US2181351A - Controller for electric welder and other circuits - Google Patents

Description

Nov. 28, 1939.

CONTROLLER FOR ELECTRIC WELDER AND OTHER CIRCUIT 5 c. STANSBURY 2.181351 Filed May 2, 1935 Patented Nov. 28,, 1939 PATENT OFFICE UONTROLLEI E FOR ELECTRIC WELDER AND QTHER CIRCUITS 'Cai-mll stansbury, Wauwatosa, Wis, assignor to Cutler-Hammer, Inc., Milwaukee, Wis, a cor- I por'ation of Delaware Application May 2, 1935, Serial No. 19,405

I '14 Claims.

This invention relates to improvements in controllers for electric circuits, controller-s embody-"- ing the invention being particularly advantageous for electric weldersr The invention has among its objects to provide for electric welders and other electrical deed thereby.

Another object is to provide a controller utilizing a timer of the inductive time limit type to minimize the required moving parts and contacts. 1

Another object is to provide a controller which may be built to afford either definite timing or timing subject to an influence of the welding circuit.

Another object is to provide a controller which may be built to function only once for a single manual operation, or repeatedly in response to a single manual operation and which may be built to afford either type of control at the option of the user, through the medium of a simple selector device.

Other objects and advantages of the invention will hereinafter appear.

The accompanying drawing illustrates certain embodiments of the invention which will now be described, it being understood that the invention is susceptible of various modifications without departing from the scope of the appended claims.

Figure 1 shows diagrammatically a controller providing definite timing, which controller functions only once for a single manual operation.

Figure 2 shows diagrammatically a controller providing for influence of the timing by the welding circuit, which controller may be set' to function only once or repeatedly in response to a single manual operation.

Figure 3 shows the controller of Fig. 1 with the addition of a feature desirable in some instances.

Referring to Fig. 1, the same shows diagrammatically a welder comprising welding jaws I and 2 to be supplied with current by a transformer 3. this transformer comprisinga primary winding 4 and a secondary winding 5, the latter being connected to the jaws l and 2. mary i din or the t a s m is u p d with The pricurrent from A. C. supply lines L I., through an electromagnetic contactor 6 which is biased to open position and which is to be energized in response to closure of a manual push button switch I to complete the welding circuit and to 5 be deenergized to interrupt the welder circuit after lapse of a given time,

The timing'means shown in Fig.- 1 comprises an electro-responsive relay 8 having a pivoted armature 8, normally bridging contacts 60 and H in circuit with the winding of contactor 6, said relay having a winding l2 to attract the armature away from said contacts and a winding 13 to co'act with an extension of its armature to hpldthe armature against attraction by winding I2 while the winding l3 exerts a given magnetic pull. In general design this relay is similar to an inductive time limit switch commonly employed in controlling electric motors to afford a time element incident to the commutation of the motor effected by the switch. The winding 12 of this relay is adapted to be connected directly across lines L and L by the push button switch 1 upon closure thereof. The restraining winding l3 of this relay is connected to points I4 and I5 of a closed loop containing rectifier elements l6, l1, l8 and I9, said loop being connected at a point 2|] to line L and at a. point 2| to line L through the winding I2 of relay .8 and also through the winding of contactor 6 in parallel with winding !2. The rectifier elements may be of the copper oxide type or of any other preferred type, the same being so arranged as to rectify the alternating current supplied to the loop whereby the relay winding I3 is supplied with undirectional current. The circuit of the winding l3 has included therein an adjustable rheostat 22 for a purpose hereinafter set forth.

With the contactor l5 positioned as illustrated the welder circuit is interrupted. The loop containing the rectifier elements being permanently connected across lines L and L undirectional current is supplied to the restraining winding IQ of relay 8 and since point 2| is connected by conductors 23 and 2 through the winding [2 of relay 8 by conductor 25 to line L and by conductors 23, 26 and 27 through the winding of contactor 6 by conductor 28 to conductor 25 a certain amount of current flows through the winding l2 and the contactor winding but this current is insufiicient to influence the position of the relay or to cause response of the contactor.

Upon closure of push button switch 1 circuit is completed from line L through said switch b conductor 26 through the relay contacts ll 55 and ill by conductor 27, through the winding oi contactor ll, by conductors 2t and 25 to line L Completion of this circuit causes the contactor ii to respond to complete the welder circuit and hence to initiate a welding operation. Also closure of switch Tl completes circuit from line L through said switch, by conductor E l through thewinding [12 of relay ti, by conductor 25 to line L? and accordingly the relay tends to respond. The contacts Ml and ll of the relay are included not only in the energizing circuit oi contactor b but in'a maintaining circuit for this contactor and winding l2 which is provided to maintain the contactor and winding l2 energized while the relay remains in. circuit closing position regardless of whether or not the push button 71' is held depressed. This maintainin circuit extends from line L by conductor 29, through normally open auxiliary contacts 8 of contactor by conductor St to conductors 2d and 2b which lead to the winding l2 and the con= tactor winding respectively. The relay 8 now tends to respond to disengage contacts lift and i ll but is restrained by the winding U3. On the other hand, depression of push button switch I completes a circuit paralleled by the auxiliary contacts b of the contactor, which circuit shortcircuits the rectifier loop from which the windin i3 is supplied. This short-circuit may be traced from point 2b of the loop to line L through the push button switch l, or alternatively through the auxiliary contacts b of the contactor to point M of the loop. Thus the supply of current to the winding it is terminated and said winding discharges through a closed loop which may be traced from the right hand terminal of said winding through rheostat 22, thence to and v,

through the rectifier loop to the left hand terminal of said winding. Thus the magnetic pull of the winding 13 gradually decreases, the rate of decay of its magnetic flux being variable by the adjustable rheostat 22, and after a lapse of time determined by the adjustment of the rheostat the pull of the winding i3 is overcome by the pull of winding l2, causing the relay 8 to respond to deenergize contactor 6. Contactor 6 thereupon opens to interrupt the welder circuit. The relay 8 will'then remain in circuit interrupting position until the push button switch l is released. If, on the other hand, the push button switch was depressed only momentarily the relay 8 is caused to drop out immediately following opening of contactor it through disengagement of its auxiliary contacts b which are relied upon to maintain the circuit of winding H2 in the event of release of the push button switch l during a welding operation.

Referring to Fig. 2, the same comprises a welder like that'shown in Fig. 1, and a contactor 6, a push button switch l, rectifier elements it, ill, 88 and i9 and an adjustable rheostat 22, all identical with the corresponding elements of Fig. 1. Also this controller comprises a relay 3i differing from the relay ii of Fig. 1 only in respect of its windings and contacts. The armature of this relay normally bridges contacts iii and [It which correspond to contacts ill and ii of Fig. l. and when operated disengages these contacts and bridges a pair of contacts 33 and 3d. The relay has a restraining winding 35 corresponding to the winding l3 pf Fig. l and this winding 35 has the same connections as the winding l3 whereby it functions as hereinbefore set forth in connection with winding l3. Further the relay 3i has an operating winding 36 included in e Wi d? explained in connection with Fig. 1.

circuit between contactor and. transformer winding 1 and said relay is additionally provided with a holding winding iil'connected to points and 3d of a loop containing rectifier elements iii, ll, 32 and d3. This rectifier loop has a connection from point dd through a resistance 45 to line L and a connection from a point 46 through a switch ll? to line L The switch M is of the double throw type having stationary contacts it and it to be engaged selectively, the former to be engaged to complete the rectifier loop circuit just mentioned, and this switch forms part of a selector device having in addition single throw switches 5d and 5!]. The switch 56 is included in a circuit extending from point d6 of the loop by conductors 52 and 53 through said switch by conductor ti l to contact 33 of the relay 3i, while switch 50 is connected between point adjustable rheostat 55 in circuit between point oi the rectifier loop and one terminal of the holding winding 37 of relay 3i.

With the contactor 65 open the welder circuit is interrupted and with the contactor open and 4 the push button switch ll released the relay ti occupies the position illustrated, its restraining winding being supplied by lines L and L through the rectifier loop with unidirectional current as Also the holding winding ill of the relay is under such conditions supplied by lines L L through the second rectifier loop with unidirectional current, and winding 3'l is so designed as to be capable of holding the relay after attraction thereof, but

' incapable of initiating movement of the relay.

Thus inasmuch as energization of the operating winding of relay 3| is dependent upon closure of the welder circuit the system will remain as de scribed pending closure of pushbutton switch 1.

Upon closure of push button switch I circuit 7 is completed as heretofore set forth, from line L through said push button switch. and the normally engaged contacts of relay 3| to and through the operating winding of contactor 6 to line L Contactor 6 thereupon responds and engages its auxiliary contacts 6 to complete a maintaining circuit for itself through the normally closed contacts of relay 3|. Also closure of contactor 6 completes the circuit of the operating winding 36 of the relay, with the result that said relaytends to respond, being temporarily restrained by the magnetic pull of winding 35, which pull is gradually decreased as heretofore explained as the result of short-circuiting the loop containing rectifier elements l6 to it by closure of the push button switch 7] and the aux iliary contacts 6 of contactorli. Thus the response of relay 3i to terminate the welding operation will be as described in connection with Fig. 1, except that it will be subject to influence by the welding current since the-winding 36 is dependent upon. the welding current for energization. As will be understood, by so subjecting the response of the relay to influence by the welding current the welding period will be varied approximately inversely with the welding current. When the relay 3! responds it deenergizes contactor 6 to interrupt the welder circuit and interruption of the welder circuit would cause release of the'relay 3! except for the holding action of winding 31. Winding 31 as heretofore set forth is normally energized by current supplied through the loJp containing rectifier elements 40 to 43, but upon response of relay 3! a circuit is completed from point 46 of the additional of the rectifier loop and the slider of an rectifier loop by conductors 52 and 53, through switch 50 and conductor 54 through the now bridged relay contacts 33 and 34 by conductors B and 51 to point 44 of the rectifier loop. Thus the supply of current to the holding winding 31 is terminated and said winding discharges through the adjustable rheostat 55 which determines the rate of decay of the magnetic flux of said winding whereby after a definite time relay 3| is released. Accordingly assuming that the push button switch 1 has been held depressed throughout the welding operation and remains depressed, return of relay 3| 'to the position shown will cause a repetition of the cycle of operation heretofore described. To terminate welding operations with this controller it is necessary to release the push button switch 1, or to set the selector device for limitation to a single operation.

Assuming shifting of the selector device for engagement of switch 41 with its contact 49, the switches 50 and 5| are opened. As the result of engaging switch 41 with contact 49 supply of current to the holding winding through the rectifier loop is dependent upon closure of push button switch 1 and as a result of opening of switch 50 the aforedescribed short-circuit through the relay contacts 33-34 is interrupted and in consequence the holding winding 31 remains energized until the push button switch 1 is released. Thereupon the winding 31 is deenergized, causing release of relay 3| to enable a further welding operation to be efiected upon reclosure of push button switch 1. As the result of opening of switch 5| the adjusting element of rheostat 55 is disconnected from circuit whereby all of the resistance of said rheostat is included in circuit with the winding 31 to cause it to quickly release relay 3|.

The aforedescribed controller shown in Fig. 2 is set forth and claimed in respect of certain .features thereof in my Patent No. 2,152,608,

granted March 28, 1939, which patent shows preferred circuit connections differing somewhat from those shown in this application.

Referring to Fig. 3, the controller shown therein is identical with that shown in Fig. l with the addition to relay 8 of a winding 60 to overcome the residual magnetism of the restraining winding i3 and the addition of a current transformer 6| in the welder circuit and a loop containing rectifier elements 62, 63, 64 and 65 through which said transformer supplies current to the winding 60. The winding 60 which as compared with winding l3 has only a relatively small number of ampere turns is employed to produce a magnetizing force opposing that of winding i3 whereby the restraining effect of winding I3 is definitely terminated after the latter winding has been short-circuited for a temporary period without need of inclusion of a non-magnetic gap in its magnetic circuit. In other words, the winding 60 prevents sticking due to residual magnetism of winding l3 and with the winding 60 supplied from a current transformer in the welder circuit as shown, its ampere turns will increase with an increase in welding current, thus varying inversely to the value of the welding current the period of effectiveness of winding l3 to restrain the relay 8 against response.

As will be understood, the current transformer 6| may be dispensed with'where its influence is not required, the loop containing the rectifier elements 62 to 65 being then connected across lines L --L or to the secondary winding of a transformer having its primary winding connected across said lines.

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

1. In combination, a source of current, a circuit to be supplied thereby, means to effect closure of said circuit, and a power operated device rendered operative each time said circuit is completed, to effect interruption of said circuit by said first mentioned means, said device having an electromagnetic restraining winding to delay its operation and having under control of said means circuit connections for said winding affording the latter a supply of direct current prior to completion of the circuit by said means and affording said winding a discharge path, said means upon completing said circuit controlled thereby effecting interruption of the supply of current to said restraining winding.

2. In combination, a source of alternating current, a circuit to be supplied thereby, means to effect closure of said circuit, and a power operated device rendered operative each time said circuit is completed by said means, to cause said means to interrupt said circuit, said device having an electromagnetic restraining winding renderlng its operation subject to a predetermined time element and having circuit connections for said winding including a rectifier through which it is connected to said alternating current source at the time said means completes said circuit controlled thereby, said connections for said winding affording the same a discharge path, and said connections being commutatable by said means to interrupt the power supply to said winding while preserving said discharge path.

3. In a controller for an electric circuit, in combination, means to close said circuit and a power operated device rendered operative each time said circuit is closed to effect interruption of said circuit, said device having its operating means subjected to an influence by said circuit and comprising direct current means of the inductive time limit type to delay the aforementioned functioning of said device pending lapse of a given time following closure of said circuit.

4. In combination, a source of alternating current, a circuit to be supplied thereby, an electroresponsive switch to complete said circuit, an electroresponsive relay having normally engaged contacts in the control circuit of said switch, said relay having an electroresponsive winding energized each time said switch is closed and tending under the influence of said winding to move to deenergize said switch and said relay having a restraining winding supplied with rectified current derived from said alternating current source, the circuit connections of said restraining winding being commutatable by said switch and affording a dis-charge path for said restraining winding when the latter is disconnected from said source.

5. In a controller for an electric circuit, in combination, a power operated switch for said circuit, manual control means for said switch and a power operated device for controlling said switch, said manual means being operative to effect operation of said switch to close said circuit but only when said power operated device is in a given position, said device being rendered operative each time said circuit is completed to move from such given position to a position to effect release of said switch to interrupt said circuit and comprising direct currentmeans of the inductive time limit type to delay its move= ment to the latter position pending lapse of a given time following each completion oi said cir= cuit and said device being dependent for return to its first mentioned position upon release of said manual means whereby repeated circuit closing operations require repeated operations of said manual means.

6. In a controller for an electric circuit, in combination, a switch for said circuit, an electroresponsive device, said switch being operable to complete said circuit but only when said device is in a given position, said device having a winding tending upon each completion of said circuit tooperate the same to another position to effect interruption of said circuit, and said device having means to restrain it temporarily against movement to such other position, said restraining means comprising a restraining winding and a discharge loop for said restraining winding rendered effective each time said switch is operated to effect completion of said circuit.

7. In a controller for electric welders, in combination, a power operated switch for the welder circuit, manual control means for said switch, an electroresponsive relay to control said switch, said manual means being operable to effect operation of said switch to complete the welder circuit, but only when said relay is in a given position, said relay having a winding tending upon initiation of each welding operation to operate the same to another position to effect release of said switch to interrupt the welder circuit, and said relay having means to restrain it temporarily against movement to such other position, said restraining means comprising a restraining winding and a discharge loop for said restraining winding rendered effective upon initiation of each welding operation.

8. In a controller for an electric circuit, in combination, an electroresponsive device, means to efiect completion of said circuit but only when said device is in a given position, said device having a winding tending to operate the same to another position each time said circuit is completed and to thereby effect interruption of said circuit, and said device having means to restrain it temporarily against movement to such other position, said restraining means comprising a restraining winding normally supplied from an alternating current source through rectifier elements connected in a loop, said loop being shortcircuited each time said circuit is completed and afl'ording a discharge path for said restraining winding.

9. In a controller for electric welders, in combination, a power operated switch for the welder circuit, manual control means for said switch, an electroresponsive relay to control said switch, said manual'means being operable to efl'ect circuit closing operation of said switch, but only when said relay is in a given position, said relay having a winding tending to operate the same to another position upon initiation of each welding operation and to thereby effect release of said switch, and said relay having means to restrain it temporarily against movement to such other position, said restraining means comprising a restraining winding normally supplied from an alternating current source through rectifier elements connected in a loop, said loop being short-circuited upon initiation of each welding operation and afiording a discharge path for said restraining winding.

'10. In a controller for an electric circuit, in

combination, an electroresponsive device, means for efiecting completion of said circuit but only when said device is in a given position, said device having operating and restraining windings, a loop containing rectifier elements through which said restraining winding is supplied with unidirectional current from an alternating current source and through which extends a discharge path for said restraining winding and a shunt for said loop controlled by said means, said means when completing said circuit also completing said shunt of said rectifier loop to terminate the supply of current to said restraining winding, said device tending upon each circuit closing operation of said means to move to another positionto efiect interruption of said circuit, but being temporarily delayed in so operating by said restraining winding as a function of self-excitation of the latter.

11. Ina controller for electric welders, in combination, an electroresponsive contactor for controlling the welder circuit and control means for said contactor comprising a manual switch, an electroresponsive relay having operating and restraining windings, a loop containing rectifier elements through which said restraining winding is supplied with unidirectional current from an alternating current source and through which extends a discharge path for said restraining winding, and a shunt for said loop controlled by said manual switch, said manual switch being operable to effect circuit closing operation of said contactor, but only when said relay is in a given position, and atthe sametime to complete said shunt of said rectifier loop to terminate the supply of current to said restraining winding, said relay tending upon initiation of each welding operation to move to another position to effect release of said contactor to interrupt the welder circuit but being temporarily delayed in so operating by said restraining winding as a function of self-excitation of the latter.

12. In an electric welder controller, in combination, an electroresponsive contactor and control means for said contactor comprising a manual switch biased to open position, an electroresponsive relay having operating and restraining windings, a closed loop containing rectifier elements through which said restraining winding is supplied with unidirectional current from an alternating current source and through which extends a discharge path for said restraining winding, a shunt for said loop to be completed by said manual switch and to be maintained by contacts of said contactor upon response of the latter, circuit connections rendering said manual switch operable to effect response of said contactor to complete the welder circuit but only when said relay is in a given position, circuit connections causing said relay to tend to move to another position upon initiation of each welding operation, to efiect release of said contactor, and circuit connections rendering unnecessary the retention of said manual switch for completion of the welding operations initiated thereby.

13. In a controller for an electric circuit, in combination, an electroresponsive device, means operative to effect completion of said circuit but only when said device is in a given position, said device having operating and restraining windings, a loop containing rectifier elements and having alternating current supply connections and connections to said restraining winding, a shunt circuit for said rectifier loop to be closed by said means when operated to complete the controlled circuit and a circuit for the operating circuit of said device also to be closed by said means when so operated and to be maintained pending restoration of said means to a given state.

14. In a controller for an electric circuit, in combination, an electroresponsive contactor for said circuit, a manual switch, a relay having an operating winding and a restraining winding, a loop containing rectifier elements, said loop having alternating current supply connections and connections to said restraining winding, an energizing circuit for said contactor extending through the contacts of said relay and through said manual switch, an energizing circuit for the operating winding of said relay extending through said manual switch, a shunt circuit for said rectifier loop extending through said main switch and connections completed by said contactor upon response to maintain all of said circuits independently of said manual switch.

CARROLL STANSBURY.

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