US845656A - Electric-circuit controller. - Google Patents

Description

No. 845,656. PATENTED FEB. 26, 1907.

H. W. LEONARD.

ELECTRIC CIRCUIT CONTROLLER. APPLICATION FILED APR.6,1906.

7 SHEETS-SHBET 1.

PATENTED FEB. 26, 1907.

H. W. LEONARD. ELECTRIC CIRCUIT CONTROLLER.

APPLICATION FILED APR.6, 1906.

7 SHEETS-SHEET 2.

wit 2 was NC. 845,656. PATENTED FEB. 26, 1907. H. W. LEONARD.

RLRCTRIC CIRCUIT CONTROLLER.

APPLIOATION FILED APR.6,1906.

7 SHEETS-SHEET 3.

No. 845,656. PATENTED FEB. 26, 1907. H. W. LEONARD. ELECTRIC CIRCUIT CONTROLLER.

APPLICATION FILED APR-6,1906,

7 SHEETS- 311221 4.

No. 845,656. I PATENTED FEB: 26, 1907. H. W. LEONARD.

ELECTRIC CIRCUIT CONTROLLER.

APPLICATION FILED Arne 1906.

'7 SHEETS-SHEET 5.

WITNESSES. INVENTOR $0M KW ATTORNEY No. 845,656- PATENTED FEB. 26, 1907.

4 H. W. LEONARD. v

ELECTRIC CIRCUIT CONTROLLER.

APPLICATION FILED APB.6,1906.

7 SHEETS-SHEET 6.

P5,. /5 WIINESSES: INI/ENTOI? jQ/L' ATTORNEY No. 845,656. PATENTED FEB. 26, 1907 H. W. LEONARD.

ELECTRIC CIRCUIT CONTROLLER. I

APPLICATION FILED APR.6,1906.

7 SHBETS-SHEBT 7.

WITNESSES: w w M By 0 /gj/a 4 ya/ML.

- ATTORNB' UNITED STATES PATENT OFFICE.

ELECTRIQ-CIRCUIT CONTFiOLLER.

Specification of Letters Patent.

Patented Feb. 26, 1907.

Original application filed December 20,1904, Serial No. 237,653. Divided and this application filed April 6, 1906. Serial No 310,197

To aZZ whom it may concern;

Be it known that I, HARRY WARD LEON- ARD, a citizen of theUnited States, residing at Bronxville, in the county of VVestchester and State of New York, have invented certain new and useful Improvements in Electric-Circuit Controllers, or" which the following is a full, clear, and exact specification.

This application is a division of my pending application filed November 30, 1901., renewed December 20,1904, Serial No. 237,653, ranted April 10, 1906, No. 817,719, and rel ates generally to controlling-switches, and has a particular application to motor-starting rheostats or rheostats employed with electric motors or other electrical translating devices in which the resistance is employed not for regulating the energy supplied to the motor or other translating device, but mainly for gradually raising the energy at the terminals of the translating device to the full electromotive force.

My invention is also of importance where regulating resistances are used and to pre- ..vent their improper operation.

I have found in practice that such rheostats are frequently damaged by holding or ermitting the contact-lever to remain on the initial or starting contact or contacts near the same with all the resistance of the rheostat or a considerable portion thereoi in circuit. I have also found that operators rrequently close the circuit at the initial or starting contact of the rheostat and then return the lever to the idle position, this drawing an arc at the initial contact. This also damages the rheostat. I have also found that operators sometimes close the main circuit when the resistance-controlling device, which might be used as a regulator, is in an intermediate position. This of course allow s an excessive and damaging flow of current.

The main object of my invention is to devise a starting rheostat or controller or to provide the present type of starting-rheostats with a controlling device which will prevent this improper handling of such rheostats. I have devised many ways for carrying out this object both mechanically and electrically.

The full-torque current is the current which the motor takes when developing its full-rated horse-power. In starting any motor it becomes necessary to produce a torque larger than that due to the lull-tor ue current, because the motor and the load ave to be accelerated and during the period of acceleration a larger current will be required than that necessary ayter the motor has been accelerated to full speed. In the manufacture oi motor starting rheostats it is common practice to have such a resistance in the rheostat that the current which will flow when the motor is at rest and the first contact is made at the rheostat will be 'li.ty per cent. larger than the current taken by the motor when producing its normal l'ull torque. In other words, this starting accelerating-current is fifty per cent. larger than the fulltorque currentthat is, it is one hundred andlhty per cent. or the full-torque current.

In order to prevent the burning at the initial contact of the rheostat, due to the closing of the circuit upon insullicient surface or due to the backward movement of the contact-lever after making tlli) first contact, which results in the formation of an are, due to the full clectromolive force and one hundred and 'lifty per cent. of the full-torque current, (when the motor has no counter electromolive force, )the rheosl at should be pro ided with an auxiliary switch by which the circuit is quickly closed upon an ample S111 face, and which switch will open the circuit with a snap action when the contact-lever is re turned to the initial position. This auxiliary switch should be beyord direct hard control in opening and may be mechanically or electrically controlled by the rheostat contactlcver or controlli.g-switch.

In one form the rheostat contact-lever may be arrangcd to start a spri11gactuatcd auxiliary switch wliich closes or opens with a snap aciion when the rheostat contact-lever is moved forward or backward at tlzestarti g position. In some iii stances this switch may be a small one wliicli either opens ,or

closes another circuit and thereby energizes a large quick-acting circuitbreaker. In such an arrangement the small switch need not be quick actirg if it opens or closes the circuit to the coil of an automatic circuitbreaker whose current is very smallas, for

instance, in the case of a winding connected with the full electromotive force, with or without resistance, in series therewith. In

opening or closure of a circuit control! ad byother arrangements the auxiliary switch may and at its full force, or by the energization' or deene'rgization of a magnet to give the resultlng ,quich action to the switch moved thereby.

In my original application I have disclosed two formsof my invention in which the auxiliary switch is mechanically controlled. The present application relates more particularly to forms in which the control of the auxiliary switch is by electrical means.

My invention includes various other improvements and advantages, which will be understood from the following description and accompanying drawings.

In the accompanying drawings, Figure 1 is a diagrammatic view of one form of my invention. Figs. 2, 3, 4, and 5 are similar views of a modified forms of Fig. 1. Figs. 6, 7, and 8 are diagrammatic views of a modified form in which the initial movement of the rheostat-lever controls a loop-circuit con taining a solenoid which in turn controls one coil of a circuit-breaker employed with the rheostat. Figs. 9 and 10 are diagrammatic illustrations of an arrangement in which the auxiliary switch is electromechanically operated. Figs. 11 to 16 are diagrammatic views of modifications, and Figs. 17 and 1S are perspective views indicating the construction of certain parts.

Referring to Figs. 1 and 2, there is mount ed on a suitable base (not shown) a series of contacts a, to which the sections of the resistance a are connected. This resistance,

it will be understood, is arranged in any suitable manner beneath the base or within a .casing, and the sections of resistance will be insulated from each other and in some instances provided with means for absorbing the local energy developed therein. B is a switch in the form of a rheostat contact-lever pivoted on the base. In this form of my invention the movement of the rheostatlever B controls a coil which actuates a plunger to trip a spring-actuated switch, and which switch may be one element of a double-pole circuit-breaker.

The auxiliary switch of Figs. land 2 is an automatic circuit-breaker of the type shown in the patent to Leonard and Ball,- No. 705,102, granted July 22, 1902. In Fig. 1, G and G are independently-movablc switches cooperating with stationary contacts, be

tween which is connected an overload-coil H, said switches and coil being connected in series between conductor P and the con tact-lever B. The contact-lever carries a' switch B of the leaf-contact type, which bridges-two stationary contacts a: and ac when the lever is in the final position. Contact as is connected by a wire with the upper.

contact offswitch G, and contact 00 is connected by a wire with the final contact a of the resistance, so that while lever B is at the initial or any intermediate point the circuit to the armature of motor M from switcli G will be through lever B and resistance a to contact as, the motor-armature being connected between the latter contact and conductor N. The field of- M is connected in series with underload-magnet F between the initial contact a and conductor N, the field and armature windings being in shunt relation.

It will be seen that when lever B is in the final position the armature-circuit of the motor will be through switch B, which makes very intimate contact at a; and 0:, the resistance being shunted out of the armature-circuit. With motor-starting rheostats it has been customary to provide spring-contact clips for the rheostat-lever at the final position, as shown in Fig. 2 of my original application, to afford good contact and prevent heating, which would happen if a contactbutton were employed for the final contact. With those spring-clip contacts, however, I have found it necessary to employ a hammerblow device for the contact-lever to start the same when an automatic release is provided to control the circuit. With a leaf-contact switch, as shown irf Figs. 1 and 2, a ham1nerblow device is not necessary. The springbrush affords good contact and no undue heating occursfand when the automatic release responds to abnormal conditions in the circuit the action of the leaf-contact assists the spring of the contact-lever to return it to the starting position. Switch G in this form serves as the auxiliary switch and its opening movementin response to the backward movement of the contact-lever at the initial position is controlled by fine-wire coil H, which is connected between conductor N and a stationary spring-contact m which makes contact with lever B while in the initial position. The effect of this connection is to cause coil H to become energized and actuate its core or plunger, which when raised trips the catch which holds switch G closed and allows that switch to open, thus opening the circuit to the rheo'stat and motor. By referenceto Fig. 1 it will be seen that so long as contact-lever B remains in the position shown, or whenever the lever is returned to tl" at position, the high-resistance winding H will he energized by the full el ectro motive force, and switch G will be opened. In operating the controller switch G is first closed, and then G is closed immediately will be tripped by reason of the cross-piece 7&2

after the initial movement of lever B, which and then switch G is closed.

located in the same side of the circuit, while breaks the connection at contact 23*, or switch G is closed before lever B is moved and held until the latter is moved to the first resistance-contact a, or switch G is first closed, then lever B is moved to the first resistance-contact, breaking contact at at",

If the operator returns lever B after the initial movement, the circuit will immediately beopened at switch G with'a quick snap action, thus preventing the drawing of an arc. in Figs. 1 and 2 the first resistance-contact c is connected by a wire with the initial contact, so that the circuit is never opened at the rheo stat, but the resistance can never remain in circuit while the lever is in its initial position. In this form lever B is provided with the usual retracting-spring for returning it to the starting or initial ,position. It will be noticed that in Fig. 1 switches G and G are in Fig. 2 they are in opposite sides of the circuit, thus providing a double-pole switch. This is the only difference between Figs. 1 and 2. In each of the different figures when the plunger of coil 11 is raised the latches holding switches G and G will both be tripped, as is customary in double-pole circuit-breakers and as in the Leonard and Ball patentabove referred to. The construction of a suitable automatic switch is indicated in Fig. 17. Here each switch G G is shown as carried by the pivoted part 9 and each part having a handle for manual closing. Each part 9 has a projection 9, adapted to be engaged by a latch g for holding the switch in a closed position. The latches g of both, switches are controlled by the coil H and its core it. When the core is raised, due tothe large current passing in coil H, both latches engaging the extensions g 9 connected to the latches. The switches will then he opened, as by the force of springs g and the rods 9 since the latter are drawn outward by the tension of the springs, and which rods engage the surfaces 9 on the switches. When the current in coil H causes its core 71/ to be raised, its cross-piece 7L3 will engage the extension g which latter is connected to the latch g of switch G. The switch G will therefore be opened by the passing of current in coil H.

Instead ol'- connecting coil H directly to conductor N it-might in some cases be connccted to an intermediate point in the circuit, which would give suiliciently high voltage to operate the plunger of coil ll. Fig. 11' illus trates one such modification, being similar to Fig. 2, except that one end of coil H is connectcd to a point in the series of resistances. In this case the coil depends for its operation upon the drop in electromotive force on a portion of the resistance.

Referring now to Fig. 3, it will be seen that switches G G and coil H are connected in circuit in the same manner as in Fig. 2; but high-resistance coil H is connected across circuit P N in series with a high resistance. A thermostatic switch T is connected across the terminals of coil H, so that when contact is made at the platinum points coil H will be short-circuited and its core or plunger will drop, tripping the latch which holds switch G and permitting its spring to throw it open. To actuate thermal strip T, I provide a small electric heater T, which may be a pottery tube having a resistance wound thereon, as shown in my Patent No. 691,949, granted January 28, 1902. This heater is connected around all or part of the resistance of the rheostat, as shown, and it will be seen, that since the heater when lever B remains on the initial rhcostat contact will be in the armature-circuit oi the motor M across the line P N its temperature will rise rapidly, causing thermal-switch T to short-circuit coil H and open the circuit between the rheostat-lever B and conductor P.

in operating the controller of Fig. 3 the operator first closes switches G and G and will see that the core or plunger of fine-wire coil H is raised into the coil. The closure of switches G and G gives a full field to motor M and closes the armature-circuit through the entire resistance of the rheostat. The drop on the resistance 0 causes heater T to heat 11 and it lever B-is allowed to remain in the initial position the heat of T will in a predeterminable time cause the thermostatic switch T to close the shunt around coil H, thus demagnetizing that coil, whereu on its core drops and trips the latch which ho ds switch G closed. The movement oi switch G through its actuating-spring opens the circuit to the motor and rheostat. An overload-current will cause the coil H to raise its core and trip the latches holding both switches. If an abnormally low or no voltage condition exists, coil ii. will be too weak to hold its core, and switch G will be opened. An arrangement of the parts for such an operation of switches G G is indicated in Fig. 18, which is similar to Fig. 17, except that the parts are so arranged that the falling of core h -causes the opening of switch G instead of the raising of core 72 The cross-piece 71- of core 72 in falling will engage the extension 9", connected to latch g", and cause the latch to be moved, so that the switch G will be opened.

Various arrangements might be devised for heating the switch T when current flows through the resistance, and the switch T might cause the coil H to be denergized in other ways. T in proximity to'a' part of the resistance a, which resistance will serve to heat the switch if the arm B is held in position on the resistance-contacts an objectionable length of In Fig. 12 I have shown switch series with coil H and is adapted to open the .circuit of this coil when heated instead of shunting the same, as in the case of Fig. 3.

Another modification is shown in Fig. 13, in which the thermostatic controlling-switch T is connected in series with resistance a and heated. by the current passing through a, and if this resistance .2 any part thereof'is kept in circuit an improper length of time it will cause the thermostatic switch T to be heated to such a degree that it will move and force the insulated conductor is to engage the contacts 7c and short-circuit coil H. The coil H is thus demagnetized, and the dropping 'of its core will cause the main circuit to he opened at switch G. hen the resistancecontrolling arm is in final position, the thermostatic switch is cut out of circuit.

Instead of a thermal strip T for controlling the action of coil H a resistance T of iron, nickel, or other material having a high temperature coefficient, might be connected in series with coil H across the line, as show 11 in Fig. 4. In the arrangement of this figure the circuit through coil H is closed by the closing of switch G, and when the rlieostat-lever B is moved to engage the initial resistance contact the motor will start and begin to accelerate. After being held there a proper length of time the lever will be moved along the starting resistance contacts, thereby disconnecting the initial resistance contact from the first contact which originally actuated coil H, and this coil is then placed in series with the resistance T. If the rheos$at-arm B is left for an improper length of time *on the starting resistance contacts, the magnetism of coil H,'due to the gradual increase in resistance of T onaccount of being heated by resistance a in close proximity to it, would gradually become less as the time interval increased, and in a predeterminable time the core or plunger of that coil would drop and trip .the catch which holds switch G closed, whereu on that switch would open.

Another modi 'cation of this idea is show n in I ig. 5, in which a resistance T, which may be mounted 'on a pottery-tube, as in Fig. 5, is placed inside of rying a resistance T of iron, niclel, or other material having a high temperature coefficient. In this arrangement coil H and resistance 'I are connected in series across the line, and heater T is connected in a shunt around the resistance a of the rheostat, as in ig. 3 and for the same purpose. separating, the resistance T and T 2 they might be arranged upon the same support and suitably insulated. To predetermine the time interval at which the condition of coils T and T would cause the coil H to re lease its plunger,'an adjustable resistance might be provided for heater T, or w hen the windings of T and T are on separate su'p a second pottery-tube car- Instead ofports the distance between them or the rela-- two positions of one within the other might be varied to vary the heating effect of T upon T Various other ways of'regulating the action ofT and T and H in the arrangement of Figs. 3, 4, and 5 might be devised without departing from the main feature of my invention. I

In Figs. 6 and 7 the coil H is controlled by an automatic switch. In Fig. 6 this coil is connected across the circuit in series with the automatic-SW itch and a resistance, while in Fig. 7 the coil and automtic switch are connected in series with the rlzeostat. The automatic switch is preferably a double-arm switch S and s, pivoted on a common ivot and provided with a spring tending to t row them toward each other. Switch S makes contact with a spring-clip connected with coil H and which clip holds it in position, while arm 8 malres contact with a button connected to conductor N. This arm is held by a'latch s, which is tripped by the action of the core orplunger of coil S. Arm 8 is not provided with an a crating-handle and is arranged to be moved onto its contact by arm S. The coil S for controlling this switch is connected across the first resistance contact of the rlieostat and a blind initial rheostatcontact. i

It will be noted that the starter of Figs. 6 and 7 has no open-circuit point. To start the motor or'other translating device,tlie o erator first closes the switch G,then sw-itc 1- arms S and s are closed, and then the operator holds down the plunger of coil S and closes switch G. It will be seen that when this is done the circuit connections will be as indicated, that' coil S is energized, and that if the operator permits lever B to remain on the initial or blind contact and lets go of the plunger or coil S that plunger will release sw itch-arm s and'open the circuit of coil H, which in turn w ill drop its plungerand effect the opening of switch G and the circuit to the rheostat and translating device. If the operator moves lever B to its final position,

as he should do, it w ill be seen that the circuit to coil S is opened the instant lever B leaves the initial contact and that switcharm 8 will remain locked until lever B is returned to its initial position, whereupon coil S becoming energized will act as above stated. After lever B is moved from its initial position the rheostat and translatin device will. be protected against abnormal conditions in the circuit .by switches G and G Instead of connecting the auxiliary switch of lwigs. 6 and 7 as shown it might be arranged to-close a normally open shunt around coil H. This is shown in Big. 14. When current passes through the coil S, its core is raised and the switch carried thereby closes the shunt around coil H. .Its core then drops and opens G.

IIO

coefiicient.

. of negative temperature coefficient.

an arrangement when the carbon becomes its resistance due to its-high tempcraturecoefficient and send an increasing current through coil S. This is illustrated in Fig. 15, the resistance T having a high temperature When predeterminable current passes through coil 8 and raises its core, the switch in circuit of H is opened.

Instead of such a resistance a time-fuse might be employed, wh.ch when fused would cause the current to flow through S. This starting-current a predetermined lengti of time.

A still further modification is shown in Fig.1

8, where coil S is connected as a shunt on the entire or part of rheostat resistance a in series with a carbon resistance S or other material In such heated a greater current will flow. in the shunt and actuate coil S to release its switch and open or close a circuit, as above explained, to control coil H, which may be connected in either of the ways suggested.

In Fig. 9 I have shown an electromechanically-operated auxiliary switch the-action of which is governed by the movements of the rheostat-lever at its starting positions. C is a pivoted knifeswitch bla ;ie; c 0, contactjaws, as in Figs. 1 and 2 of my criginal appli-' cation. D is the actuatinghammer, which in this instance is started by solenoids O and 0', whose cores are connected to the arms of the hammer, and d is the spring for throwing the hammer after it passes the center of equilibrium, although in this arrangement the spring might be dispensed with, since the movement of the cores Will be very rapid and move with increasing speed. connections are from conductor P to switch 0, to lever B, resistance a and motor M to conductor N, the field of M being in a shunt from lever B around the resistance and motorarmature. Coils O and 0 are connected in shunt relation between contacts 0 and 0 and conductors P and NI Contacts 0 and 0 are located adjacent to the first and seconu rheostat-contacts a, respectively, so that in the initial position lever B will bridge the first contact 0, and contact 0 and in the second position contact 0 and the second contact a will be bridged. The effect of this is to connect either cell 0 or O in circuit, and, as shown, coil 0 is in circuit and its core is drawn down and hammer D is tilted to the The circuit right, closingswitch C. If lever B is returned to its initial position, coil 0 will be cut out and coil 0 cut in, thus actuating the core of the latter to throw the hammer to the left and'open switch 0. W hen lever B is moved to'its final position, both coils will be cut out of circuit and spring (i will hold switch C in position. A-mooiiication of this arrangement is shown in Fig. 10. Here only one coil 0 is employed, and this coil is connected between concuctor P and a contact o ,with which the insulated short arm b of lever B makes contact whenin contact with any of the rhetstat-contacts a from the second tothe final contacts, bu. not when in contact with the initial contact. Switch C (shown as a brush-switch) is provided with a rod 2, which breaks the are on carbon contacts .2. This switch is mountedona vertically-sliding rod 2 provided at its upper end with a stirrup 2 within which works a foot 0 securedto the lower end of rod 0 projecting from the core or plunger of coil 0 The vertically-sliding rods 2 and 0 work insuitable guides, and the lower end of rod 2 is rectangular and works in a correspondingly-shaped bearing to hold switch 0 in alinement with its stationary contacts.

As shown in Fig; 10, the rheostat-lever B is in its second position, and the circuitto coil 0 is CltSGCl and its core is drawn up and switch C is closed. If new theioperatorreturns lever B to the initial position, coil 0 will become demagnetized and its plun er will drop, striking a blow to the stirrup, t e force of which and the tension of the brusl1- switch will drive the switch downward and open the circuit to the rheostat and motor. W hen the lever Bis moved forward, closing the circuit again at contacto the plunger of coil 0 will rise, and through the engagement of foot 0" and stirrup 2 switch U will be both the armature and shunt-winding is opened by means of the automatic switch in the main circuit; also, that when the circuitis opened the armature and field are closed on themselves, giving a closed circuit for the field discharge.

Where I have referred to controlling means in the claims, it will be understood that this includes indirect as w ell as direct control.

It is evident that my invention may be embodied in various forms of construction and that I am not limited in the scope thereof except as indicated in the following claims.

Having thus ceseribed my invention, I declare that what I claim as new, and desire to secure by Letters Patent, is

1. The combination of a rheostat having a stantially all. ofthe resistance is in circuit.

2. The combination of a rheostat having a movable element for varying the resistance, a sw itch in series therewith, mechanical re straining means for holdingsaid switch in; closed position, and electroresponsive-means fbrreleasing said restraining means to automat'ically control" the opening of said elect-roresponsive switch, said means being-operated by the movement of'said element at, the inij tial position of said element.

3; The combination of 'a rheostathavinga movable element for varying the resistance, a switch in series therewith, mechanical? restraining means for holding said switch in! closed osition, electrores onsive means forcontrol ing; the release said. restraining "means to automatically control the 0 ening offsaid switch, and: means for closing t e cirof said electroresponsive means by the movement of said elementand t'herebycontrol the opening of said switch.

4'. The combination of'a rheost-at havinga 'movable element for varyingthe resistance,

a in. series therewith, mechanical restrainingmeans for; holding said switch in clbsedi sition, electromagnetic means for control'ing the; release of said restraining means to automatically control the opening ofsaid, switch, and means for closing the 'circui'tof said electromagneticmeans carried] by' said! element.

movable elementforvarying the resistance, a switch in series therewith, mechanical re-- straining means for holding said switch in closed osit'i'on, electromagnetic means for control ing the release of said restraining means to automatically control the opening; of'said switch, and means operated by sakt element at its initial position for closing the of" said electromagnetic means andl thereb control the'opening of said switch.

6. The combination of a rheostat having a movable element for varying the resistance, a switch in series therewith, mechanical Ire-- strainingmeans for holding said switch in closed position, and means comprising am y electromagnetic device for controlling the release of said restraining means for effecting the opening of said switch, said second-- named means being operated when s'aiclelementatthe initial'position to cause the current-flowto be interrupted at said switch.

7. The combination of'a rheostat having a movable element forvarying the resistance,

straining means for holding said switch in closed position, and. means comprising an electromagnetic device for controlling the release of' saidrestraining means for effecting the opening of said switch to interrupt the current-flow, said device being actuated by the movement of said element when substantially-allot said resistance is in circuit.

8'. The combination of a rheostat having a movable element for varying the resistance, said element having means whereby the element may be moved manually, a switch in series therewith, a no-voltage-device for retaining said element at its final position after being-manually moved to said position, and

'eleotnomagnetic means for controlling the openingof said switch, said means being controlled by the movement of said element.

9. The combination of a resistance having a movableelement for varying theresistance,

said element having means whereby the element may be moved manually, a no-voltage device for retaining said element in its final position after being manually moved to said position, a switch in series with said resistance, electromagnetic means for controlling the opening of said switch, and means en gaged by the movement of said element to the initial position for closing thecircuit of 1 said electroma netic means.

10; The com ination of a resistancehaving -a movable-element for varyingthe resistance, two independently-closable switches in series with each other and with said resistance, means for controlling the opening of both of said switches automatically when excessive current flows, and means operated by the movement of said element for controlling V 'the opening of at least one of! said switches. 5; The comb'nation: ofa rheostat having a ing a movable element for-varying the resist- H. The combination of a resistance havance, twoindependently-movableswitchesin series with each other andwithsaid' resistance, means for opening said switches automati'ca-lly upon the occurrence of overload, and means affected by the movement of said element for controllin the movement of at least one of said switc es.

12-. The combination of" a circuit-breaker comprising twoswitches in series with each other, an electric motor, a controlling vari the movable-element oi said rhe'ostat for protecting the circuit from abnormally low vola switch in series therewith, mechanical re tage, two independently-movable switches in IIO ing, means comprising an electroresponsive winding energized by a current independent of said armaturc-crrrent and of said fieldcurrent for controlling said switch, and a motor-rheostat having a movable element for varying the resistance, the said element being arranged to affect the current in said 'electroresponsive winding after the resistance of said rheostat has been placed in circuit and thereby control the opening of said switch.

15. The combination of a constant electromotive-force-supply circuit, a branch circuit connected across said supply-circuit, said branch circuit containing in series a motorarmature, a variable armature-controlling resistance having a movable element and an automatic circuit-breaker, said circuitbreaker comprising two independently-movable switch elements in series with each other in said branch circuit, and means for aiiecting said circuit-breaker by the operation of said element.

16. The combination of a constant electromotive-force-supply circuit, a branch circuit connected across said supply-circuit, said branch circuit containing in series a motorarmature, a variable armature-controlling resistance and an automatic circuit-hrsalter, said circuit-breaker comprising two independent] -movable switch elements in series with each other in said branch circuit, and means for protectively relating said variable resistance and at least one of said switch elements of the circuit-breaker.

17. The combination of a rheostat having a movable element for varying the resistance, a quick-acting switch, means for elcctr" wally controlling the opening of said switch by the movement of said element, a no-voltage magnet for holding said element in its restrained position, and automatic means ior controling the opening of said switch upon a predetermined current-flow.

. 18. The combination with a resistance having a movable element for ,-.o11trolling said resistance, of an automatic circuitbreaker in the motor-circuit,a control-coil for the Gil'Clllt-l)X'(.tl((l, and a contact-at or near the initial position of said element for energizing said coil.

19. The combination with a motor-r1100 stat, of a circuit-breaker, a circuit-closer on the movable element 01 said rheostat, and

' means whereby said circuit-closer controls the operation of the circuit breaker only when said element is in its initial position.

20. The combination with a motor-rheostat having a spring-pressed arm, a 0011 for controlling the circuit, a contact at or near the initial position of said arm for afi'ecting the current in said coil, and restraining means for said arm at its resistance-all-out position.

21. The combination of a motor-rheostat having a movable element for varying the resistance, two switches in series with each other and with said rheostat, eleetroresponsive means for effecting the opening of one or both of said switches upon predetermined current-ilow, ano-voltage protective device, and a contact controlled by the movement of said element for effecting the opening of one of said switches.

22.. The combination of a constant electromotive-foree-supply circuit, an electric motor, an armature-rheostat, two mechanic ally-related switches, said rheostat, switches and armature of said motor being all in series with each other in a branch circuit across said supplycircuit, means for controlling the opening of either of said switches upon overload-current passing through the armature independently of the position of the other of said switches, means for protecting the armature against conditions due to no voltage, and means for affecting at least one of said switches by said rheostat.

23. The combination of a motor having a field-winding energized independently of its armature-current, two independently-movable mechanically-relatcd switches in series with each other and with the motor-armature, means responsive 'to overload-current for automatically controlling the opening of each of said switches, a starting resistance in series with the inotor-ari'nature, means for cutting out the resistance during the start n period, and means for short-circuitmg said latter means after said resistance has been cut out.

24. The combination of a motor having a field-winding energized independently of its armattire-current, two indcpcndently-movable mochanically-relatcd switches in series with each other and with the motor-armature, means responsive to overload-current l'or antomatically controlling the opening of each ol said switches, a starting resistance in series with the motor-armature, means for cutting out the resistance during the starting period, means for sluwt-circuiling said latter means after said resistance has been cut out, and means for protecting the motor-armature upon the occurrence of no volta e.

2F The combination ol an electric motor having a field-winding energized by current independent of its armature-current, a re-- sistance adapted for only temporary passage of the full-load current for starting the motor, an automatic protective switch inseries therewith and which switch also controls the field-circuit of said motor, -electrical for reta ning said element in its nornositi a a ain a c nst yforce, 'an electric motorhaving its armature- 2o, m ser es with said element, a su ltch in series said element and motor armature to. open and close the armature-cirwhich, switch also controls the fields circuit, electromagnetic -means for opening thecircuit of. the armature when said switchv closed if excessive current then passes, and; electrical means for protectively relatings itch. and element.

2Z. 'Lfhc, combination of an, electric motor, acontrollingresistance. having a hand-operatedi moxeb e.e ment n e yi g th once, a switch in. series with the armature of said motor and; which switch, also controls the field cincuit of. the motorb an electroresponsive windingior controlling the 0 ening of said; switch-, and meansfor control mg the current said; winding so as to control the opening said, switch nlywhen said element is n such position as to nclude said resistance in the armjat ureoircuit, said element and said switch beingmechanically independent during theclosureof, said switch;

- The combination of constant electrornotlve forceesupply mains, an electric motor haying a field wlnding energized independently 0f the working armature-current, a controllingresistancefor the motor, (301111801 trons forming a, permanently-closed localloopinclnding' the motor-armature, said resiste se andfic d-w n g, a a to p. 1 tectirve switch, said, local loop and said switch, being connected in series with each othenacrosssaid mains, an clectroresponsivc winding tor controlling the motor-armature c rcuitundercertain conditions, and a branch circuit across said mains in parallel Wlth said loopv and passing through said switch, said branch containing said electrorespons ve Winding.

a 29. The combination of a resistance having a movableelement for'varying the resistance, a switch capable of, independent mo, eme it relative i to said. movable e n electrical means for controlling said switch, said means being controlled by said element, and an electromagnetic winding which independently of said means controls theopening pendent movement relatively to said first.

switch, electrical means for controlling said second switch and controlled by sald movable element only when said element ism. a

circuit-protective position, andiindependent electrical mcans for controlling the protection of the circuit .upon overload.

31. The-combination of an electric motor, two switches in series with each other and with the armature of said motor, said switches being independently movable, electroresponsive means for automatically controlling the movement of said switches,1ade- 'v ce in series with'the motor-armature for controlling the electromotive force on the terminals of the motor-armature, and electrical means functionally related to said device for causing the automatic rotectiue under certain conditions. 32. The combination of a translat ng devicein. series therewith across a normally constant elect'romotive-force circuit, said device being ada ted to vary the electromotive force u on sai translating device, two protective y-related switches in series with each other and with said'translating device, an elcctrorcsponsivc device responsiue to abnormal variations of electromotive: force upon said circuit, means for automatically controlling the movement o at leastone of said switches when an excessive current passes through the translatin device, and electrical means for protective y controlling at least one of said switches when the electromotive-force absorptivedevice is ina cer tain condition.

33. The combination of an electric motor, a resistance-controlling switch. in serieswith the armatdre of saidmotor, a functionallyrelated automatic switch in series with-said armature and said first-named switch, and means for automatically controlling the circuit when no voltage occurs, when overloadcurrent occurs and when the operator manu-.

ally controls one'of said switches, said means compiisi'ng -three electromagnetic windings each of said windings being adapted to perform its function independently of the other two windings. 34. The combination of an electric motor,

a resistance-controlling switch in series with t a ur o s id moto a unctionallymovement of at least one ot sai switches I vice, an clectromotive-force absorptive derelated automatic switch in series with said netic windings functionally related to said armature and said first-named switch, and device. 10 means for automatically controlling the cir- In testimony whereof I affix my signature cuit when no voltage occurs, when overloadin the presence of two witnesses.

current occurs and When the operator manu- H. WARD LEONARD.

ally controls one of said switches, said means Witnesses:

comprising a mechanical restraining device L. K. SAGER,

for one of said switches and two electromagl GEO. A. HOFFMAN.

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