US947981A - Electrical time-limit switch. - Google Patents

Description

P. K. STERN.

ELECTRICAL TIME LIMIT SWITCH.

APPLIOATION FILED MAR. 18, 1902.

947,981 Patented Feb. 1, 1910.

2 SHEET88HEET 1.

Winesses;

P. K. STERN.

ELBGTRIGAL TIME LIMIT SWITCH.

APPLICATION FILED MAR. 18, 1902.

947,981. Patented Feb. 1, 1910. 2 SHEBTSSHEET 2.

I P U m E92 m w l T 2 11L E" M 9 4 IFD J4 W :'I .5 mmww" a I I h M bwe/zhr W/ j If UNITED STATES, PATENT OFFICE.

PHILIP STERN, OF NEW YORK, N. Y., ASSIGNOR TO GENERAL ELEGTBIC COMPANY, A CORPORATIQN OF NEW YORK.

ELECTRICAL TIME-LIMIT SWITCH.

Specification of Letters Patent.

Application filed March 18, 1902.

Patented Feb. 1, 1910.

Serial No. 98,762.

To all whom 'it may concern:

Be it known that I citizen of the United cit of New York, in the county and State of New York, have invented certain new and useful Improvements in Electrical Time- Limit Switches, of which the following is a specification.

My invention in time-limit electrical switches relates to that class of electrical switches having an electromagnetic motor, usually in the form of a solenoid disposed between the bridges of the switch for releasing a catch hook, upon the overload of electrical current carried by the circuit wires and conductors in which the switch is included, whereby suitable projecting springs ars disposed in connection with the bridges of the switch, to throw the same into an open position when the catch has'heen struck by a plunger or armature of the electromagnetic motor or solenoid aforesaid. In thls connection my improvements have relation to a means whereby an overload may be maintained for a desired period of time betore the circuit of which the switch forms part, is interrupted.

I am aware that, previous to my invention in automatic time-limit switches, means have been employed in connection with switches of this character for limiting the time of the overload by means of clockwork and analogous devices.

It is the object of my invention to provide a means carried b the switch base, which is more sim le an efiective in its operation and less lia 1e to err than those of which I.

am at present aware, or previous to my invention, and particularly less so than that class employing clockwork to accomplish the same ob ect.

Another object of my invention is to devise a means of the character stated, for lim- Pn'imr K. STERN, a j tates, l'tSldlilg in the i show ing iting the time of the overload for electrical i circuits, which may be readily applied to switches of the character known as bridging contact electrical switches.

In carrying out my invention I have illustrated the disposition of my time-limiting devices for two difierent types of switches in the two sheets of drawings hereto annexed, which form part of this specification, and in whichtil Fi re 1 is a front elevation of an electrlca switch of the bridging contact patter-u.

two solenoid electromagnets with which accomplish the purpose of my invention, illustrated in section, the section being taken through the two solenoid magnets and cores verticall Fig. 2 illustrates a similar. disposition 0 the time-limit features, showing the manner in which the two solenoids co-act when one. is placed vertically over the other. In this figure I have shown a side elevation of an electrical bridging contact switch of a somewhat narrower and longer pattern than that illustrated in Fig. 1. In the two figures I have shown the manner by which I carry out the details of the same principle employed in the one case on a wide and rather short switch, and in the other. a somewhat elongated and narrow ty e; and Fig. 3 'is a detailed viewof an in ex for adjusting the time-li1nit, and another index for the strength of the current during the interval of time for which the aforesaid index has been set.

In the drawings, similar characters of reference indicate similar parts.

In applying the time-limit principle aforesaid to switches of this character I have considered the adaptation of a retard ing medium, such as that of a viscous fluid contained in a closely fitting chamber in which the solenoid plunger is adapted to move in a manner whcreb the fluid will be required to be displace by the plunger through calibrated apertures permitting only of a predetermined quantity of transfor of the viscous fluid from the cylinder or chamber in which it is confined, to an escaping cylinder in which it is withheld and caught as the plunger is drawn into the solenoid by the magnetic action of the field of force generated by the current as it circulates around the convolutions of the solenoid; and to this end I have preferred the use of such viscous fluid as glycerin, well boiled, so as to eliminate air and moisture from the same, whereby the adhesion of the fluid to the walls of the cvlindcr or chamber in which it is confined during its resisting force against. the solenoid. may be as nearly uniform and constant as possible; and in employing prepared glycerin for the purpose of maintaining the. greatest constancy of the solenoid in the manner aforesaid, l have con tructed the confining chamber or cylinder. together with the retaining cylinan, in a manner whereby the same will any possibility of moisture be practically moisture-proof so as to avoid ing'absorbed by the glycerm while the switch is in long continued use in dam or steamy atmospheres such as would e encountered when applied to switch-boards or panel boards in dynamo or engine rooms. It is well known that glycerin in its almost chemically pure condition isextremely hygroscopic, and when considerable moisture ias been absorbed by the gl cerin the value of it as a" retarding agent ecomes unknown and, unless such precaution is resorted to against the accumulation of moisture, the time-limit features of the switch could not be depended upon.

In carrying my invention into practice I have preferred to describe the same in con nection with that type of switch in which the projecting mechanism for throwing the switch bridges into an open position, 1s 111.

the form of a spring energized plu er A,

and since I do not propose to claim t is as any part of my invention, an extended description of the same is not deemed necessary, as any means whereby the switch may be thrown into an open position will be readily understood by those who are skilled in the art to which my invention appertains. The manner in which the pro'ectmg device is released b the usual solenoid and plunger 0 C, 'is l' ewise of that'character which is familiar to those who have made a study of automatic electrical circuit breakers, and is therefore sufliciently clear in the illustration to require no particular description. My invention therefore will be confined to that part of the circuit-breaking system con- 1 tained within the solenoid B and its combination with the solenoid C and its concomitants. Extending within the solenoid B, is a tubular casing D between the head E of the inner tubular.fluid-containing chamber D and theupper guide M, connected to the solenoid, the upper end of said chamber D, bein in ement with an inner threaded portion E 0 such guide, for the purpose of rigidly hol sai tube to its bearing in the head e extremity of the cas' relation with the. gui e M, by means of gaskets and confining rings ably clamped by set screws G G. In the upper portion of the fluid-containing chamber D are a series of small outlets f, ti, whereb the glycerin F contained in e fluid c amber is allowed to escape, as will be hereinafter more fullyexplained. At the opposite extremity of the fluid chamber D are similar openings f, f arranged in valve-tight connection with corresponding openings h, h formed in the lower upturned inner ortion i and iof the outer casing D. e arrangement of the aforesaid openings h, h and f, f is D is in fluid tlg l ili.

such as to form a sort of stop cock at the lower extremity of the-confining chamber D and outer casing D whereby upon rotating the outer casin D by the milled head H, communication etween the outer casin D and confining chamber D may be cut 0 or established after the manner of a valvetight vstop cock. This 'feature of my invention afi'ords one means of limiting the time in which the glycerin is allowed to circulate between t e upper openings 1 and j, the lower 0 enings aforesaid, and the intzrior of the con ning chamber at its lower en Within the confining chamber D' is a core of inductive material 1,. closely fitting the w'alls of the confining chamber in a manner so that no glycerin will be permitted to pass between the line of division of the perimeter of the cylindrical surface of the core I, and the internal cylindrical surface of the confinin chamber D. To carry the core I so that its pole I may be introduced to different distances in the solenoid B, I provide an adjustable rest in the form of a column or spindle J, which passes throu h a stuffing box which is rovided wit the usual glan packing. ormed in the column or spindle J is a spline In; and a key K, slidmggy enlgag'ed in the spline issecured to the fix co ar-K of the casing, which latter is secured by rivets, screws or other mechanical means, to the lower extremity of the fluidcontaining chamber D. Upon shifting the column or spindle J b the milled head or thumb piece L, whic is retained by screw 1 and engaging shoulders Z and Z", a vertical movement may be imparted to the column-or spindle so as to adjust the ole I of the core in the zone of magnetic in uence of the solenoid B. Thus it will be readily understood how I am enabled to vary the magnetic induction between the solenoid B and the pole I of the core I, as well as the circulation of the glycerin F in the confining chamber D, outer casin 'D, and communicatin openin f, f, and h.

Sli ingly p aying in the integral guide M is a ta pet m, adapted to im inge against a pivote lever N, as the core Pis drawn into the solenoid B b -d namic induction sufli- 'ciently'to strike t e ower extremity of the tappet m, so as to raise the same and effect the movement of the lever N. The purpose of the leverN is to raise the sliding tube 0' and' plunger 0' of the solenoid C so as to bring the pole I sufiiciently within the the p magnetic induction of the solenoid C to en-' I with its concomitants, while illustrated in the usual manner for tripping the springactuated mechanism of the circuit-breaker, is disposed in a manner whereby my time limit solenoid magnet B and its concomitants are conjointly operating to produce rupture of the circuit of which the switch forms part. when the overload has become of such a character that will induce a sutli cient number of lines of magnetic force to raise the core of the solenoid'B' against the retarding effect of the glycerin F. in that time for which the retarding effect has been predetermined by the position of an index Q, denoting the number of seconds or minutes allotted for operation.

It will be understood by a careful study of the conditions that the two solenoidal systems co-act with each other upon a time limit for an overload, while on instantaneou overloads they operate independently. The function of this will be clear when a study of the solenoid C is resorted to independently of the solenoid B. As an explanatory example, a so-called ,short circuit may be considered as an excess of overload over that which the circuit is designed to carry, and under which conditions the switch would simply act as a circuit-breaker operating under the control of the solenoid C. The plunger 0' being previously set to its lowest extrei'nity. or to a position which would be comnu-nsurate with the operation of the same by a current circulating around the solenoid t". for a given short circuit expressed in the value of current strength in amperes, will project the plunger 0' violently into the magnetic field of the solenoid to a sufficient extent to bring the pole piece 1" into contact with the releasing catch as aforesaid, in a. manner to release the switch and break the circuit: but in the meantime, due to the retarding effect of the glycerin upon the plunger 1. the solenoidal system B will not have had a sufficient time within which to effect a rupture of the circuit by the performance of its function upon the lever N, and in this sense the switch would operate merely as a. circuit-breaker. On the other hand however. should the over load be insufficient to raise the plunger 0' into the magnetic field of force of the solenoid .-the plunger I being adjusted to operate. on a current: strength having a smaller valuewill be drawn into the magnetic field of the solenoid P). but being retarded by the resisting force due to the contined glycerin F, the circuit-breaking plunger (Y will not be sufficiently introduced into its magnetic field aforesaid until the pole l of the plunger 1 shall have contacted with the tappet m, in a manner so asto raise the lever N and tube 0 which carries the plunger O as aforesaid. and in this sense the two solenoidal systems B and G are interdeendent. It, will thus be understood by my invention that I am enabled to provide a means whereby a circuit-breaker having a constantly acting retarding means may be adjusted so as to maintain an overload on the circuit which it designed to protect for a predetermined period, and at the same time instantly rupture the same circuit upon an excessive overload.

A feature of my invention which 1 consider important in connection with circuitbreakers, which is a characteristic of the particular manner in which I carry out the principles aforesaid. lies in the re-adjustment of the releasing mechanism to its normal condition after the overload has subsided. In explanation of this feature the movement of the plunger I. must be under the influence of a current of C value. for a time T. and if T has not been sufficient to effect the release of the springprojccting mechanism before the value of C has fallen the breaker will not be tripped. This feature of my invention involves a principle of considerable value on motor circuits where an excessive overload frequently occurs during the starting up period for short intervals of time, the apparatus which the circuit-breaker is designed to protect being constructed with a sufficient overload factor to operate on overloads of but short duration.

In Fig. 3, the solenoid I) and its core F provided for the time limit overload. are located in lower vertical alinement with respect to the solenoid C and its core designed for rupturing the circuit on an in stantaneous overload, the core I resting upon a pedestal J, the vertical position of which can be regulated by hand adjusting means L. while the vertically movable tappet m playing in the top of the casing T). has connections with a shifting pin J for the upper core said connections including hand operable means If for adjusting the vertical position of the latter pedestal relatively to the core The inner confining chamber l) for the glycerin. has the upper and lower series of openings f*, f. the latter cooperating with the openings 12 of the upturned inner portion l) of the outer casing, in a manner corres unuling with that of the similar parts in the construction disclosed in Fig. i.

In Fig. 3. Q designates the index for in di-ating the retarding period of the time limit overload. while the index Q correspondingly serves for the adju tment providing for the strength of the current, during the interval of time for which the retarding index has been set.

The operation will be readily comprehended. Upon an excessive overload. the solenoid C will elevate its core to trip the latch P, release the motor and operate the switch, such movements being accom lished entirely independent of the solenoid 2 and concomitant parts. When the limit of the lower abnormal overload riod is reached, the core I will contact with the tappet m, raise the same and effect the lifting of the core 0 into the area of magnetic influence of the solenoid C so that said core will theninstantaneousl rise, trip the latch and opcrate the switc Having described my invention so that those skilled in the art to which it appertains could construct, apply and make use of the same, I claim as new and desire to secure by Letters Patent of the United States 1. The combination with an electric circuit, of a freel movable member for opening said circult, actuating means for said member responsive to predetermined current in said circuit and normally so related to said member that said actuatin means is unable to move said member, and means responsive to other redetermined current conditions whereby t e relative position of said actuating means and said member is varied to enable said actuating means to move the said member.

2. The combination with an electric circuit having an electroma netic coil, of a freely movable member 0 magnetic material so related to the coil that normally said member lies beyond the efl'l ctive magnetic field of said coil when the current has a predetermined value, and means for movin said member into the effective magnetic field of said coil in response to a flow of current having said predetermined value.

3. The combination with an electric circuit having an electromagnetic coil therein, of a freely movable member composed of magnetic material and normally beyond the effective field of said coil when the current therein has a predetermined value, and means including a time limit device for movin said member into the effective field of said coil under certain other current conditions whereby said coil is enabled to actuate said member.

4. The combination with an electric circuit having an electro-magnetic coil therein, of a freely movable armature normally beyond the effective magnetic field of said coil when the current therein has a predetermined value, and means responsive to current of another predetermined value for movin said armature into the efl'ective field of sai coil to enable said coil to move said member, said second means including a ma netic coil and a movable member actuate thereb a fluid containing cylinder for retarding t e movement of said latter member, re ulating means for varying the flow of flui and means for adjusting the position of said latter member with respect to its coil.

5. The combination with an electric circuit, of a freely movable member, actuating means for moving said member in response to a redetermined current flowing in said circuit, a support for said movable member, a second member operatively related to said support, and means for moving said second member and said support in response to certain other current conditions to a position enabling said actuating means to move said member under said current conditions.

6. The combination with an electric circuit, of a freely movable member, actuating means for moving said member in response to a predetermined current flowing in said circuit, a support for said member, a second member provided with a time'limit device and operatively related to said support, and means for moving said second member and said support in response to certain other current conditions to a position enabling said actuating means to move said member under said current conditions. i

7. The combination, twb electromagnetic coils, a free core for one coil, a support for said core, and a core for the other coil having a time limit device and operatively connected to said su port to change the relati.ve position of the rst core and its 0011 under certain current conditions in said coils.

8. The combination with an electric circuit, of a movable member, an electromagnetic coil in said circuit and so related to said movable member that said movable member is actuated thereby in response to a predetermined current flowing in said circuit, and means for changin the relative positions of said coil and mem er under certain other current conditions, to enable said coil to move said member to actuate said movable member in response to current values less than said predetermined amount.

9. The combination with an electric circuit, ofa circuit breaker comprising a switch and restraining means therefor, electromagneticall operated devices including a member and means to actuate it to trip said restrainin means upon a redetermined overloa of current in sai circuit, and a second member operatively associated with said first member for bringing it lnto operative relation to its actuating means under certain other conditions of overload.

10. The combination with an electric circuit, of a circuit breaker comprising a switch and restraining means therefor, an electromagnetic coil and a movable member of magnetic material so related that normallv under certain conditions of overload in said circuit'the movable member lies beyond the effective magnetic field of said coil while under certain other conditions of overload said member lies within said field,

and means for-moving said member into the effective magnetic field of saidcoil during the first of said conditions of overload.

11. The combination with an electric circuit, of a circuit breaker comprising a switch and restraining means therefor, an electromagnetic device including a movable element arranged to trip said restraining means, and means for moving said movable element into the effective magnetic field of said electromagnet under certain conditions of overload in said circuit.

12. The combination with an electric circuit, of a circuit breaker comprising a switch and restraining means therefor, an electromagnetic coil, a movable member for causing the release of said restraining means, said movable member bein normally out of the effective magnetic fie d of said electromagnet, and means for moving said member into said magnetic field upon a predetermined overload in said circuit.

13. The combination with an electromagnet and a movable member actuated thereby, of a time limit device therefor comprisin a pair of cylinders arranged the one wit in the other and having a communicating assageway, means for adjustin the size 0 the passageway, and an adjusta le support for said movable member within said cylinders.

14. In combination with an electromagnet and a movable member actuated thereby, of a'time limit device therefor comprisin a pair of cylinders arranged the one wit in the other, a communicating opening throu h the inner cylinder, and means actuated y the rotation of the other cylinder to vary the size of said opening.

In testimony whereof, I have signed my name to this specification in the presence of two subscribing witnesses.

PHILrP K. STERN.

Witnesses STEPHEN TEUcIcK, M. BLUMEB.

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