US2016144A - Electrical circuit - Google Patents

Description

Oct. 1, 1935. A. E. HILL 2,016,144

ELECTRICAL CIRCUIT Filed Nov. 2, 1934 INVENTOR @LFEED E H/LL.

ATTORNEY Patented Oct. 1, 1935 UNITED STATES PATENT OFFICE ELECTRICAL CIRCUIT Alfred E. Hill, Detroit, Mich.

Application November 2, 1934, Serial No. 751,196

' 21 Claims.

This invention relates to the art of. opening and closing electric circuits and has to do particularly with a circuit so arranged that when a switch, contact points or the like are brought together or separated to make and break an electric circuit there is no spark or sparking tendency. The object of this is to preserve the contacts; with the present invention the wear on the contacts or switch is substantially that of the mechanical abutment or engagement of the parts against each other with substantially no wear or corrosion due to sparking or sparking tendency.

In some electrical mechanisms circuits are continually opened and closed by a switching device, as for example contact points. Even though the voltage and the amperage of the circuit which are to be opened and closed is designedly held to a minimum, there nevertheless is a small spark; and in order to provide an arrangement which will function perfectly over even a relatively short time, contacts of expensive metals, such as platinum or the like, have to be used, and even then after a considerable period of time the contacts become corroded dueto the sparking, and

an improper function results. The contacts wear out. The present invention aims to provide an electrical circuit wherein contacts are continually brought together and separated, but wherein at the time the contacts are brought together is no electrical current passing across the same; Accordingly, the faces of the contacts are not corroded by electrical spark action and the life of the contact faces is indefinite; in fact, substan-- tially the only wear on the contacts is that caused by the mechanical engagement of the contact faces. This makes it feasible to employ contacts of relatively cheap metal, as no special material or construction need be involved where there is only a mechanical contact at the time the contacts come together or separate. This. arrangement of the circuit or circuits has a wide field of use, and for the purpose of making the disclosure herein one of such uses is shown as that being embodied in a so-called master electric clock.

Fig. 1 is a diagrammatic view showing the circuit arrangement, and showing the coil structure diagrammatically for the purpose of clarity.

Fig. 2 is a diagrammatic view illustrating the circuit arrangement and showing the coil largely in cross-section.

Fig. 3 is a view of diagrammatic nature showing such circuits embodied in an electrical master clock.

Fig. 4 is a view showing the circuits and illustrating a modified arrangement.

Fig. 5 is another view of the circuits and showing a still further modified arrangement. 00 The line which may be supplied with alternat- 0 there is no electric current passing across the same, and when the contacts are separated there;

ing current is illustrated by the wires l and 2, and a coil is generally illustrated at 3. This coil comprises two windings, or in other words two wires which may be simultaneously wound into a coil. A suitable spool is shown at 4 upon which 5 .clear the ends of the wires are shown in an exposed manner, but this, of course, is merely for 15 disclosure purposes, as it will be appreciated that the ends 5 and 6 may be confined in the spool. An iron core 8 may be and preferably is employed with the coil 3 where certain magnetic attraction is desired. The lead wire I connects to the outer 20 end of. one coil, as shown herein the end 5a. A wire or line I!) connects to the outside end 6a and forms part of the circuit. There is a condenser H. and a variable resistance l2 as shownin Fig.

1. From the variable resistance a line l3 extends 25 and this line makes an electrical connection with the lead line 2 and with a contact or switch member.

The contacts, which are illustrative of a suitable switch, where the circuit is to be made and broken 30 are shown at M and I5, and the contact I5 is shown as being a movable one so that it may be brought into and out of engagement with the con -v tact l4. Suitable means may be employed for moving the contact IS on a pivot point [6, and a 35 handle II has been placed on the contact [5 to exemplify the means for moving the contact l5.

A wire I! connects the inner ends of the coils preferably substantially where they join together as at I and runs to the contact M. This wire, 40 together with the contacts, when the same are closed, is termed a shunt herein as it connects the line I with the line 2 short of the condenser II and resistance II. A second condenser I8 is connected across the line I and shunt l1. 5

Before going into the 'modifications shown in Figs. 4 and 5 and the example of an installation embodying the circuit shown in Fig. 3, it is thought that a description of the operation of the circuit shown in Fig. 1 should now be described. 50 When the contacts are open, as shown in Fig. l, the circuit is as follows: 'in one phase of the alternating current the same passes through line I into the coil through the end 5a, through the winding and then into the other winding passing 55 through the ends 5 and 6 and the connection I. The current then passes out through the end 6a through the line Ill to the condenser H, the resistance l2 and line I3 back to the main line 2. At' this time the coil 3 and core 8 exert substantially no no magnetic attraction since the current in the two identically wound wires in the coil are in reverse directions, and the action of the two wind ings in the coil have a balancing action and cancel out any magnetizing effect. At this time the condenser I8 is ineffective as the current takes the path above described through the coil.

The contacts I4 and I5 may now be brought together by suitable means, as for example the means indicated by the handle I1, and since there is no current in the line H there is no current across the contacts when they first come into contact with each other. When contact is made by the contacts I4 and I5 two separate circuits are set up, one of which may be termed a primary and the other of which may be termed a secondary, and the two windings in the coil 3 become respectively primary and secondary windings of a transformer. The primary circuit in one phase is through the line I into the wire end 5a through the end of the wire 5 and the line I1 across the contacts I4 and I5 to the lead wire 2. The secondary circuit comprises the coil with the ends 6 and 6a, line In, the condenser II, the variable resistance I2, line I3, through the contacts I4 and I5, and the line H. Now, the direction of the flow of current in the secondary is just reverse to the direction of the flow of current in the primary in the shunt and at the contacts. It will be noted that current in the primary is in a direction from the contact I4 to the contact I5 and that the direction of the current flow in the secondary is just the reverse from contact I5 to contact I4, with line H constituting a part of each circuit. These opposite currents oppose or cancel out each other at the contacts, with the result that there is no current flow across the contacts, and any time contacts are separated there is no sparking action. At this time, however, there is a strong magnetic action exerted by the electromagnetic device constituted by the coil 3 and core 8 due to the impedance in the coil and the corrected action of the condenser I I. Any suitable device may be operated by or acted upon by the magnetic flux.

When the contacts are closed and the two windings in the coil become in effectprimary and secondary windings of a transformer, the impedance thereof causes the secondary to lag behind. However, the condenser II in the second ,ary tends to create a leading circuit in the secondary. The size or capacity of the condenser is coordinated with the amount of iron in the core, since the amount of iron in the core is a determining factor as regards the lag in the secondary, so that the leading action in the secondary Just balances the lag action due to the impedance,

thus bringing the primary and secondary phases into harmony. Therefore, each winding in the coil 3 exerts a similar magnetizing effect upon the core with the result that there is a strong magnetic action, and this action may be used for any suitable purpose. The magnetic action may be cut by opening the-contacts I4 and I5, at which time there is no sparking because there is no current flow across the contacts and the circuit conditions are restored to their initial con dition with no magnetic attraction. The variable resistance I2 in the secondary is to correctly determine the current in the secondary. The more current the greater the leading action effected by the condenser, and by making a proper adjustment the leading action can be adjusted to a point where the same exactly offsets the lag action. Now, there may be a difference in the two waves in the primary and the secondary, but this difference will be balanced out by the condenser I8 connected in parallel in the circuit of the primary coil. As stated above, however, this condenser is ineffective when the contacts are open and the primary and secondary circuits do not exist as such.

Fig. 4 shows a circuit arrangement the same as that illustrated in Fig. l, but instead of a varia ble resistance in the secondary a variable condenser 2I is shown. This may be used to vary the leading action although it is thought that the use of a condenser of fixed capacity and a variable resistance is preferred because a condenser capable of providing a suitable adjustment would be much larger in dimensions than the fixed condenser and variable resistance. Likewise, as shown in Fig. 4, a variable impedance coil 22 may be used. This creates a lag action in the secondary and supplements the lag action due to the resistance in the transformer when the windings in the coil 3 amount to primary and secondary transformer windings. In this case the total lag action in the secondary would have to be in order to bringthe primary and secondary phases into harmony. These modified forms are shown to illustrate that the idea is to bring the primary and secondary circuits, when the contacts are closed, into harmony.

It is to be appreciated that the variable resistance, as shown in Fig. 2, changes the amperage in the secondary, and that it is within the invention to employ other means to produce this result; for example, a fixed resistance may be used and the core 8 may be made adjustable. By adjusting the core in and out of the coils the amperage is varied. This arrangement is thought to be an expedient one where the device is put in the hands of the public, as for example, in electric clocks, since the core may be adjusted at the factory and this adjustment may be maintained and the correct operation assured. If a variable resistance is used the members of the public may attempt to make some adjustments, with the result that the device will be rendered inoperative or caused to operate imperfectly. Even with this structure the fixed resistance is predetermined and the portion of the circuit having the fixed resistance has means for bringing the primary and secondary phases into exact harmony, with the result that the claims herein calling for such elements cover such, an arrangement.

In Fig. 3 the circuit arrangements are shown as being arranged to operate the pendulumof a master electric clock. Two of such circuits are shown, one on one side of the pendulum and one on the other side, and the reference characters used in Fig. 1 are used on the circuits shown in Fig. 3 and another description thereof is not necessary. So far as the mechanism is concerned a pendulum is shown at 30 equipped with iron armatures 3I and 32 adapted to swing into the opposite coils 3. A cross bar 33 supports oppositelypositioned contacts I4. The contacts I5 may be upstanding and pivotally mountedas at 34. Stop devices 35 and 36 determine the maximum swinging movement of the contact I5. With the parts in position as shown the pendulum is swinging to the left and the contact I4 on the right hand side will strike contact I5, thus setting up a primary and secondary circuit condition, as previously described, in the left hand coil 3. This contact takes place preferably a short distance before the end of the left hand stroke of the pendulum, as for example when the end of the armature 3| is about at the location X, and the coil 3 then magnetically attracts the core 3|. As the pivot contact I5 passes the vertical position will fall away from the right hand contact I 4 and come to rest against the stop 35. The pendulum will now swing to the right, and eventually the left hand contact M will make contact with the contact l5 just prior to the end of the right hand stroke of the pendulum and while the armature 32 is within the right hand coil 3; and at this time the right hand coil 3 exerts a magnetic action upon the armature 32 to draw the same toward the core therein. This action discontinues when the pivoted contact member 15 swings over center and comes to rest upon the stop 36. Thus it willbe observed that the pendulum is kept swinging by the continual setting up and discontinuing magnetic action first in one coil 3 and then in the other. So far as applying the invention to a pendulum is concerned, only one of such circuits need be provided for the purpose of bringing the pendulum up to its full stroke on one side and allowing the same to come to rest naturally and gravitate back without the aid of magnetic action on the opposite side.

In order to bring the pendulum accurately to a stop at the end of each stroke of movement and to prevent the same from striking any part of the cores 8 or the coils 3, an element is provided which will oppose the magnetic action in the coils as soon as the iron of the armatures 3| and 32 approach the limit of their movement. To this end a ring 40 of brass, copper or other non-magnetic metal is placed Within each coil 3 in proximity to the iron cores 8. As soon as one of the armatures enters a brass ring, as illustrated by the dotted line position Y, a magnetic action is set up which opposes the magnetic attraction of the core 8. This opposition increases as the armature enters further into the ring and eventually the forces, the swinging force and magnetic force balance, to determine the end of the stroke of the pendulum. Thus excess power may be applied to the pendulum, as the voltage in the line may vary, but the opposition offered by the use of the ring fixes or limits the degree to which the armature enters the coil.

I claim:

1. An electrical system wherein switching means is to be opened and closed comprising, a circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, a shunt connected into the circuit at a point between the two coils and connected at a second point into the line, switching means in the shunt which, when closed, tends to shunt out of said circuit, the second of said coils and that portion of the circuit between the said second coil and the said second point of connection of the shunt into the line, whereby said first coil becomes in effect a transformer primary in a circuit with the shunt, and the second coil becomes a transformer secondary in a circuit which includes said portion of the first mentionedcircuit and the shunt, with the direction of the secondary current fiow across the switch and in the shunt reverse to the direction of the primary current fiow across the switch and in the shunt, and means in said portion of the first named circuit for bringing the primary and secondary phases into exact harmony so that there is no current flow across the switch.

2. An electrical system wherein switching means is to be opened and closed comprising, a circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, a shunt connected into the cir- 5 cuit at a point between the two coils and connected at asecond point into the line, switching means in the'shunt which, when closed, tends to shunt out of said circuit, the second of said coils and that portion of the circuit between the said 10 second coil and the said second point of connection of the shunt into the line, whereby said first coil becomes in eifect a transformer primary in a circuit with the shunt, and the second coil becomes a transformer secondary in a circuit which 15 includes said portion of the first mentioned circuit and the shunt, with the direction of the secondary current flow across the switch and in the shunt reverse to the direction of the primary current flow across the switch and in the shunt, 20 means in said portion of the first named circuit for bringing the primary and secondary phases into exact harmony so that there is no current fiow across the switch, and a condenser so connected that when the switch is closed the same is 25 in parallel with the said first coil to balance out differences in the waves in the primary and secondary.

3. An electrical system wherein switching means is to be opened and closed comprising, a 30 circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, a shunt connected into the circuit at a point between the two coils and connect- 35 ed at a second point into the line, switching means in the shunt which, when closed, tends to shunt out of said circuit, the second of said coils and that portion of the circuit between the said second coil and the said second point of connec- 40 tion of the shunt into the line, whereby said first coil becomes in effect a transformer primary in a circuit with the shunt, and the second coil becomes a transformer secondary in a circuit which includes said portion of the first mentioned cuit and the shunt, with the direction of the sec ondary current fiow across the switch and in the shunt reverse to the direction of the primary current fiow across the switch and in the shunt, a condenser and variable resistance in said portion'50 of the first named circuit for bringing the primary and secondary phases into exact harmony so that there is no current flow across the switch.

4. An electrical system wherein switching means is to be opened and closed comprising, a 55 circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, a shunt connected into the circuit at a point between the two coils and connected at 60 a second point into the line, switching means in the shunt which, when closed, tends to shunt out of said circuit, and second of said coils and that portion of the circuit between the said second coil and the said second point of connection of 65 the shunt into the line, whereby said first coil becomes in effect a transformer primary in a circuit with the shunt, and the second coil becomes a transformer secondary in a circuit which includes said portion of the first mentioned circuit and the 70 shunt, with the direction of the secondary current fiow across the switch and in the shunt reverse to the direction of the primary current flow across the switch and in the shunt, a condenser and variable resistance in said portion of the first 75 named circuit for bringing the primary and secondary phases into exact harmony so that thereis no current; flow across the switch, and a condenser so connected that when the switch is closed the same is in parallel with the said first coil to balance out differences in the waves in the primary and secondary.

5. An electrical system wherein switching means is to be opened and closed comprising, a circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, a shunt connected into the circuit at a point between the two coils and connected at a second point into the line, switching means in the shunt which, when closed, tends to shunt out of said circuit, the second of said coils and that portion of the circuit between the said second coil and the said second point of connection of the shunt into the line, whereby said first coil becomes in effect a transformer primary in a circuit with the shunt, and the second coil becomes a transformer secondary in a circuit which includes said portion of the first mentioned circuit and the shunt, with the direction of the secondary current flow across the switch and in the shunt reverse to the direction of the primary current flow across the switch and in the shunt, and a variable condenser in the said portion oi? the first named circuit for bringing the primary and secondary phases into exact harmony so that there is no current flow across the switch,

6. An electrical system wherein switching means is to be opened and closed comprising, a circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, a shunt connected into the circuit at a point between the two coils and connected at a second point into the line, switching means in the shunt which, when closed, tends to shunt out of said circuit, the second of said coils and that portion of the circuit between the said second coil and the said second point of connection of the shunt into the line, whereby said first coil becomes in effect a transformer primary in a circuit with the the shunt, and the second coil becomes a transformer secondary in a circuit which includes said portion of the first mentioned circuit and the shunt, with the direction of the secondary current flow across the switch and in the shunt reverse to the direction of the pri'.

mary current flow across the switch and in the shunt, and a variable impedance in the said portion of the secondary for bringing the primary and secondary phases into exact harmony so that there is no current flow across the switch.

7. An electrical system wherein magnetic fiux is to be alternately built up and discontinued by the opening and closing of switching means comprising, a circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, an iron core for the coils, the coil windings being such that their flux building-up actions are opposite, whereby the core is substantially unaffected by magnetic flux, a shunt connected into the circuit at a point between the two coils and connected at a second point into the line, switching means in theshunt which, when closed, tends to shunt out of said circuit, the second of said coils and that portion of the said circuit between the secand coil and the said second point of connection of the shunt into the line,'whereby the first coil tioned circuit and the shunt, with the direction of the secondary current flow across the switch and in the shunt reverse to the direction of the primary current fiow across the switch and in the shunt, and means in said portion of the first named circuit for bringing the primary and sec-- ondary phases into exact harmony so that there is no current flow across the switch.

ii. An electrical system wherein magnetic flux is to be alternately built up and discontinued by the opening and closing of switching means comprising, a circuit for connection to a source oi electromotive force, two similar coils con nected in series in said circuit, herein termed for convenience first and second coils, an iron core for the coils, the coil windings being such 1 nectlon of the shunt into the line, whereby the L first coil becomes in efiect a transformer primary in a circuit with the shunt and the secondary coil becomes a transformer secondary in a circuit which includes said portion of the first mentioned circuit and the shunt, with the direction of the secondary current fiow across the switch and in the shunt reverse to the direction of the primary current flow across the switch and in the shunt, means in said portion of the first named circuit for bringing the primary and secondary phases into exact harmony so that' there is no current flow across the switch, and a condenser so connected that when the switch is closed the same is connected in parallel with the first coil to balance out differences in the waves or the primary and secondary currents.

9. An electrical system wherein magnetic flux is to be alternately built up and discontinued by the opening and closing of switching means comprising, a circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, an iron core for the coils, the coil windings being such that their flux building-up actions are opposite, whereby the core is substantially unaffected by magnetic flux, a shunt connected into the circuit at a point between the two coils and-connected at a second point into the line, switching means in the shunt which, when closed, tends to shunt out of said circuit, the second of said coils and that portion of the said circuit between the second coil and the said second point of connection of the shunt into the line, whereby the first coil becomes in effect a transformer primary in a circuit with the shunt, and the secondary coil becomes a transformer secondary in a circuit which ineludes said portion of the first mentioned circuit and the shunt, with the direction of the secondary current flow across the switch and in the shunt reverse to the direction of the primary current flow across the switch and in the shunt, a condenser and variable resistance in said porton of the first named circuit for bringing the primary and secondary phases into exact harmony so that there'is no current flow across the switch.

10. An electrical system wherein magnetic "flux is to be alternately built up and discon- 5 tinued by the opening and closing of switching means comprising, a circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, an iron core for the coils, the coil windings being such that their flux building-up actions are opposite, whereby the core is substantially unaffected by magnetic flux, a shunt connected into the circuit at a point between the two coils and connected at a second point into the line, switching means in the shunt which, when closed, tends to shunt out of said circuit, the second of said coils and that portion of the saidcircuit between the sec-- and coil and the said second point of connection of the shunt into the line, whereby the first coil becomes in effect a transformer primary in a circuit with the shunt, and the secondary coil becomes a transformer secondary in a circuit which includes said portion of the first men- 25. tioned circuit and the shunt, with the direction of the secondary current flow across the switch and in the shunt reverse to the direction of the primary .current flow across the switch and in the shunt, a condenser and variableresistance 30 in said portion of the first named circuit for bringing the primary and secondary phases into exact harmony so that there is no current flow across the switch, and a condenser so connected that when the switch is closed .the same is in parallel with the first mentioned coil.

11. An electrical system wherein magnetic flux is to be alternately built up and discontinued by the opening and closing of switching means comprising, a circuit for connection to a source of 44; electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, an iron core for the coils, the coil windings being such that their flux building-up actions are opposite, whereby the core is substantially unaffected by magnetic flux,a shunt connected into the circuit at a point between the two coils and connected at a second point into the line, switching means in the shunt which, when closed, tends to shunt out of said 59'- circuit, the second of said coils and that portion of'the said circuit between the second coil and the said second point of connection of the shunt into the line, whereby the first coil becomes in v effect a transformer primary in a circuit with the shunt, and the secondary coil becomes a transformer secondary in a circuit which includes said portion of the first mentioned circuit and the shunt, with the direction of the secondary current flow across the switch and in -the mi: shunt reverse to the direction of the primary current flow across the switch and in the shunt, and a variable condenser in said portion and the firstnamed circuit for bringing the primary and secondary phases into exact harmony so that 5': there is no current flow across the switch.

12. An electrical system wherein magnetic flux is to be alternately built up and discontinued by the opening and closing of switching means comprising, a circuit for connection to a source 70 of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, an iron core for the coils, the coil windings being such that their fiux building-up actions are opposite, 5 whereby the core is substantially unaffected by magnetic flux, a shunt connected into the circuit at a point between the two coils and connected at a second point into the line, switching means in the shunt which, when closed, tends to shunt out of said circuit the second of said coils and ..-5 that portion of the said circuit between the second coil and the said second point of connection of the shunt into the line, whereby the first coil becomes in eifect a transformer primary in a circuit with the shunt, and the secondary coil 10 becomes a, transformer secondary in a circuit which includes said portion of the first mentioned circuit and the shunt, with the direction of the secondary current flow across the switch and in the shunt reverse to the direction of the 15 primary current flow across the switch and in the shunt, and a variable impedance in said portion of the first named circuit for bringing the primary and secondary phases into exact harmony so that there is no current flow across the 20 switch. 13. In an apparatus operated by the alternately building up and discontinuance of magnetic fiux, a. coil for connection to a source of electromotive force, a core for thecoil, means for making and breaking thecircuit foralternately building up and discontinuing magnetic flux, an armature arranged to be attracted by the magnetic flux, and 9, ring of non-magnetic metal adjacent the core into which the armature is adapted to move and in which a magnetic action is set up which opposes the magnetic attraction of the core upon the entrance of the armature into the ring to oppose further movement of the armature.

14. An apparatus operable by electromagnetic force comprising, a pendulum with an armature thereon, an electric circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, a core for the coils, said coils being positioned so as to be effective upon the said armature, a shunt connected into the circuit at a point between the two coils and connected at a second point into the line, switching means in the shunt arranged to be closed by the movements of the pendulum, and. which, when closed, tends to shunt out of said circuit the second of said coils and that portion of the circuit between the second coil and the second point of connection on the shunt into the line, whereby the first coil becomes in effect a transformer primary in a circuit with the shunt, and the secondary coil becomes a trans: former secondary in a circuit which includes said portion of the first mentioned circuit and the shunt, with the direction of the secondary current flow across the switch and in the shunt reverse to the direction of the primary current fiow acros the switch and in the shunt, and 50 whereby magnetic flux is set up by the coils for attraction of the armature, said switch being arranged to open incident to the movement of the pendulum to discontinue the magnetic attraction of the armature, and means in said portion of the first named circuit for bringing the primary and secondary phases into exact harmony so that there is no current flow across the switch.

15. An electrical system comprising, a circuit, a plurality of coils in the circuit the magnetic action of which balance out each other, a shurt across the line, switching means in the shunt which, when closed, tends to cut out certain of the coils from the circuit whereby magnetic 210- tion is set up, and said shunt forms a part of the said circuit, the coils being arranged so that the said certain of the coils have current induced therein when the switch is closed and the shunt being connected so that it is in a circuit with said certain of the coils, with the direction of flow of the induced current in the shunt reverse to the direction of flow in the shunt of the current in the first named circuit, whereby there is no current flow in the shunt and across the switching means as the same is closed and opened.

16. An electrical system wherein switching means is to be opened and closed comprising, a circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, a shunt connected into the circuit at a point between the two coils and connected at a second point into the line, switching means in the shunt which, when closed, tends to shunt out of said circuit, the second of said coils and that portion of the circuit between the said second coil and the said second point of connection of the shunt into the line, whereby said first coil becomes in effect a transformer primary in a circuit with the shunt, and the second coil becomes a transformer secondary in a circuit which includes said portion of the first mentioned circuit and the shunt, with the direction of the secondary current flow across the switch and in the shunt reverse to the direction of the primary current flow across the switch and in the shunt, and means effective when the switch is closed for bringing the primary and secondary phases into exact harmony, so that there is no current flow across the switch.

17. An electrical system wherein switching means is to be opened and closed comprising, a circuit for connection to a source of electro motive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, a shunt connected into the circuit at a point between the two coils and connected at a second point into the line, switching means in the shunt which, when closed, tends to shunt out of said circuit, the second of said coils and that portion of the circuit between the said second coil and the said second point of connection of the shunt into the line, whereby said first coil becomes in effect a transformer primary in a circuit with the shunt, and the second coil becomes a transformer secondary in a circuit which includes said portion of the first mentioned circuit and the shunt, with the direction of the secondary current fiow across the switch and in the shunt reverse to the .direction of the primary current fiow across the switch and in the shunt, means effective when the switch is closed for bringing the primary and secondary phases into exact harmony so that there is no current fiow across the switch, and a condenser so connected that when the switch is closed the same is in parallel with the said first coil to balance out differences in the waves in the primary and secondary.

18. An electrical system wherein switching means is to be opened and closed comprising, a circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit, herein termed for convenience first and second coils, a shunt connected into the circuit at a point between the two coils and said second coil and the said second point of con- 5 nection of the shunt into the line, whereby said first coil becomes in effect a transformer primary in a circuit with the shunt, and the second coil becomes a transformer secondary in a circuit which includes said portion of the first mentioned circuit and the shunt, with the direction of the secondary current fiow across the switch and in the shunt reverse to the direction of the primary current flow across the switch and in the shunt, a condenser and resistance in said por- 15 tion of the first named circuit for bringing the primary and secondary phases into exact harmony so that there is no current flow across the switch, and a condenser so connected that when the switch is closed the same is in parallel with the said first coil to balance out differences in the waves in the primary and secondary.

19. An electrical system comprising, a circuit for connection to a source of electromotive force, two similar coils connected in series in said circuit oppositely wound with respect to the direction of current flow, whereby the coils have a balancing action on each other, and the mag netizing effect therein is substantially cancelled out, said coils being termed for convenience first and second coils, a shunt adapted to be opened and closed and which, when closed, shunts out the second of said coils from said circuit, whereby magnetic fiux is set up by the first coil, and an armature arranged to be attracted thereby.

20. An electrical system comprising, two similar coils arranged in series in a circuit with the windings of the coils oppositely disposed with respect to the direction of current, whereby the magnetic action thereof is substantially balanced 40 out, said coils being termed for convenience first and second coils, a shunt for shunting the second coil out of the circuit, a switch in the shunt, whereby the first and second coils be come, in effect, primary and secondary trans- 5 former coils with like magnetic effects for setting up magnetic flux, means for completing a circuit for the second coil, said shunt and switch being in the circuit for the second coil with the direction of the secondary current flow in the shunt andwacross the switch being opposite to the current fiow of the primary.

21. An electrical system comprising, two similar coils arranged in series in a circuit with the windings of the coils oppositely disposed with respect to the direction of current whereby the magnetic action thereof is substantially balanced out, said coils being termed for convenience first and second coils, a shunt for shunting the second coil out of the circuit, a switch in the shunt, whereby the first and second coils become in effect primary and secondary transformer coils with like magnetic effects for setting up magnetic fiux, means for completing a circuit for the second coil, said shunt and switch being in the 55 circuit for the second coil with the direction of the secondary current flow in the shunt and across the switch being opposite to the current fiow of the primary, and means for bringing the primary and secondary phases into exact harmony so that there is no current flow across the switch.

ALFRED E. HILL.

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