US1765696A - Distribution system for alternating currents - Google Patents

Description

June 24, 1930. G. E. PALMER 1,765,696

DISTRIBUTION SYSTEM FOR ALTERNATING CURRENTS Original FiledAug. 12. 1921 2 Sheets-Sheet l une 24, 1930. G. E. PALMER 1,755,696

DISTRIBUTION SYSTEM FOR ALTERNATING GURRENTS Original Filed Ag. 12. 1921 2 Sheets-Sheet -2 Patented June 24, 1930 -iun 'riazo STATES PATENTl OFFICE GRAiNVILLE E. P ALMER, OF CAMBRIDGE, MASSACHUSETTS, ASSIGNOR, BY MESNE AS- SIGNMENTS, TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMPANY, A COB- IEORATION or PENNSYLVANIA DISTRIBUTION SYSTEM FOR ALTERNATI'NG CURRENTS Application filed August 12, 1921, Serial No. 491,702. Renewed Eebruary 26, 1925.

This invention relates to systems of distribution of alternating currents, being designed for such systems wherein a working circuit or network is supplied with power. from one or a plurality of step-down transformers in independent feeders, feeding in parallel thereto, the number of transformers in operation varying from time to time according to the load conditions of the network. These transformers may be energized from the same or independent sources.

In such systems it is important that the transformers which are disconnected from the feeders shall also be disconnected from the network, not 'only to avoid the core losses due to energization of the transformers from the network, but to insure nopotential conditions across the primary terminals of a transformer otherwise disconnected from potential so that it may be safe to" effect repairs in its feeder circuit. It is evident that if the transformer is mag: netized from the feeder circuit to even a low degree the primary side of the transformer It is also important that the energy of. any-transformer which it is desired to cutinto the network shall be substantially in phase therewith and that its potential shall be sufficiently higher than that of the portion of the network to which it is connected so that'it will'feed load thereto as soon as it is cut in. r

men, this invention provides means for automat-ically opening the secondary side of the transformer on any reverse energy flow thereto from the network. This acts to disconnect the transformer from the network as soon as its feeder circuit is opened, a short circuit occurs therein, or whenever, for any reason, its potential drops below work. This means is also designed to close the secondary circuit to the network automatically only when the primary circuit is closed, whenthe current of the secondary is substantially in phase with the network, and when it has a sufficiently higher potential to feed energy thereto.

By the actuation of a single switch in the feeder circuit on the primary side of the transformer it is therefore possible with this invention to completely disconnect the transformer from the network and to connect it only when conditions are favorable for it to take load and feed energy to the system, this connection continuing only so long as such favorable conditions persist. Any failure of such conditions results in immediate disconnection of the transformer from the network out of control of the main switch.

The present invention is an improvement over that shown in my Patent No. 1,597,865, issued Aug. 31, 1926, on an application which was copending with the present ap plication. 7 u

The present invention differs materially in several respects from that shown in my prior atent. For example, in the present inventlon the phase position, or the phaseangle characteristics of the voltage across the interruption points of the circuit interrupter, disposed in the secondary circuit of the distribution transformer, is employed to control the automatic closure of the interrupter. In the patent referred to, the system is independent of phase-angle considerations.

Further, in the present invention,'the circuit interrupter controlling the secondary circuit of the transformer is provided wit closing means which operate only when the that necessary to feed energy to the neti vention over my prior patent.

For a more complete understanding of this invention together with further objects and advantageous details and combinations of parts, reference may be had to the accompanying drawin s in which- Figure 1 is a dlagram o the system showing two transformers for supplying energy to the working circuitipn network, one of the transformers being' -iconnected thereto and the other disconnected therefrom.

Figure 2 is a front view of the automatic switch in the transformer secondary.

Figure 3 is a section on line 33 of Figure 2 partly broken away,

Figure 4 is a fragmentary view similar to Figure 3, but with parts in different psitions.

Referring to Figure 1 at A is indicated a suplply transformer for supplyin energy to hig tension mains B. A plura ity of step down transformers having primary and secondary windings and 7 are shown connected to the high tension main B, although if desired separate sources of power mig t be used instead of the common high tension main.

'At 14 are shown the usual circuit .breakers in the primary-sides of the transformers these circuit breakers being, if desired, 0 the usual no-voltage overload t overload coils being indicated at 15. ese circmt breakers are ordinarily located in power substations and may be closed by hand in the usual manner when it is desired to cut in a ste down transformer to the load circuit. e step-down transformers are located near the load circuit in order to secure the advantages of high-tension distribution.

At 3, 5, and 6 are shown portions of the load network herein shown of the usual three wire system having outside wires 5 and 6 and a grounded neutral 3. This network may, however, be of any usual type. The secondar 7 of the transformer is also grounde at its central point in the .usual manner.

Interposed between the secondary 7 of the transformer and the network 5 and 6 is an automatically acting switch shown in detail in Figures 24. This switch com rises two pairs of stationary main termina contacts 112 and 113, a pair of switch arms 17 being employed to make or break contact with the line terminals 113, while being connected permanently with the load terminals 112.

The switch arms 17 are carried by an insulating bar 18 which is fixed to an arm 20. This arm is pivoted at 19 and pivoted thereto at 26 is a solenoid core which may be drawn into a solenoid 24 on energization thereof. lVhen the core is so drawn in, the arms 17 are brought into contact with the terminals 113 to close the switch. In order that the switch may remain closed without continuous energization of the solenoid 24, a latch mechanism has been provided. This mechanism comprises a spring pressed latch bolt 52 carried at the upper end of the arm 20 which cooperates with a pivotal latch plate 54 having a portion 47 engageable by the bolt. The switch arms are normally held in open position by means of a sprin 22 so that the solenoid 24 being de-energize on release of the latch mechanism the switch immediately opens.

In order to de-energize the solenoid 24 as soon as it has effected the closing of the switch, a supplemental switch comprising a movable contact arm 33, adapted to make contact between a air of terminals 34, has been provided. T is arm 33 is carried b a lever 35 also pivoted on the pivot 19. sprin 39 normally urges the lever 35 downward y to bring t e contactor 33 out of engagement with the contacts 34, but when the arm 20 is in the position shown in Figure 3 with the main switch open, an abutment screwv 41 engaging on the under side ofthis lever holds the contactor 33 in closed 1- tion. When in this position it is hel l iy a latch finger 42 enga 'ng the rear end of the lever 35, and hel in this position by means of the lower end of the arm 20 engaging a spring arm 45 fixed to thelatch. As the arm 20 approaches its vertical position where it may be engaged by the atch 47, the lower end of the arm 20 enga an abutment screw 59 on the latch 42 anfi ocks this latch .out of engagement with the lever 35, whereupon the spring 39 throws the contactor 33 out of engagement with the contacts 34 and breaks the circuit through the coil 24.

A pair of coils 27 is employed to control the passage of current through the coil 24 when its circuit is otherwise closed, each.

of these coils being provided with opposed yoke shaped armature members 28 and 29, which when these coils are energized, come together by the raising of the armature 28, completing the magnetic. circuit through both armature members. The armature 28 may impinge at its lower end on the inner end of the atch 54 so as to raise the outer end thereof in case the coils 27 become de-- energized. This action releases the latch III mechanism and allows the switch arms 17 to open. In this position of the armature 28 considerable current is required in the coils 27 to raise it therein, but when it is raised a much less current is required to hold it in this position. This action is important in connection with its controlling mechanism to stabilize the system as will be later described.

A switch in series with coil 24 and controlled by the magnets 27 comprises a pair of fixed contacts 32 between which may be moved into bridging contact a contacting arm 31 carried by a pivoted arm 56. The inner face of this arm 56 is formed cam shaped and is engaged by the cross bar of the armature 28 when this armature is drawn upwardly so that the arm 56 is swung outwardly and the contacting piece 31 made to bridge the contacts 32, thus completing the circuit through the solenoid 24 when the contacts 34 are also the member 33.

The lower end of the arm 56 carries a rearwardly extending finger 60 which is struck by the cross bar of the armature 28 in falling just before it strikes the latch bar 54 so as to rock the arm 56 rearwardly and break the connection between the terminals 32 just prior to releasing the main-switch lat-ch.

From this description it may be seen that when the switch arms 17 are open the switch contacts 34 are connected, it only remaining to connect the contacts 32 by energizing the coils 27 to energize thesolenoid 24 so as to close the switch arms 17, and that when these switch arms are closed the contacts 34 are disconnected so that no current flows through the solenoid 24, the arms 17 being held closed by the latch mechanism which is maintained in operation only so long as the armature 28 is in raised position through energization of the coils 27. It is also evident that as soon as the armature 28 is allowed to fall the contacts 32 are first disconnected to break the circuit through the solenoid 24 at this point, and the latch mechanism is then tripped to permit opening of the switch arms 17 before the contacts 34' are bridged.

This mechanism is thus an electromagnetclosed, no-voltage opened switch.

For the purpose of controlling the current in the coils 27 a watt relay has been provided, this relay comprising a nonmagnetic disk 205 fixed to a shaft 202, this shaft being supported for rotation. This relay is provided with a potential coil 203 which is connected across the network 5 and 6, the windings of the reactances 207, 207 being interposed therebetween. This potential coil is of the usual construction, being of large inductance so that the current therein lags behind the normal voltage in the netbridged by.

the left reactance coil 207, these reactance coils connecting the terminals 112 to the network 5 and 6, the two windings preferably having a common magnetic circuit but insulated therefrom.

From this construction it will be seen that when the main switch arms 17 are closed, current will flow through the coils 204 since the secondary 7 of the transformer is now connected through the coils 207 to the network.

The coils 208 are connected across terminals 112 and 113, the right hand coil 208 being connected across the right hand terminals, and the left hand coil being connectedacross the left hand terminals. As this connection shunts the main switch arms 17 when these arms are open, resistances 209 and 210 are inserted in series with the coils 208 in order to reduce the current flow to a very small amount so that when the switches 17 are open and the circuit breaker 14 is out, insuflicient current will flow through the secondary 7 from the network to magnetize the transformer core and cause potential to exist across the primary terminals of the transformer. Resistances are employed for this purpose, so that the currents through these coils may be substantially in phase with their potentials.

The shaft 202 carries a cam member 'of insulating material 219, which when the disk 205 is turned in a clock-wise direction, until a pin 100 thereon contacts a fixed stop 101, impinges against a spring contact 211, breaking contact with the arm 212 and establishing contact with an arm 206. The spring arm 211 engaging on the cam member 219 exerts a small counterclockwise turning effort on the disk 205, tending to retain the contact between the members 211 and 212, a pin 102 fixed to the disk, then contacting with the stop 101.

It will be noted that the left hand terminal of the coils 27 connects at a to the left hand terminal 113 and the right hand terminal of the coils 27 connects through the resistance 215 to the right hand terminal 113 at 'b, and that from a point between the coil 27 and resistance 215 a connection is made to the spring relay contact 211. The spring relay contact 206 connects to a and spring relay contact 212 connects to b so that when the relay has revolved counterclockwise and is in position shown at the left in Figure 1 the resistance 215 is by-passed and the full potential of this circuit is impressed on the coil 27, while when the relay has re volved clockwise to the position shown in v the right hand portion of Figure 1, the coils 27 are by-passed and the resistance 215 absorbs the potential impressed on the circuit. In the intermediate position of the contact 211 where it is out of contact with both members 206 and 212 the coils 27 and the resistance 215 are in series. \Vhen the resistance 215 is by-passed, as in the left hand portion of Figure 1, the current flowing through the coils 27 under normal conditions is sufficiently large to raise the armature 28 from its lowered position and close the main switch arms 17 in the manner above described. \Vhen the coils 27 are short-circuited, as shown at the right hand portion of Figure 1, the armature 28 is caused to fall, thus opening the main switch arms 17 When both the coils '27 and the resistance 215 are in series suflicient current passes through the coils 27 to hold the armature 28 in raised position in case it is in that position at the time, but this current is insufficient to raise this armature in case it is in lowered position. \Vhen the contact 211 is therefore out of contact with both the elements 206 and 212 the main-switch is not actuated but remains in either position in which it was prior to the separation of the contact 211 from either contact 206 or 212.

As before stated the coil 203 derives its potential from the network 5 and 6 while the coils 204 and 208 are energized in accordance with the current in the secondary feeder circuit. If therefore the direction of energy flow in this secondary circuit changes, the direction of torque on the disk 205 also changes. Assuming that the switch arms 17 are closed, current produced by energy flow from the transformer to the network results in a flux, that with the flux produced by the current,in coil 203 causes a counterclockwise rotation of the disk 205 to its limit of'motion and allows the contact 211 to complete the circuit through the contact 212. The switch arms 17 are maintained closed as above described and the feeder circuit is connected to the network to feed current thereto.

In case the energy flow is in the reverse direction, the flux produced by current in the coils 204 is such as to cause clockwise rotation of the disk 205 to its limit of motion in that direction thus moving the contact 211 away from the contact 212 and finally contacting with member 206, whereu on the switch arms 17 are opened by the e-energization ofv the coils 27 and the feeder is isconnected from the network. This action breaks the energy flow through the coils 207, thus discontinuing the current through the coils 204, but establishes a path from the network to each of the coils 208 and their resista'nces 209 and 210 to the terminals 113, 113 at a and 6, this path being completed throu h the secondary winding 7 of the transfbrmer. As energy now flows from the network to the transformer, assuming that the primary of the transformer is deenergized, a flux is roduced in the coils 208 that with the fiuxin the coil 203 results in work (which also supplies potential to'the.

coil 203) operate to maintain-the disk revolved in a clockwise direction to its stop, thus maintaining the switch arms 17 open. If the potential to the feeder and primer of the transformer is restored in phase wit the potential of the network, the potential impressed upon the coils 208, 208 is the difference between that of the network and feeder and as this difference of potential appgoaches zero the clockwise torque on the dis 205 is reduced so that the contact member' 211, which as above described is of sprin material tends to rotate the disk throng pressure on the member. 219 in a counterclockwise direction to establish electrical connection between the contact members 211 and 212. It is not desirable, however, that such action should take place when the difference of potential between the feeder and network becomes zero, since this would result in an unstable condition wherein slight changes of tential in either the feeder or the networ tending to rotate the disk in one or the'other would result in flux direction which might result in the main I switch opening and closing rapidly as long as this unstable condition persisted. It is therefore desirable that the feeder remain disconnected from the network until the potential therein is somewhat above that of the portion of the network to which it will be connected.

-To provide for this action a resistance 0 is shunted about the right hand coil 204 of the relay. It .is well known that if otential is impressed on the otential coi only of a watt relay of this escription havin a co-operating short-circuited winding, su

ficient flux is produced in-the short-circuited winding to impart rotation to the relay disk, this action being common] made use of in watt meters to overcome t e friction of the iao disk bearings. In order that this torque may be regulated in amount a so-called shading. coil, is used by which the flux in the two current coils may be thrown somewhat out by the coils 204 by potential impressed on the coil 203. This resistance e is made adjustable so that with the coil 203 alone enerr in.

memes gized, enough unbalanced flux is produced in these coils 204 to cause a clockwise rotation of the disk so that a zero difference of potential occuring across the open switch terminals, the coils 208 thereby being idle, does not result in a counterclockwise rotation of the disk 205 to close the contacts 211 and 212. These contacts therefore do not close until the potential at the terminals 113 is sufficiently higher than at the terminals 112 so that when the switch arms 17 are closed energy will flow to the network the coils 204 then being energized, due to their shunt connection about the reactance coils 207, and maintaining the disk rotated counterclockwise and thereby allowing the elements 211 and 212 to remain in contact. By this means the switch is closed and held closed in a stable condition when the proper phase relations obtain in the feeder and load circuits. Should conditions in the circuit change sufficiently to impart a clockwise rotation to the disk 205 to break connection between the elements 211 and 212, the switch arms 17 will still remain closed until the contact is made with the element 206, since in this condition the coils 27 and the resistance 215 are in series and, as above stated, cur rent of suflicient strength then passes through the coils 27 to retain the armature 28 in raised position. When contact is made with the element 206, however, the coils 27 are by-passed and the armature falls causing the main switch 17 to open as before described. On the other hand, should the main switch open, it will not be closed until the arm 211 contacts with the terminal 212, since before such contact, even though coils 27 and the resistance 215 are in series, insufficient current passes through the coils 27 to raise the armature 28.

It will be seen from this description that it is possible to cut out the various feeder circuits from the load network as desired by switches located in the primaries of the transformers in the feeder circuits and that when this is effected the transformer secondary is immediately disconnected from the network and insufficient current is allowed to pass from the network to the secondary of the transformer to magnetize its core so as to produce potential across the primary terminals. It is also apparent that whenever the main switch or circuit breaker on the primary of the transformer is closed the secondary will not be connected to the network unless the potential of the feeder is sufficiently above that of the network to feed energy thereto and is substantially in phase therewith, and that any cause which results in a lowering of the feeder potential to a value such as would permit reverse flow of energy from the network, or a material difference in phase, will immediately result readily determine the load supplied by each.

feeder, it is apparent 'that he may reduce the transformer core loss of the system "to a minimum by maintaining connections only to the number of feeders necessary to supply the load actually connected to the system, thus permitting the operation of all the fragsformers connected at substantially full When it is desired to cut in additional transformers to meet the load requirements of the network, the potential of the feeder should be raised to a point somewhat above the potential of the load circuit where the connection is to be made, and the main circuit breaker or switch thrown in. If the conditions are then proper for ener to flow to the network, the secondary o the feeder transformer Will then automatically be cut in.

Having thus described an embodiment of this invention it should be evident to those skilled in the art that many changes and modifications might be made without departing from its spirit or scope as defined by the appended claims.'

I claim:

1. In an alternating current system of distribution, a working circuit, a plurality of feeder circuits arranged in multiple for feeding energy to said working circuit, a transformer in each feeder circuit, a switch in the primary circuit of each transformer, and means in the secondary circuit of each transformer acting to close and maintain closed said secondary circuit when the working circuit is energized when said switch is closed, the potentials of said secondary and said working circuit are a proximately in phase, and the potential of said secondar circuit is sufiiciently higher than that of said working circuit to insure energy flow to said working circuit on the closing of said secondary circuit.

2. In an alternating current system of distribution, a working circuit, a transformer, a feeder circuit connected to said working circuit through said transformer, a switch in the secondary circuit of said transformer, means including a relay for controlling said switch, said relay having potential and current coils, one of said coils energized across said working circuit and another in accordance with the current flowing in said working circuit, said coils being so disposed as to actuate said relay reversely with opposite directions of energy flow between said feeder and working circuitto open said switch when said energv flow is from said working circuit to said feeder circuit, and a shading coil in said relay acting to prevent the closing of said switch until a predetermined potential difference exists between said circuits.

3. In an alternating current system of distribution, a working circuit, a transformer, a feeder circuit for feeding energy through said transformer to said working circuit, a switch in the secondary circuit between said transformer and working circuit, means including a resistance and a relay electrically closed for controlling said switch, said relay having a potential coil in shunt with said workin circuit and carrying a current substantiafiy out of phase with the potential of said working circuit, and a plurality of current coils, certain of said coils being connected with a portion of said secondary circuit to derive current substantially in phase therewith when said switch is closed, and certain of said coils being in series with said resistance and shunted across the switch terminals to carry current corresponding to the relative potentials of said secondary circuit and working circuit when said switch is open, said potential and current coils being so related as to actuate said relay means dependent upon the direction of flow of energy between said working and feeding circuits so as to close said switch when the flow is to said working circuit and to open said switch when the flow is to said feeder circuit. a

4. In an alternating current system of distribution, a working circuit, a transformer, a feeder circuit for feeding energy through said transformer to said working circuit, a switch in the secondary circuit between said transformer and working circuit, means including a resistance and a relay for controlling said switch, said relay having a potential coil in shunt with said working circuit, and a plurality of current coils, certain of said coils being connected with a portion of said secondary circuit to derive current substantially in phase therewith when said switch is closed, and certain of said coils being in series with said resistance and shunted across the switch terminals to carry current corresponding to the relative potentials of said secondary circuit and working circuit when said switch is open, said potential and current coils being so related as to actuate said relay on flow of energy between said working and feeding circuits so as to close said switch under predetermined conditions and to open said switch when the flow is to said feeder circuit, and a resistance shunted about one of the current coils of said relay to unbalance the flux therein and prevent the closing of said switch until the potential of said transformer secondary is somewhat higher than that of the load circuit where it is connected.

5. In an alternating current system of distribution, a working circuit, a plurality of feeder circuits arranged in multiple for feeding energy to said working circuit, a switch having line and load terminals in each feeder. circuit, and' mechanism subjected to the phase position of the potential across the line and load terminals of each' switch acting to close said switch only when the potention of said line terminal is higher than that of said load terminal.

6. In an alternating current system of distribution, a working circuit, a plurality of feeder circuits arranged in multiple for feeding energ to said working circuit, a switch having 'ne and load terminals in each feeder circuit, and mechanism subjected to the phase position of the otential across the line and load terminals 0 each switch actin to close said switch only when the potentia of said line terminal is higher than that of said load terminal, andyresponsive to direcnected across the switch and a third one of said coils being so connected to the working circuit as to be energized in accordance with a function of the current traversing said working circuit. v

8. In an alternating-current system of distribution, a working circuit, a plurality of feeder circuits arran ed in multiple for feeding energy to sai working circuit, an automatic switch in each feeder circuit, a

relay means connected to each feeder circuit for controlling the closure of the associated switch including means for biasin said relay to prevent closure of said switc when the potention of said feeder is equal to or lower than the potential of said working circuit.

9. In an alternating-current system of distribution, a working circuit, a plurality of feeder circuits arran ed in multiple for feeding energy to sai working circuit, an automatic switch in each feeder circuit, a rel y means including a plurality of cooperating coils for controlling the opening and the reclosure of each switch, said coils being so arranged that the relay means operates in accordance with the direction of the flow of energy in the feeder circuit when the switch is clbsed and upon the occurrence of a predetermined phase position and difieracross the working working circuit. '5

11. In an alternating-current system of distribution, aworking circuit, a feeder circuit for feeding energy thereto, a switch in the feeder circuit and a relay controlling said switch according to predetermined circuit conditions, said relay including a potential coil connected across said working circuit, a divided current coil energized in accordance with the currents in separate conductors of the working circuit and another divided coil connected across the break contacts of the switch.

12. In an alternating-current system of distribution, a working circuit, a feeder circuit for feeding energy thereto, a switch in the feeder circuit and a relay controlling said switch according to predetermined circuit conditions, said relay having apotential coil connected across said working circuit, a current coil energized in accordance with the current traversing the working circuit when the. switch is closed, another coil connected across the break contacts of the switch and a variable resistor associated with said current coil and operative to control the current therein to render the relay unresponsive when the switch is open until a predetermined difference of potential exists across the break contacts of the switch.

13. In an alternating-current system of distribution, a working circuit, a transformer, a main switch, a feeder circuit connected to said working circuit through said transformer and said switch, and means ineluding a relay for controlling said switch according to whether the transformer is supplying energy to the working circuit or the working circuit to the transformer, said relay comprising a movable inductiondisk armature and a contactive device controlled thereby to control the main switch, magnetizable element for establishing one magnetic flux field according to the voltage cf the working circuit, means for establishing a second magnetic flux field to cooperate with the first field to-actuate the disc armature, and means for independently energizing said second flux-establishing means according to the current transferred between the transformer and the workin circuit when the main switch is closed an according to the phase position of the potential difference across the break terminals of the main switch when it is opened.

14. In an alternating-current system of distribution, a working circuit, a transfor mer, a main switch, a feeder circuit con-- nected to said working circuit through said relay comprising a movable induction disk armature and a contactive device controlled thereby to control the main switch, a magnetizable element for establishing a magnetic flux field responsive to the voltage of the workin circuit, and a second element for establis ing a cooperating flux field to control the disc armature, current-transformer means for energizing the second element in accordance with the current transferred between the transformer and the working circuit when the main switch is closed, and means independent of the current-transformer means for energizing the second flux-establishing element in accordance with the phase position of the trans former and the working circuit potentials when the main switch is open.

15. An alternating-current system of distribution including a network or load circuit fed by a plurality of secondary'supply circuits, a high-tension feeder circuit, a switch in the feeder circuit, a transformer bank between the feeder circuit and each supply circuit, reactance means in each supply circuit, a network switch in each supply circuit, and network-switch-control means positively actuated in accordance with the transformer secondary and network voltages for automatically closing the network switch only when the feeder switch is closed and when the secondary voltage of the transformer hank exceeds in value the network voltage and is approximately in phase therewith, and means connected to the reactance means and responsive to reverse-current. enorgy in a direction from the network to the feeder for opening the network switch.

16. The combination with a low-voltage network fed by a plurality of low-voltage supply circuits, of reactance means in each supply circuit, a network switch in each supply circuit, and network-switch-control means including means positively actuated in accordance with the supply circuit and network voltages for automatically closing the network switch when the voltage on the supply side of the network switch is greater in magnitude than, and is approximately in I phase with, the voltage on the network side of the network switch, and means connected to the reactance means and responsive to reverse-current energy in a direction from the network to the supply source for opening the network switch.

17. The combination with a low-voltage secondary network fed by a plurality of low-voltage supply circuits, of a network switch in each supply circuit, and networkswitch-control means including means positively actuated in accordance with the supply circuit' and network voltages for automatically closing the network switch independently of network-load conditions when the voltage -on the supply side of the network switch is greater in magnitude than, and is approximately in phase with, the voltage on the network side of the network switch.

18. The combination with a circuit-interrupter in an alternating-current electric circult, of interrupter-closing means including relay-closing means having positive electrical-closing-torque characteristics associated with said circuit for positive response in accordance with a plurality of electrical quantities of said circuit, one quantity being derived from across the interrupter break contacts on opposite sides of the interrupter and in the same phase conductor of the electric circuit, and another uantity being derived from the circuit conductors on one side of the interrupterj 19. In an alternating-current system of distribution including a network load energized by a plurality of parallel electric circuits, the combination with a circuit-interrupter in each of said circuits, of interrupter-control means including relay-closing means having positive electrical-closingtorque characteristics associated with said circuit, said relay being responsive positively to a plurality of electrical quantities, one derived from across the interrupter break contacts or interruption points on opposite sides of the interrupter and in the same phase conductor of the electric circuit, and another derived from the circuit conductors on one side of the interrupter, and including relay-opening means responsive to reverse energy in the circuit.

20. In an alternating-current system of distribution, a working circuit, a plurality of secondary circuits connected in parallelcircuit relation for supplying energy to the working circuit, a transformer connected to each secondary circuit, a circuit-interrupter in the primary feeder circuit to each transformer, and means in the secondary circuit of each transformer acting automatically when said'secondary circuit is open to close said secondary circuit only when the switch in its primary circuit is closed and the voltage of the secondary circuit is greater than the voltage of the working circuit, and acting automatically when said secondary is closed to open said secondary circuit when conditions are such as to permit energy flow from the working circuit to the secondary circuit.

21. In an alternating-current system of distribution, a working circuit, a plurality of supply circuits in parallel-circuit relation for feeding or supplying energy to said working circuit, a switch in each supply circuit, and mechanism subjected to voltage across the terminals in the same phase conductor on opposite sides of each switch acting automatically when said switch is open to close said switch only when the value of the terminal voltage on the supply side of the switch is greater than that on the work side of the switch and IGSPOIlSlX'G to direction of energy flow from the working circuit toward the supply circuit for opening said switch.

22. In an alternating-current system of distribution, a working circuit, a plurality of supply circuits for feeding energy to said working circuit, a transformer bank connected to each circuit, a switch in each circuit, and mechanism subjected to voltage across the terminals in the same phase conductor on opposite sides of each switch acting automatically when said switch is open to close said switch only when the value of the terminal voltage on the supply side of the switch is greater than that on the work side of switch and responsive to direction of energy fiow from the working circuit toward the supply circuit for opening said switch.

23. The combination with a transformer having a high-voltage primary circuit and a low-voltage secondary circuit connected thereto and connected to a load, of a switch in each of said circuits, means for operating both of said switches upon the occurrence of a fault therebetween or upon opening the primary switch, and means whereby the secondary switch is automatically reclosed only when the primary switch is closed and dependent only upon a voltage ener ization of the transformer side of the secon ary switch to a value greater than the voltage on the load side of the secondary switch when the voltages have a predetermined phase position.

24. In an alternating-current system of distribution, means for supplying alternating current, a working circuit, a switch between the supply means and the working circuit and means acting to close the switch dependent upon the magnitude and relative phase position of the voltages on both sides of the break contacts of said switch and to maintain said switch closed independent of load or fault conditions on the working circuit 25. The combination with a low-voltage alternating-current network and a plurality of supply circuits therefor, of distribution transformer banks connected to the supply circuits, and means in each transformer secondary circuit' including relay apparatus subjected to positive electrical closing torque characteristics acting electro-responsively to connect its associated distribution transformer bank to the low-voltage network when the transformers are capable of supplying load and to disconnect the transformer from the network when the flow of energy is reversed or from the network tothe transformer.

26. The combination with a low-voltage alternating-current network and a plurality of supply circuits therefor, of distribution transformers connected to supply energy to the network through the supply circuits, a switch in each supply circuit, and means including relay apparatus subjected to positive electrical closing torque characteristics acting automatically to close the switch when the incoming transformer voltage is of such value and direction as to cause the transformer to supply energy to the network and to open the switch when the flow of energy is reversed.

27. The combination with a low-voltage network and a plurality of independent supply circuits therefor, of distribution transformers connected to the network, a switch in each supply circuit between the transformer and the network, and means including relay apparatus having positive electroresponsive torques for automatically closing or opening the switch according to whether the transformer is in condition to supply energy to the network or whether the network is supplying energy in a direction from the network to the transformer.

28. An alternating-current system of distribution including a working circuit, a plurality of feeder circuits connected in multiple for feeding energy to said working circuit, an automatic switch in each feeder circuit, switcl1-control means connected to each feeder circuit for controlling the closure of the associated switch including means for preventing the closure of said switch when the voltage of said feeder is equal to, or lower than, the voltage of said working circuit.

29. The combination with a plurality of parallel-connected transformers connected to a network, of means associated with each transformer circuit responsive to the direction of the potential difference between the transformer and the network for controlling the connection of the transformer to the network only when the transformer voltage is greater than the network voltage and to the reverse direction of energy transferred from the network to the transformer for controlling the disconnection of the transformer from the network. ,4

30. In a system of distribution for alternating current, the combination with a source of energy, a network and a transformer for translating energy therebetween, of a switch between the transformer and the network, and means for automatically closing the switch only when the primary circuit 31. In a system of distribution for al-' ternat-ing currents, the combination with a source of energy, a network and. a trans former for translating energy therebetween, of a switch between the transformer and the network and means for controlling the operation thereof including means responsive to the direct-ion of energy flow between the transformer and the network while the switch is closed and responsive only when the direction of potential difference is from the transformer to the network when the switch is open.

32. The combination with a high-tension circuit having a switch therein, a low-tension circuit and a transformer therebetween, of a switch between the transformer and the low-tension circuit, and means for closing the lastnamed switch only when the transformer secondary voltage is greater than that of the low-tension circuit and for opening the switch when the low-tension circuit is in energy-delivering condition relative to the transformer. 33. The combination with a plurality of parallel-connected transformers having secondary windings connected to a common network load circuit, of a switch between each of the transformers and the network and switch-control means including means for preventing the switch from closing until the transformer secondary voltage is higher than, and approximately in phase with, the network voltage, and means responsive to energy flow in a direction from the network to the transformer for opening the switch.

34. In an alternating-current system of distribution including a plurality of parallel electric circuits connected to a network load, the combination with a transformer and a circuit breaker connected thereto in each circuit, of breaker-control means including closing means responsive only when the relative phase position of the voltages on both sides of the open breaker-interruption points are substantially in phase and the transformer voltage is higher than the network load voltage, and opening means responsive to the direction of energy flow through the closed breaker towards the transformer.

35. The combination with a plurality of parallel-connected transformers connected to a common network load, of a switch between each transformer and the network, and

switch-control means including closing .cluding closing means dependent upon the closed position of the primary switch and upon the phase position of the resultant of the transformer secondary and network voltages, and including opening means energized from the reactance means and dependent upon energy flow in a direction from the network to the transformer.

37. The combination with a circuit, of a circuit-interrupter therein and interruptercontrol means including means for closing the interrupter dependent upon a predetermined hase position of the voltages on both sides 0? the break contacts of the interrupter when it is open and for opening the interrupter dependent upon the direction of the energy flowing through it when it is closed.

38. The combination with a transformer for energizing a load, of a circuit-interrupter therebetween and interrupter-control means including means for closing the interrupter dependent upon a predetermined phase position of the voltages on both sides of the break contacts of the interrupter when it is open and for opening the inter- 'ing closin rupter dependent upon the direction of the energy flowing through it when it is closed.

39. The combination with a plurality of transformers for energizing the same load, of a circuit-interr'u ter between each transformer and the loa and interrupter-control means including means for closing the interrupter dependent upon a predetermined phase position of the voltages on both sides of the break contacts of the interrupter when it is open and for opening the interrupter dependent upon the direction of the energy flowing through. it when it is closed.

40. The combination with a circuit interrupter, of interrupter-control means includmeans responsive to thephase position 0 the voltage across the break contacts of the interrupter and opening means responsive to the magnitude and phase position of the current through the closed interrupter, said control means including a relay electrically closed and having a voltage winding connected to be energized from one side only of the interrupter, a second winding com rising sections connected to be energized rom separate phase conductors of the circuit, and a third winding connected across the interrupter break contacts, and said relay also having a shading coil for biasing the relay contacts toward interrupter-opening position so that the interrupter will close only in response to a value of voltage higher on the supply side of the interrupter than that on the load side.

41. In an alternating-current system of distribution, a working circuit, a feeder circuit for supplyin energy to said working circuit, a switch or controlling the energy flow in said feeder circuit, and a relay means connected to said feeder and working circuit for actuating said switch and responsive to direction of energy flow therethrough between said feeder and working circuit to effect the opening of said switch on flow of energy from said working circuit to said feeder circuit and to effect the closing of said switch onl when the potentials existing on both sides of the open terminals thereof have a predetermined magnitude and phase position.

42. In an alternating-current system of distribution, a workingcircuit, a plurality of transformers, feeder circuits for supplying energy to said working circuit throu h each of said transformers, a switch in t e secondary of each transformer, and an electrically closed relay means controlling each switch and subjected to energy flow corresponding in direction to the energy flow in the secondary of the corresponding transformer when the corresponding switch is closed and according to the potential difference across complementary line and load terminals when said switch is open, said relay means acting to 0 en its switch when the direction of energy ow in the secondary is reversed from normal and to close said switch only when the potential of the secondary circuit is greater than the potential of the working circuit.

Intestimony whereof I have afiixed my signature.

GRANVILLE E. PALMER.

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