US1382246A - Electromagnetic switch - Google Patents

Description

H. K. SANDELL.

ELECTROMAGNETIC SWITCH. APPLlCATION FILED APR.16, 1919.

Patented June 21, 1921.

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H. K. SANDELL.

ELECTROMAGNETIC SWITCH. APPL lCATl0N FILED APR-16, 1919.

Patented June 21; 1921.

4 SHEETS-SHEET 4.

UNITED STATES PATENT OFFICE.

HENRY K. SANDELL, OF CHICAGO, ILLINOIS, ASSIGNOR T0 HERBERT S. MILLS, OF CHICAGO, ILLINOIS.

ELECTROMAGNETIC SWITCH.

Original application filed September 11, 1916, Serial No. 119,480. Divided and this application filed.

Specification of Letters Patent.

April 16, 1919. Serial No. 290,602.

To all whom it may concern:

Be it known that I, HENRY K; SANDELL, a citizen of the United States, residing at Chicago, in the county of Cook and State of Illinois, have invented a new and useful Improvement in Electromagnetic Switches, of which the following is a specification.

My invention relates to circuit breakers, more particularly intended for use as control devices in connectionwith a synchro nously driven commutating rectifier designed for charging storage batteries. The invention will be fully understood from the following detailed description in connection with the accompanying drawings. In the drawings Figure 1 is a front elevation, partly in section, of a switch-board upon which my control apparatus is assembled; Fig. 2 is a vertical sectional view through the circuit-breaker and taken substantially on the line 2-2 of Fig. 1; Fig. 3 is a transverse section on the line 3 of Fig. 2; Fig. 4: is a detail section on the line 4: of Fig.1 and showing the gear-train for the escapement or damper-mechanism; Fig. 5 is a sectional view of the circuit-breaker similarto Fig. 2 but showing the breaker in the open position; and Fig. 6 is a diagrammatic repreyond predetermined limits; the

sentation of the entire system, showing the electrical connections of the apparatus.

,In order that the general relations and functions of the several distinct devices -which make up my control system may be better understood, reference will first be had to Fig. 6. In this figure, the letter A designates the main switch or alternating-current switch and the automatic throw-out mechanism associated with the same; the letter B designates an alternating-current relay de signed to become operative when the frequency of the alternating current varies bedesignates a direct-current relay for 'opera tion under overloads or reverse current on the D C side of the apparatus; the letter D designates a meter by which the circuit is automatically opened when a predetermined charge has entered the battery, or, option ally, when the battery has been on charge for a predetermined length of time; and the letter E designates a circuit-breaker through which the main charging-current passes and i which is automatically operable through the letter C- other control-devices with which it is associated, as will later appear. The letter F designates a synchronouslydriven rectifying-device, and the letterGr designates an inductance in series therewith. H designates the transformer which, as illustrated, is of the combined auto-transformer and double-windingtransformer construction.

The mechanical construction of the circuit-breaker is shown in detail in Figs. 1 to 5. Referring to these figures, the nu meral ll designates a base-plate which is mounted upon the switch-board 11 and carries a pair of outstanding ears between which there is pivoted for oscillation in the vertical plane a contact-arm 42. This arm has mounted thereon above its pivot-point a magnetic-metal armature-block 43 which approaches and recedes from the poles of an operating magnet 44 mounted on the upper end of the base 41. Above the armature 43, the arm 42 carries a contact-face 45, and the upper end of the arm is forked to embrace the carbon-contact block 16.

. For engaging the face 15 and carbon-block 1-6 the switch-board ll carries three distinct contact elements, all ofwhich are mounted upon a separate base 47. The lower edge of the base at has secured thereto a laminated I contact-member formed of a plurality of cop per strips 48, the outer or free ends of which are bent to insure contact between each of the strips and the plate face 15. The strips 18 are normally held in the curved position sistance carried in its outer end in position to engage the carbon-block 46. The upper end of the base. 47 carries outwardly and upwardly inclined bracket-arms 52 between "the ends of which there is journaled a carbon-block 53, a suitable horizontal pivot-pin being employed for the purpose. The block 53 is secured in a metallic base 54., to which is screwed the end of a leaf-spring 55 carried by the base 47, the spring having a set which tends to throw the pivoted block 53 upwardly. A helical tension-spring 56 has one end caught in the mounting of the block 53 and the other end secured to the swing of this escapement-gearing carries a crank arm 60 with which there is connected a link 61 having an L-shaped slot 62 in its outer end, which slot receives a pin 63 in the circuit-breaker arm 4-2. An arm 64 projects outwardly at a slight angle to the link 61 and is adapted to engage a release-stud 65 carried by the face-plate of the escapement gearing. A helical tension-spring 66 is stretched between the lower portion of the arm 42 and the link 61, in order that the link 61 may be moved to engage the angular end of the slot 62 with the stud 63.

The driving-shaft 59 of the escapement- I gearing is connected with this gearing only through a ratchet-wheel 67 (Fi 4;) with which there cooperates a spring-held pawl on the main driving-gear. Through this main driving-gear and through the intermediate gear-train illustrated, rotation of the driving-shaft 59 in clockwise direction, as viewed in Fig. 42, operates at greatly 'increased speed an air-vane 68 (Fig. 2), and it is by the resistance to motion of this Vane that the s eed of the drive-shaft 59 is held down to t e desired limit.

The extreme lower end of the arm 42 is curved inwardly and carries a laterally-projecting pin 69 which cooperates with a contact-device in the form of a pivoted lever 70 formed of metal and notched intermediate its length, as indicated by the dotted lines 71 in Fig. l, and having riveted thereto an insulating plate 72 the notch of which is shallower than is the notch in the arm itself. Th insulation 72 is cut away from the lower end to expose the metal of the arm at the outer end of the notch, as indicated at 73 in the drawing. I The circuit-breaker base 41 carries a spring leaf l2 which extends downwardly into the path of the lower inturned end of the arm 4L2and serves as a yielding stop for the same.

In addition to the parts mentioned, the

circuit-breaker construction includes two ad ditional contact-devices, one being in the form of an arm 7 L secured to, but insulated from, the upper base 47 and adapted to en gage the swinging arm 50 in one position of the latter, as shown in Fig. 2. The second contact-device is of similar construction, embodying an. inturned spring contact-finger 75 mounted on a stud 7 6 which is insulated from the circuit-breaker base 41. The contacts 75 are out of contact with the arm 4-2 in the open position of the latter, and

come into engagement therewith sometime before the arm reaches the closed position.

Th mechanical operation of the circuitbreaker is as follows: Assuming that the arm is in the open position shown in Fig. 5, all of the various contacts of the arm will be open save only the contact between the pin'69 at the lower end of the arm and the metallic portion 73 of thepivoted contactpiece 70. If the magnet 44 be now energized, the arm will be drawn toward the closed position, and in such movement the link 61 will operate through th crank-arm 60 and shaft 59 to drive the air-vane 68. Through the braking effect of this vane, therefore, the closing movement of the arm will be dampened or retarded to the desired extent. As the arm continues to move toward the closed position, th projecting portion 64: of the link 61 will engage the pin 65, and by continued movement of the parts, the link will be oscillated to free the pin 63 on the arm 1-2 from the angular end of the slot 62. The circuit-breaker arm will therefore be automatically released from the dampening mechanism and will move quickly to the full closed position. In such movement, the carhon-rod 551 will first engage the block 46 in the end of the arm, the block -l6 will next engage the upper face of the pivoted. block 53, and finally, the contact fingers 48 will engage the contact-face 45. During the closing movement of the arm the spring contactfingers will have engaged the same shortly before any of the arm contacts proper come into engagement, and the spring contacts 74 will have engaged the carbon-carrying arm fl the latter has been moved rearwardly a predetermined distance. So also, the arm approaches the closed position, and approximately at the time when the dampening mechanism is released, the pin 69 in the bottom of the arm rides oil of the metallic portion 7?; and onto the insulated section 72 of the pivoted lower contact 70.

If, through any cause. the magnets 44 should be deenergized, the circuit-breaker arm will be practically instantaneously returned to the open positiom-both through the forc of gravity and through the action of the spring contact-fingers or leaves 48 and the spring-held contact-arm 50. In the opening movement of the circuit-breaker arm the contact will first be broken between the me tallic fingers l8 and the face 45, next between the carbon-block 46 andv the block and last between the block 46 and rod 51. Through the ratchet connections between th shaft 59 and the air-vane gear-train, the circuit-breaker arm is permitted to open freely and without the resistance or braking el'iect of the air-vane.

The circuit breaker is associated with other apparatus required to make up a complete control system in the manner illustrated in rect current lines. A second shunt, designated 107 extends between. the conductor 105 and the spring-fingers 74, which bear on the lever 50 of the circuit-breaker, and in- V eludes the shunt-coil of the overload and reverse-current relay 0. The third'shunt is designated 108 and extends between the circuit-breaker base 41 and the conductor 105, including resistance member 109 in series in the shunt with swinging contact 70 which engages the bottom of the circuit-breaker arm-42. Beyondvthe juncture of the resistance-shunt 109 with the main shunt108, the

latter has in series connection the'coils of circuit-breaker magnet 44, the contact of overload and reverse-current relay 0, the contact of alternating-current relay B, and the contact of alternating-current switch A.

The operation of the circuit breaker will be apparent from the following description thereof in connection with the apparatus shown in Fig. 6. Assuming that the battery to be charged has been connected across the direct- current line 104, 105, and the l knife-switch A has been closed, the circuit breaker arm being in the open position, the contacts 74 of the lever 50 of thecircuit breaker will be open, thereby breaking currents in the shunt circuit 107 and consequently in the series magnet of overload and reverse-current relay C; The contact member will likewise have its metallic portion resting upon the arm, whereby shunt 108 is closed through this branch-circuit, in addition to being closed through the resistance 109. The full battery potential will thereby be effective through shunt-circuit 108, and in consequence the circuit-breaker magnet 44 will be energized to attract the 'arm thereof. Due to the braking effect of the air-vane before described, the arm will move slowly to the closed position, and slightly before the automatic release of the brake mechanism, the spring contacts will engage the arm, thereby closing the shunt 106 to energize the direct-current field of the rectifier. V v

The rectifier, which has been hitherto running as an induction-motor, will, by the action of this direct-current field, now run as a synchronous motor, and will, further more, automatically assume proper polarity for charging the battery which energizes the direct-current field. Almost immediately after the engagement of the contacts 75 with the circuit-breaker arm, the latter will be automatically released from its brake-mechanism and will movequickly to the closed position, the three separate, main contacts of the arm closing in the order before described. In the fully closed position ofthe arm, the contact 74 will be engaged by the lever 50. to ener ize the shunt-coil of the overload relay 6, so that the series and shunt-coils of this member, in effect, become energized at the same instant, and the armature thereof retains its normal position, closing the shunt 108.

Furthermore, by movement of the arm 42 to the fully closed position, contact is broken between the bottom of the arm and the member 70, and the shunt 108 is now energized only through the resistance 109. The circuit-breaker magnet 44 therefore draws only a very small current during the normal operation of the mechanism, the act of closing the arm serving to reduce the current in the magnet from the full value which was necessary to secure a positive closing down to the far lower value required to maintainthe arm in the closed position. 1

1 Through changes in cycles or failure of potential in the alternating-current side, or through over-load or reverse current in the direct-current side, the shunt 108 will be automatically opened, and, by the consequent deenergizing of the circuit-breaker magnets 44, the circuit-breaker arm will fly to the open position, and in such movement, the carbon contact members of the arm, which break contact after the main or metal contact thereof, will prevent arcing of the metal contacts. It should also be noted that the yielding spring-stop 42 which engages the bottom of the arm'42 will permit the latter to open a gap considerably inexcess of the normalopen gap, thereby drawing out and breaking the are between the circuitbreaker contacts. The arm will slowly return, however, under the influence of the spring 42' and against the resistance or braking effect of the air-vane 68, to its normal open position, and in such position the gap between the contacts of thea rm and between the armature on the arm and the energizing magnet maybe relatively small.

As soon as the abnormal condition which caused the opening of the shunt 108 and consequent opening of the circuit-breaker is remedied, the shunt 108 will be automatically closed, since both the alternating-currentrelay and the over-load and reversecurrent relay are capable of again automatically setting themselves when proper conditions are established. The battery voltage will therefore be effective on the shunt 108 to close the circuit-breaker again energize the direct-current field of the rectifier to bring the latter into synchronism and in general to return the parts to their normal closed charging position. This automatic operation of the system by which the safetydevices described return to their normal position without attention, I deem one of the most important features of my invention.

This application is a division of my prior application Serial No. 119,460, filed September 11, 1916, which issued as patent No. 1,329,799 on February 3rd, 1920.

While I have shown and described in considerable detail one specific embodiment of my invention, it will be understood that this 'is illustrative only, and for the purpose of making clear the nature and objects of my invention, and that I do not regard the invention as limited to these details, nor to any of them, except in so far as such limitations are included within the terms of the following claims, in which it is my intention to claim all novelty inherent in my invention as broadly as is permissible in view of the prior art.

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

1. A circuit-breaker comprising a base carrying a contact-member, a movable contact-arm pivoted to thesaid base for movement toward and away from the said contact-member, electro-magnetic means for moving said arm to closed position, a brake for resisting the closing movement only of said arm, and means for automatically releasing thesaid brake as the arm approaches the closed position.

2. A circuit-breaker comprising a base carrying a contact-member, a movable contact-arm pivoted to the said base for movement toward and away from the said contact-member, electro -magnetic means for moving said arm to closed position, ratchet brake mechanism, means for connecting said brake mechanism to the arm whereby the closing movement only of the arm is resisted thereby, and means for releasing the operative connection between the said connecting means and the arm during closing movement of the arm as it approaches its closed position.

3'. A circuit-breaker comprising a base carrying a contact-member, a movable contact-arm pivoted to the said base for movement toward and away from the said contact-member, electro-magnetic means for moving-said arm to closed position, ratchet 'brake mechanism, a link operatively connected to the said brake mechanism, means upon the arm for engaging the link, means for locking the said engaging means when the arm is in open position whereby the arm actuates the link during closing movement ment toward and away from the said contact-member, electro-magnetic means for movingsaid arm to closed position, ratchet brake mechanlsm, means for connecting said "brake mechanism to the arm whereby the closing movement only of the arm is resisted thereby, means for releasing the operative connection between the said connecting means and the arm during closing movement of the arm as it approaches its closed position, means for throwing said arm forcibly to the open position and an elastic stop for permitting said arm to substantially overtravel in its opening movement and for returning the arm to normal open position after such period of over-travel. I

5. A circuit-breaker comprising a baseportion carrying contact-members, an arm pivoted to said base for movement toward and away from said members, electro-magnetic means for drawing said arm to the closed position, means for forciblythrowing said arm to the open position, ratchet brake mechanism for resisting the closing movement only of the said arm, and anelastic stop for said arm designed to permit the same to substantially 0ver-travel in its opening movement, the elasticity of the said stop serving to slowly return the arm to its normal open position against the resistance of the said brake mechanism.

6. A circuit -breaker comprising a base carrying a contact-member, an arm pivoted to the said base for movement toward and away from the contact, electro-magnetic means for drawing said arm to the closed position, mechanical means for forcibly throwing said arm to the open position, ratchet brake mechanism resisting the closing movement only of the said arm, means for releasing the said brake mechanism as the arm approaches closed position, an elas tic stop for limiting the opening movement of the said arm, said stop permitting the said arm to substantially over-travel as it is thrown open and serving to return the arm slowly to normal open position against the resistance of the said brake mechanism.

In witness whereof I have hereunto set my hand and seal.

HENRY K. SANDELL. [L.s.]

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