to provide a heating element for the thermal-responsive member. This was found necessary by rea son of. the fact that insufficient heating was obtained when the thermal-responsive device was made of such mechanicalstructure' as to secure effective operation. In view of the above, I provide a bimetallic member of the required mechanical strength to obtain effective operation and 4 I slit the same alternately from opposite ends thereof to constitute an electrical conductor having relatively high-resistance. 'It will be seen that,v with this arrangement, sufiicient heat may be generated in a rela 0 tively large bimetallic'membenby a rela-,- tively small current traversing the same,to cause effective operation thereof, I further mount the bimetallic element and the contact'members, as a unit, on one ferrule of a 1920; Serial No. 387,579."

device of the cartrid e type, in order to ensure, at all times, e ective alinement between' the contact members and consequent accuracy of operation. Figure 1 of the accompanying drawings 1s a. View of the bimetallic element embodying my invention Fig. 2 is a view of the elefment'shown 1n',F g. 1 having bracing members at the ends thereof. Y

Fig. 3 is a view, partially in elevation and partially in section, of a thermal relay embodying my invention, and Fig. 4 is -a diagram illustrating the use of my; invention for the. protection of an electrical translating device a 0 A motor 1 or other electrical translating device to be' protected, isprovided with current from a circuit 2 through an. interrupter 3. The interrupter 3 is provided with a low-voltage holding coil 4 and a spring 5 for actuating the same when the coil 4 is de-energiz'ed. The circuit 'offthe coil 4 is controlled by a thermal relay '6 Ivhich is connected in circuit with-the motor I The thermal relay6,-as shown in Fig. 3,. comprises a cylindrical casing 7, two end ferrules Sand. 9 and a unitary thermal-re-.

in'g block 11- to which-is secured a bimetallic- .member 12 and an arm 13 upon the outer end. of which is. mounted a contact member 14, A contact member 15 is mounted on the I bimetallic member 12 but is insulated therefrom and is adapted to engage-the contactmember 14. The'block ll'lS securedto the ferrule 8 byrivets- 16.

.Th: bimetallic. member 12 comprises two strips ofm'eta-l'l? and'l8 having different 'temperature' coefficients and effectively sew cured togetherin face-to- facerelatiomj slits 19, 20 and 21 are cut inthe member 12 from theresp'ective'ends thereof in such'manneras to-greatlyxincrease the res stance to. the flow of current therethrough. That is, with the bimetallic member slit as shown. in. Figs,

,1 and 2, the resistance to the-flow of current from the point. 22- to the"p0i nt 23 is substantially sixteen 'times as great as the i resistance to the flow'of current from one end ,to the other ofthe original strip. The

point-22 of the strip is electrically connected b1}: ordinary cartridge-fuse clips. However,

spacing of the clips is such as to preclude the use of a device of this type in place of a fuse of the same rating.

Two insulating members and 26 are clamped to the outer end of the bimetallic element 12 for the purpose of so strengthening the same as to preclude uneven expansion of the various parts of the element and also for the purpose of insulating the contact member 15 from the strip 12. The contact member 14 is connected, through the supporting member 13 and a conductor 27, to a terminal post 28 which, inturn, is connected, through the coil 4, to conductor 29 of the circuit 2. It will be understood that the relay 6 is placed in series with conductor 30 of the circuit 2 in order that the coil 4 may be connected across the circuit.

Since the bimetallic element 12 is disposed in the casing 7 and, since the resistance to the flow of current through the element 12 is relatively high, it will-readily be seen that the device may be adjusted to cause disengagement of the contact members 14 and 15 when a predetermined value of current has traversed the motor 1 for a predetermined interval of time.

The heating characteristics of the device 6 may be such as to conform exactly to that of the motor 1 or they may be such that the time interval is sufiicient to secure adequate protection to the motor 1.

With my device, adequate protection will be obtained, irrespective of the current traversing the motor 1. That is, if the motor 1 consumes only a fraction of an ampere, sufficient'heating will obtain in the element 12 to cause the same to operate efiectively to deenergize the coil 4 which permits the s ring 5 to open the interrupter and thus dlsconnect the motor 1 from the circuit. The coil 4, being a low-voltage coil, will, of course, also permit the interrupter 3 to open when the voltage across the circuit 2 falls below a predetermined value.

Since the unit 10, comprising the bimetallic element 12 and the contact members 14 and 15, is mounted on one ferrule of the de- 'vice, it willbe understood that the necessity for accurate alinement of the ferrules 8 and 9 is obviated and thus a more accurate device is obtalned with less expense.

My invention is not limited to the specific structure illustrated as it may be-variously modified without departing from the spirit and scope of the same, as set forth in the appended claims.

,I claim as my invention:

1. An article of manufacture comprisin a bimetallic stri having slits therein extending alternate y from opposite ends.

2. An article of manufacture comprising a bimetallic strip having such slits therein,

extending. from the respective ends thereof, that the resistance of the strip is relatively arge.

3. An article of manufacture comprising two strips of material of different coeflicients of'expansion positively secured together in face-to-fa'ce relation and having slits there- 'in extending from opposite ends thereof.

so formed to cause them to move together when heated, and a contact member on said means.

7. A thermal relay comprising a bimetallic strip having slits extending such distances, alternately from the respective ends thereof, as to increase the electrical resistance of the strip and means for securing the separated portions of each end of the strip together. a

8. A thermal relay comprising a bimetallic strip having slits therein extending from opposite ends thereof and insulating means adjacent the ends thereof for securing the separated portions of the strip together to cause the torques of the several portions to be cumulatively effective.

9. A thermal relay comprising a bimetallic strip having slits therein extending from one end thereof, an insulating clamp for one end of the strip to cause the several portions to move together, means for supporting one end of the strip, and a contact member supported on and controlled by the free end of the strip. I

10. A thermal relay comprising a cylindrical casing, two end ferrules therefor, and a thermal-responsive device supported as a unit within the casing on one ferrule and electrically connected between both ferrules.

11. A thermal relay comprising a cylindrical casing, two end ferrules therefor, a bi- III Ill

metallic element supported on one ferrule only and means for electrically connecting the same to both ferrules.

12. A thermal relay comprising a cylindrical casing, two end ferrules therefor, a bimetallic element supported on one ferrule only and means for electrically connecting the element to the other ferrule.

13. A thermal relay comprising a cylindrical casing, two end ferrules therefor, a bimetallic element supported on one ferrule only and so slit from the opposite ends thereof as to constitute a conductor of relatively high resistance, means for connecting one end of the conductor thus constituted to the supporting ferrule and the other end to the other ferrule.

14. A thermal relay omprising a cylindrical casing, two end ferrules therefor, an insulating member, a bimetallic member secured to the insulating member, a stationary contact member mounted on the insulating member, a movable contact member mounted on the bimetallic member and means for mounting the insulating member on one ferrule only. 1

In testimony whereof, I have hereunto subscribed my name this 4th day of June, 1920.

HORACE F. BANAN.

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