US1438789A - Releasing device for overlorad switches - Google Patents

Description

AVAIMBLE L. SCHON.

RELEASING DEVICE FOR OVERLOAD SWITCHES.

APPLICATION FILED DEC- 3. I920.

Patented Dec. 12, 1922.

//2 reg/Er Ladm' 4/ retested Dec. 12, 1922.

sTarss BEST AVAFLABLE PATENT t me;

.1 iii v IRELEASIN-G- DEVICE FOR OVERLOAD SWITCHES.

,5: v i Applica tion filed December s, 1920., Serial vno. 428,092.

,fBe i know lhat I,. Dr. Lnn wle ScHoN,

Essen-on-the-Ruhr, rermany, a

.citizen of the; German .Republic, have ina 'ented certain new and useful Improvepment'in a. Releasin Device for Overload Sw'itches fiorwhich? have filed an application in Germany January 16,1919), of which f lec isa e pe fie nv Ihis invention refersto .alreleasing device fonoverl oad switches inthecase of which an automat c, electromagnetic cutout; operating in dependenceiupon the. current intensity offthe circuit tdbe" interrupted, ;is adapted to gigadil agllyxclosezby the, actuation of a rate et gear,- closing auxiliary fcircuit,- the closing of which'in turn causes the overload switch to enter intoi function. -{fA n embQd' entpo f tl1e sub'ect matter of this inveiition is shown bysway example in the annexed drawing combinationwith an overload switch serving for the protection of a series.motoi'. a v ,Rejerri g to this drawing, A denotes the magnet coreof the overload switch provided iwithttwo exciting windingsB and C- wound to vassistfea ch other. Of these two windings the one, 13, is disposed within the main circuit contaiuing the series motor D while the .othenw'inding; C is connected in an auxiliary circuit in shunt, with the main circuit. A resistance F is interpolated between the one end of the exciting winding and a point of the niain'E connecting the main current winding B with the motor 1). .To the lower end ,of the magnet core A there is fixed a contact member a affording the possibility of bridging a brealnrlisposecl in the main circuit and consisting of two stationary core 40 tact members a and a. A spring (1 adapted to act counter. to the magnetic pull of the overload switch is arranged, to engage the contact member a The general conditions are such that the series winding Bfwill be enabled-'to open the overload switch A only at a veryconsiderable overload (short-circuit). On the other hand, the winding C, disposed within the auxiliary circuit, and the resistance F are so dimensioned that the overload switch will be opened by means .of a current traversing the auxiliary circuit while keepingclear of the resistance F, and tliag subsequently, the said overload switch A will be retained in the oii position by a current traversing in series the exciting windlng C and the resistance l.

- iwo exciting windings H and I'l are disposed in series within the main E connecting B of the overload The said two the main current windin switch with the motor- .windings'are oppositely wound ona magnet core G and are for their part so dimensioned that they are enabled to produce magnetic pulls of equal magnitude On the core G there IS in addit onarranged a third winding J short circuited on itself. The one of said exciting windings connected in series, H is adapted to besliortecircuited by means or". a

niain G provided with a break. This latter 'is composed of a rigidly disposed contact v member 5/? and a movahlecontact member fixed to the upper end of the magnet core, (i. A spring is adapted to engage the contact 'n'icinber while with its other end said s)rin 2 hears down on a'stat-ionarv )la'te r lhe exciting winding ll. is sodimensioned that when the current intensity does not exceed the normal rate its magnetic pull will not be sufiicient to overcome the power exerted by the spring g while the moment an overload current arises n the main l), the

[said magnetic pull will cause the. magnet core (r to move downwards; so that the spring 3 will be compresscd'and the break 'gJf/ in consequence opened.

A bolt fixed to the lower end of the .magnet core G-and traversing the rigidly fixed magnet armature r is provided with a pawl adapted to cooperate with a ratchet hand, to'the said arm 70 and, on the other sc'non, OY 'ssEN-ON-THE-RUKR, GERMANY; ASSIGNOR 'ro' FRIED. miner x'rmNGEsn LLscHArT, or EssEN-oN- rHE-BUHR, GERMANY.

hand, to the hearing (not shown) oi? the shaft M, which spiral spring has the tendency to rotate both the arm is" and the ratchet wheel K backwards, counter to the direction indicated by the arrow 00. The contact member k mounted on the movable arm 77 andconnected byrneans-of-a main M with the one end o f the exciting wi-ndingCo-t the overload switch, forms, conjointlywith a shear r rear aleash s-Zr cannfiatedifor f.- '1ts part y paganst a rnanr with the as as'pring p acting counter'to" the magnetic pull is ada ptedjto"engagethelotherhrm p oh? the saidlever. The' magnet and the spring p are so designed that the-magnet Q, will be enabled to nvert tome the tension of the spring "79 and therewith-the pawl {P will 1 be un to ajrres'tthe ratchet wheeliK,:o11ly -for sucha '-'length-dftiniefas the mainE is tray- Eerse'tl by an overload smear.

.Whenf considering the" manner for opersecret the, idbi iceihre iribe foref described let it befassumed that the inotiir D is runnin aha' -raking Murmur o'f normal :intensity and ifuithe'r all the parts are in the positionillustrated."In this position, the exciting winding-H short-circuited by the main G the break '9 g of which is bridged, whileboththe P, acte d upon spring 2 :and thefpaw'l g gin its turn 'acted upon by spr ng remain in consequence out of engagementwith the ratchet wheel K. The switch arm Z Il121-l11t21lllS its open position, and the break a a, a of the overload switch A B Cis bridged. The main circuit is now traifersed by a current flowing from the positiye pole of the source of continuous current supply across of, a a B.-

IT: G5 9 9 7. to the negative pole.

it now for any cause whatsoever, say, for example in consequence of the motor D obtaining a mechanical overload, the intensity of current within the main circuit should 'huppen to exceed a certain limit Without,

l ,Q YQ."- at i ng tha pa t o 'lar value a h h th c itin win ing Bof t liieuoy rad. sw tch A en rs i t fllnfition, then th m gnet Q will attraetthearnrp 0f the aul ,R a d thi latter, will-"thus come to were? t efi l t lh Kbyimea s of i ethane-U11 1 At the sam meithemagn rar aWad wnW rds by the magnetic pull e erte y. th exc ting W nding H counter to, the action of the spring g.

This downward motion of the magnet core (i opens the break, composed of the contact members 9 g and appertaining to the main G adapted to short-circuit the exciting winding H The current within the main circuit therefore now takes its course across the exciting windings H, H connected -in series. As a result, the magnetic pull exerted up to that moment by the exciting windingli onxthe -care (his, ualsized, andis further temporarily replace by the magnetic pull exerted in the same sense :iihfy the shont-icircuit winding J, in whichthere arises, when the field of the winding H is'equalizedya powerful induction current. The core G is thus enabled to complete its downward vmotion until'its makeslcontact with'the'armature g, and then returns, when the field 0f the winding J'= hasdisappeare d,' into its initial posit-ion under the action oi the'spring g In" the course of thefdownward motion ofthecore Gjust described, the pawl g engages -the-ratchet wheel K and rotates it forward-for atooth space, in the direction of meg-arrow :12. At

thesaine time the "contact niemberk fixed to the arm 70 approaches the stationary 'contactmemberk for one certain step. It is obviousthat the damping action of the winding will be all the more powerful, the greater the intensity ',of the current iwhich' his traversed" the main circuit and excited the fwinding' H. Onthe conclusion of the said. upward motion of the core Gtheconta'ctf members 9 and again make contact and the exciting winding H is again shoit-circuited. Thereupon the operation is repeated and continues while there is an overload in the :main circuit until the contact members 70 and 73 make contact. As soon asthis takes place, a current is caused to flow across the auxiliary circuit C-M Z1 k Z1 N exciting the hitherto dead exciting winding C of the overload switch A B C and resulting in the interruption oi the main circuit by breaking the contact between the member a and the mem bers a and a2 whereupon the motor D is quickly brought to a stop. As, together with the main'current, the excitation of the magnet Q, disappears, the pawl P is brought out of engagement with the ratchet wheel K and the arm 70 acted on by the spiral spring 10, returns into the initial position shown in the drawing, the ratchet wheel rotating in the direction counter to that indicated by the arrow a2. Notwithstanding, the exciting winding C still remains excited since a curient is now caused to fiow acro ss' 'l C F E QVH G g g E D w h icl 1 in View of the dimensions indicated of the resistance F, sufii'ces to retain the magnet core A in its upraised-position and counter to the action Off the spring a, so that themain circuit is now prevented from again closing. (Duly until when. after the disturbing element has been removerha hand cut-out disposed in the. main circuit (though not shown)' has been put in the off position, the exciting winding C is deprived otcurrent and the overload switch. returns into theposition indicated. The said hand cut-out being again retru-ned into the closed position, the operation may be repeated. The more powerful the overload current within the main circuit. the more rapid the motion Will be executed by the magnet core G, and as a consequence the shorter will be the duration of the individual steps of the switching operation. T he moment at which the arm A by means of its contact member is makes contact with the member 7: and thus closed the auxiliary circuit containing the exciting winding C, thus depends upon the.size of the overload prevailing in the main circuit in such a manner that a slight overload may be kept up longer than a great overload, a fact which entirely corresponds with the peculiar requirements of an intensely working motor service.

On the flow of the overload current ceasing before the contact members 71: and k have made contact then the ma net Q will release the arm p of the pawl and this latter is brought out of engagement. Hereupon, the spiral spring is draws the arm 7. back into its position of rest so that any interruption of the overload switch is not liable to arise.

In this case of a very powerful overload current, such as will arise in the course of a short-circuit, the magnet core A is immediately attracted in consequence of the magnetic pull exerted by the exciting winding l: and the main circuit thereby broken without the remaining portions of the releasing device being brought into action.

It it be desired to render variable, independent of the current intensity, the period of time passing from the commencement of the switching operation until the interrup tion takes place by the magnet core A, that may be effected by arranging the contact men'iber 7.1 to move along an arc of a circle around. the axis of rotation of the switch :lrin I11 As will be readily luidcrstoml from the foregoing description, the subjectmatter of: the invention excels in the simplicity of its c nstruction while embodying reliability oli service and the capacity to regulate the above-mentioned switching time within wide limits.

Claims.

1. An arrangement of the class described in combination with an overload switch comprising an electromagnetic periodic inteu rupter. said interrupt-er being included in the circuit to be broker. and operating in dependence upon the intensity of this circuit. an auxiliary circuit and means operatable by said interrupter for closing said auxiliary circuit step by step to cause said overload switch to function.

' 2. A device of the class described in combination with an overload switch comprising an automatic electromagnetic device connected in and operatable in dependence upon the current intensity of the circuit to be broken, an auxiliary circuit operatively connected to said overload switch for controlling the same, a step by step ratchet mechanism and a switch operated thereby for closing said auxiliary circuit, said ratchet mechanism being operatable by said automatic electromagnetic device.

3. A releasing device for overload switches comprising in combination with an overload switch an electromagnetic periodic interrupter having two series windings of equal magnetic intensity, means connecting said windings whereby when said interrupter is in closed position one of said windings is short circuited and when said interrupter is in off position said windings neutralize one another, an auxiliary circuit connected to said overload switch so as to control the same, a step by step circuit closing device for closing said auxiliary circuit and means operatable by said interrupter for operating said circuit closing device.

4. Areleasing device for use in combina tion with overload switches comprising an electromagnetic periodic interrupter included in and operated in dependence upon the current intensity of the circuit to be broken, said interrupter being provided with two series windings of equal magnetic intensity, means for normally short-circuiting one of said windings when said interrupter is in its closed position, said windings being neutralized when said interrupter is in the oil. position, said interrupter being provided with a short winding short circuiting on itself, an auxiliary circuit connected to said overload switch in such a manner as to operate the same, a switch for controlling said auxiliary circuit, means operated by said interrupter for effecting the closing of said switch, said short winding being provided for the purpose of extending the duration of the steps of the switching operation of said interrupter.

5. .A device of the class described comprising the combination with an overload switch of an automatic electromagnetic device included in and operating in dependence upon the current intensity of the circuit to be broken, an auxiliary circuit operatively connectel to said overload switch for controlling the same, a switch for closing said auxiliary circuit, a ratchet carrying the movable portion of said switch, a power accumulating member tending to retain thernovable portion of said switch in its open po- BESTAVAH The foregoing specification signed aL E5591}, G grmany, tl 11s 26th day of J uly 153211.

,IILUDWIG SGHON.

' Hays GOTISMANN,

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