US1799057A - Protective arrangement for electric installations - Google Patents

Description

March 31, 1931. u. MODIGLIANI PROTECTIVE ARRANGEMENT FOR ELECTRIC INSTALLATIONS Filed Dec: 6, 1923 -4 Shets-Sheet 1 M r 1931- u. MODIGLIANI ,7

PROTECTIVE ARRANGEMENT FOR ELECTRIC INSTALLATIONS Filed Dec. 6, 1923 4 Sheets-Sheet 2 gwq doz UMBERTO MOD/GL/A NI March 31, 1931. u MODIGLIANI 7 PROTECTIVE ARRANGEMENT FOR ELECTRIC INSTALLATIONS Filed Dec. 6, 1923 4Sheets-Sheet s I 11 III UMBE'HTO MOD/GL/AN/ March 31, 1931. u. MODIGLIANI PROTECTIVE ARRANGEMENT FOR ELECTRIC INSTALLATIONS Filed Dec. 6, 1923 4 Sheets-Sheet 4 I H H gwue/nliot UMBEHTO MOD/GL/AN/ FIG. 5

Patented Mar. 31, 1931 UNITED STATES UMBERTO MODIGLIANI, OF MILAN, ITALY IRO'IEC'JJIVE ARRANGEMENT FOR ELECTRIC INSTALLATIONS Application filed December 6, 1923, Serial No.

The present invention relates to a protective arrangement for electric installations operating in such manner as to control the opening of interrupters arranged so as to permit the separation from the installation of the parts of circuits wherein a derangement takes place. This arrangement consists substantially in the combination of a plurality of elementary relays grouped so as to form a combination of relays adapted to be considered as a multiple relay, each of which is actuated by any kind of electric action exerted thereon by the currents circulating in the installation. This action is of amperemetric character if the relay is actuated by a current the intensity of which is proportionalto the intensity of the current to be controlled; it is of voltmetric character if the relay is actuated by a current the intensity of which is proportional to the tension of the current to be controlled; and it is of watt-metric character it" the relay is actuated by two combined actions, one amperemetric and the other voltmetric, which gives a resultant proportional to the rate of flow of energy.

This arrangement is characterized by the combination of a plurality of elementary relays into a multiple relay, each elementary relay being actuated by any kind of electric action of the currents to be controlled, and said current-s may differ from one another as to their character, phase and frequency. Said elementary relayscomprise each an electric meter or measuring instrument adapted to give a mechanical action proportional to the tension or to the intensity or to the power, or to any other electric quantity of the current to be controlled, according to their winding being voltmetric or amperemetric or wattmetric; and means adapted to oper ate a switch interrupting said currents, when these currents, which normally must be balanced, i. e. in a predetermined ratio between each other, become unbalanced.

For this purpose there are provided means for mechanically connecting several relays with each other in such manner that when all of the currents energizing said relays are nearly balanced, that is, in a constant predetermined ratio between each other, said 679,025, and in Germany December 14, 1922.

means for operating the switches remain inoperative when on the other hand, one of said currents becomes unbalanced, so that its quantity (tension, strength, power be different from'that which is in said predetermined ratio with respect to the same quantity of the other currents, said means become operative and control the switch.

The invention also relates to a combination of a plurality of differential elementary relays forminga retarded operation multiple relay, with a plurality of interrupters and with means adapted to lock said interrupters when the multiple relays cause the starting of one of said control interrupters governing a circuit in which a derangement" has taken place, this locking ceasing only when said latter interrupter is open.

In order to construct the device, it is necessary that the circuits to be protected be provided with interrupters adapted to open by the passage of an auxiliary current into the opening electromagnet, this current being supplied by the relay at the proper moment.

The protective device of the present invention may be used with single lines or with a group of lines terminating at the same bus bars, or with machines or with lines connect-ed together in parallel at their two ends, and it is always formed of the same elementary device, but grouped differently according to the case.

Referring to the drawings:

Fig. 1 is a diagram of the mechanicalcombination of three elementary relays and a locking device. 7

F ig.. 2 is a diagrammatic showing of three elementary relays;

Fig. 3 is a diagrammatic showing of the protective arrangement "applied to three three-phaselines terminating at the same bus bars and constructed for opening the interrupters interdependently. y

Fig. 4 is a diagram of three three-phase lines connected in parallel to the same bus bars, with three multiple relays for opening the'interrupters when an unbalance occurs.

Fig. 5 is a diagram of three three-phase lines connected to the same bus bars operat ing in parallel with the current transformers connected together so as to effect automatic opening during an unbalance and for a predetermined value of the total current.

Fig. 1 shows three elementary relays R R and R and a locking apparatus M, connected rigidly on two supports T. The elementary relay, which is the most important device of this invention, is shown in each of the three parts of Fig. 2. The same reference characters designate the various elements in Figs. 1 and 2. The elementary relay com prises a metallic disc 11 mounted on a shaft 10 set in rotation by electro-magnet 12 and g 12 and is subject to the action of the permanent magnet 13 as in any ordinary electric meter. The shaft 10, which rotates in supports 14. is of two parts connected together by the joint 15, which permits the upper part to be raised while allowing it to remain operatively connected with the lower part by sliding on pins 16. The lower part of shaft 10 carries at its upper end a disk 15a to which pins 16 are secured. The lower end of the upper part of shaft 10 carries a disk 15?) which is provided with two holes for receiving pins 16. By this construction the two parts of the shaft are held against relative rotation, but the upper part may be moved axially with respect to the lower part. The upper part of the shaft carries an endless screw 17 whose threadhas an inclination lower than the frictional angle (irreversible screw) which may rotate shaft D, by means of the toothed wheel (gear) 21 and couple 21 and 21 when in mesh through the action of the magnetic clutch 22. The pitch of the thread on screw 17 is such that shaft D can be rotated by revolving shaft 10, but screw 17 cannot be rotated by revolving'shaft D. When the upper part of shaft 10 is raised by causes hereinafter set forth, contact 0 closes (Fig. 1, this is produced by raising lever 23 pivoted at 24:).

There may be mounted on the same shaft D two or more wheels 21 actuated bytwo or more elementary relays R and R ete., constructed and regulated in the same manner and traversed by currents in the same direc tion so as to rotate the endless screw 17 in the direction for which they would causethe upper part of shaft 10 to raise if wheels 21 were stopped, and which we call the positive rotational direction; if wheels 21 and 21 are in mesh, shaft D rotates at a velocity whichis a function of the currents, and if said currents are equal, nothing else will happen; but if the two currents become unequal, more exactly, if the current which acts on B becomes the stronger one, the shaft R will have a tendency to rotate more rapidly R; from above downwardly; but since the pitch of this screw is almost irreversible this force will have almost no effect on B Shaft D cannot rotate at a speed greater than that which R permits, and wheel 21 of R connected to shaft D will rotate at this same speed (in view of the ratios of the gears being equal) therefore, when the endless screw of R has a velocity greater than that of R it will appear as if wheel 21 were immovable and screw 17 of R rotates with a speed equa to the difference between the actual speed of R and the actual speed of R i. e., screw 17 moves upwardly on account of its thread revolving on teeth of wheel 21 and the upper part of shaft 10 raises and operates contact 0 which, completing the auxiliary circuit, operates the auxiliary elements which, in turn, open the interrupter which should be opened, as set forth more clearly hereinafter. The length of endless screws 17 is suchthat they remain engaged with wheels 21 even when the shaft is raised. If the elementary relays are traverses by currents so as to rotate in the direction opposite to that which we have discussed, that is to say in the negative rotational direction, and so long as the currents, and their driving couples, are equal, shaft D will rotate in the direction opposite that of the preceding case without operating any switch. But, if the current acting on R is less than the other, the endless screw of R, will have a tendency to rotate more slowly than that of R shaft D, actuated by R operates wheel 21 of R at a speed greater than it would ha Y if itwere merely actuated by the endless screw of R the endless screw of R which cannot, in its rotation, follow the passage of the teeth of wheel 21, will be raised with the upper part of shaft 10 from R making the contact 0. The same thing occurs if the motor couple acting on B becomes zero or changes direction.

The driving couple which electromagnets 1.2 exert on disc 11 and shaft 10 may be made proportional either to the tension or to the intensity or to the power of the current energizing said electromagnets. This depends on the windings of said magnets being voltmetric or amperemetric ones, or said magnets being coupled in order to give a wattmetric resultant. Said windings may, of course, be connected directly to the conductors of the electric installation one wishes to protect, or-there may be provided instru ment transformers, i. e., voltage and current transformers, for keeping the relays of the protecting arrangement removed from the high tension of the installations.

Where direct current is used it is necessary to add to the metallic disc 10 a suitable winding on the same shaft, the same as in dire t current meters.

The operation of the elementary relays is always differential, whether the rotation of the shaft be positive or negative, and whatever may be the number of elementary relays connected to the same shaft D. The ab- As has been stated, the absolute value .of the currents or of the energles which traverse the conductors is of no importance, and

only the unbalance between these values of different conductors produces the protective operation. g

' If it is desired to protect electric lines connected in parallel at their two ends the elementary relays should be grouped differently. Fig. 4 shows a station G from which depart three three-phase lines L L L connected to the same bus bars I, II and III; 1, 2, 3 are the conductors which pass to the elementary relays; A A A and B B B re spectively are the opening interrupters and electromagnets controlled by the elementary relays, either directly or through timing devices. Fig.5 shows the station F receiving the above mentioned lines L L L connected to the. same bars; 1, 2, 3 are the conductors passing to the elementary relays; A A A and B B B" respectively are the interrupters and. eleotromagnets centrolled by the elementary relays; the interrupters may also be opened by the electromagnets K described hereinafter. The nine elementary relays which should be mounted in each station are divided into three groups, and each group may be called a phase relay and comprises three elementary relays connected to three conductors (one for each line) which are of the same phase; if there are 01. lines in parallel each phase relay will have n elementary relays.

The elementary relays of the same phase are connected to the same shaft D and are subject to the action of block M and shaft H. For example, relays R 'R and R connected to the conductors of phase one, are associated with shaft D and controlled by a common locking magnet M on shaft Hr. Assuming that the energy flows from G to'F the elementary relays are provided with magnetic clutches and have. windings of the amperemetric type arranged for positive rotation at G, and for negative rotation at F, and are connected to the conductors by current transformers T. If thethree lines which connect stations G and F are in serviceable condition, and if interrupters A are closed, the three currents of each phase will be equal (assuming the lines being equal; in case they Weredifferent the windings of the elementary relays wouldbe suitably constructed) and the three elementary relays of each of the three phase relays would rotate at equal speeds Consequently, in station G, the current in Wire ,L becomes greater, since the sense of flow of current remains the same; in station F, since the senseof the short circuit current is inverted with respect to the normal current, there shall be an inversion of said :current, or, at leas t,.a reduction of it.

I have statedthat for carrying out such a protection of multiple feeder, the multiple relays must bearranged forpositive rotation, i. e., operation through excess of current, at station G and for negative rotation, i. e., operation through reduction of current, at station F. Indeed,in these conditions at station G the above-mentioned increase ofcurrent of wire L with respect to wires L" and L makes relay R close contacts C and operate switch A of line L, thusdisconnecting-these lines fromthe bus bars. At station F, where the relays rotate negatively, the above-mentioned reduction or inversion of current in Wire L makes the relay R close its contacts and operate switch A thus disconnecting line L from the bus bars. Now the shortcircuit is completely isolated and the whole system becomes balanced again, while. each of the unfaultylines assumes a part of the load previously carried by the isconnected line. 1

Generally, when such a fault on a phase of a line occurs which results in an abnormal current flowing in the. conductor of that phase of that line, the conductors of the same phase of the other lines become traversed by an abnormal current, although less than that of the faulty line, since they are connected to the same bus bars.

In the above case, relays R R of these conductors begin to raise, like relay R' but with a lesser speed, so that contacts C become closed before relays R R have reached their upper positions. As soon as 0 2 close the tripping circuit, locking devices M become energized and prevent any further raising of relays R R In such manner, there is avoided the disconnecting of lines L and L on account of the transient unbalance and overload which occurs upon a fault on line L but which disappearsas soon as faulty line L isdisconnected, from the bus bars.

As soon as said faultyline is disconnected, the current therein drops to zero and the magnetic clutches of the relays energized by said line disconnect said relays from the common shaft D. Thus the multiple relay continues to rotate and protect the lines still connected with the bus bars and carrying currents. At the same time, locking means M become de-energized and allow anyrelay to close contacts C; but now in general the remaining lines will be balanced; i. e., all of their conductors wijll carry-about the same current, and no relay will raise. Thus a ers in which the energy flows sometimes in one sense and sometimes in the other, one may carry it out simply on energizing wattmetrica-lly each relay. If, for example, one has two stations G and F and three feeders L L and L connecting said stations and carrying current alternatively from G to F and from F to G, one may provide each of said stations with a multiple relay as described above, comprising a relay energized proportionally to the rate of flow of energy in a conductor, and electromagnetic clutches for disconnecting a relay from the shaft D when said relay stops, its conductor being disconnected from the system. Thus at the station supplying energy operation of the line breakers will occur on account of an excess of current in any conductor, and at the receiving station on account of avdrop of the received current or of a reversal of its sense of flow, what actually occurs in case of a fault protection will then be assured in any case.

The above mentioned protection may function only by reason of unbalance between the conductor currents, but not for excess load. If it is desired to open the interrupters also for a predetermined load, and where current transformers have been mounted for said protection,the secondaries of the transformers of the same phase may be connected in parallel through the winding of maximum relay MR, which causes all the mterrupters to open at the same time, by means of electromagnets K, connected in circuit with battery Ba. The advantage of this apparatus is that of op eration for the same excess load for which it is adjusted, whatever may be the number of the lines in operation.

What I claim is:

'1. The combination, in an electrical power transmission system including a plurality of parallel conductors passing in groups through switches, electroresponsive devices each comprising an electric meter operatively energized by one of said conductors, a shaft operatively connected with said meter and adapted to be moved by said meter at a speed in direct relationship with an electric quantity of the electricity flowing in said conductor, so that said speed being compelled to vary results in a torque proportional to said quantity being applied to said shaft, a plurality of said devices arranged in a group, means adapted to connect mechanically allv of the shafts of a group of said devices with each other and adapted to be moved by said shafts which rotate at speeds in a constant predetermined ratio between each other, but incapa- "le of driving said shafts, so that a shaft tending to vary its speed results in said torque being applied to said shaft, means controlled by said shafts and adapted to operate the switches of a group of conductors when the shaftof an electroresponsive device con: nected wit-h a conductor of said group rotates at a speed which diflers from that corresponding in the predetermined ratio to the speeds of the shafts of the other electroresponsive devicesof the same group, means adapted to regulate the amount of the torque exerted'on said shaft by which the operation of said switches occurs.

2. The combination, in an electrical power transmission system including a plurality of parallel conductors passing in groupsthrough switches, electroresponsive devices each comprising an electric meter operatively energized by one of said conductors, a shaft operatively connected with said meter and adapted to be moved by said meter at a speed in direct relationship withan electric quantity of the electricity flowing in said conductor, so that said speed being compelled to vary results in a torque proportional to said quantity being applied to said shaft, a plurality of said devices arranged in a group, means adapted to connect mechanically all of the shafts of a group of said devices with each ed with a conductor of said group rotates at a speed which differs from that corresponding in the predetermined ratio to the speeds of the other and adapted to be moved by said shafts V shafts of the other el-ectroresponsive devices i of the same group, means adapted to regulate the amountof the torque exerted on said shaft by which the operation of said switches oc curs, means adapted to lock the electroresponsive devices against operation when one of said devices has operated.

V 3. The combination, in an electrical power transmission system including a plurality of parallel conductorspassing in groups through switches, electroresponsive devices each comprising an electric metenoperatively energized by one of said conductors, a shaft operatively connected with said meter and adapted to be moved by said meter at, a speed in direct relationship with an electric quantity of the electricity flowing in said conductor, so that said speed being compelled stant predetermined ratio between each other, butincapable of driving said shafts, so that a shaft tending to vary its speed results in said torque being applied to said shaft, means controlled by said shafts and adapted to 0p erate the switches of a group of conductors when the shaft of an electroresponsive device connected with a conductor of said group rotates at a speed which differs from that corresponding in the predetermined ratio to the speed of the shafts of the other electroresponsive devices of the same group, means adapted to regulate the amount of the torque exerted on said shaft by which the operation of said switches occurs, means adapted to lock the electroresponsive devices against operation when one of said devices has operated,

" and means energized by an electric quantity of the electricity flowing in all of said conductors and arranged to operate all of said switches when said electric quantity exceeds a predetermined value.

4. The combination, in a power supply in cluding a plurality of parallel conductors passing by groups through switches, electroresponsive devices each comprising-an electric meter energized by one of said conductors, a shaft arranged to be driven by said meter at a speed in direct relationship with an electric quantity of the electricity flowing in said conductor so that its speed bein compelled to vary results in a torque applied to said shaft proportional to said quantity, a plurality of said devices arranged in a group, a telescopic oint for connecting each of said meters with its shaft while permitting a raising of said shaft, a worm mounted on each of said shafts, a wheel meshing with each of said worms and arranged to be driven by said worm, but incapable of driving said worm so that a shaft carrying said worm tending to vary its speed results in said torque beingapplied to said shaft, another shaft connecting all of said wheels of said clectroresponsive devices of a group with each other, and arranged to compel said wheels to rotate at speeds which are in a constant predetermined ratio with each other, so that a shaft rotating at a speed which is not in said predeter- 'mined ratio with the speeds of the other shafts of the same group raises on account of its worm revolving on the gear of said wheel meshing with it, a tripping relay for each of said'switches having an energizing circuit, a pair of contacts in said circuit operated by said device tocomplete said circuit when said electric quantity of the electricity flowing in said conductor differs from a constant predetermined ratio with the same electric quantity of the electricity flowing in the other conductors energizing other devices of the same group, means to regulate the amount of the torque exerted on said firstnentioned shaft by which said raising occurs, means energized by said circuit and arranged to prevent the raising of said shafts when one of said shafts is lifted and until the switch operated by it has completed its operation.

5. The combination, in a power supply including a plurality of parallel conductors passing by groups through switches, electroresponsive devices each comprising an electric ampere-hour meter energized by one of said conductors, a shaft adapted to be driven by said meter at a speed proportional to the rate of flow of current in said conductor, a plurality of said devices in a group, a telescopic joint for connecting each of said meters with its shaft while permitting a raisin of said shaft, a worm mounted on said shaft, a wheel meshing with said worm and arranged to be driven by said worm, but incapable of c driving said worm, another shaft arranged to connect all of said wheels of said electroresponsive devices ofa group with each other, and arranged to compel'said wheels to rotate at speeds which are in a constant predetermined ratio with each other, so that a meter shaft rotating at a speed which is not in said predetermined ratio with thespeeds of the other shafts raises on account of its worm revolving on the gear of said wheel meshing with it, a slow acting tripping relay'for each of said switches having an energizing circuit, a pair of contacts in said circuit operated by a raising of a meter shaft to complete said circuit when the flow of current in said conductor differs from a constant predetermined ratio with the. flow of current in the other conductors energizing meters of the same group of devices, means to regulate the amount of said difference between the currents by which operation of said contacts occurs, means energized by said circuit and arranged to prevent the raising of said shafts when one of said shafts is lifted and until the switch operated by it has completed its operation, and means energized by all of said conductors and arranged to operate all of said switches when the rate of flow of current in a conductor exceeds a predetermined value.

6. In combination, a feeder provided with several conductors arranged in parallel, a switch for said feeder, electro-responsive devi'ces'each comprising an electric meter energized by one of said conductors, a shaft connected with said meter and adapted to be driven by said meter at a speed in direct relationship with an electric quantity of the electricity flowing in said conductor, so that its motion being compelled to vary results in a torque proportional to said quantity being applied to said shaft, said devices being arranged in a group, means adapted. to connect mechanically all of the shafts of said devices with each other, and adapted to be moved by said shafts, but being incapable of driving said shafts, so that a shaft tending to vary its speed results in sai-dtorque being applied to it, means controlled by said shafts and adapted to operate said switch when the speeds of said shafts differ between each other, means adapted to regulate the amount of the torque exerted on said shaftby which operation of the switch occurs and means energized by said feeder and adapted to operate said. switch when said electric quantity of the electricity flowing in said feeder exceeds a predetermined value. v

7 In combination, a feeder provided with a number ofconductors arranged in parallel, a switch for said feeder, electroresponsive devices each comprising an electric meter energized by one of said conductors, a shaft arranged to be driven by said meter at a speed in direct relationship with an electric quantity of the electricity flowing in said conductors, so that its speed beingcompelled to vary results in a torque proportional to said quantity being applied to said shaft, said devices being arranged in a group, for connecting each of said meters with its shaft while permitting a raising of said shaft,

a worm mounted on said shaft, a wheel arranged to be driven bysaid worm but incapable of driving said worm, so that a shaft carrying said worm tending to vary its speed results in said torque being applied to said shaft, another shaft arranged to connect all of said wheels of said electroresponsive devices with each other, and arranged to coinpel said wheels to rotate at speeds which are in a contant predetermined ratio with each other, so that a first mentioned shaft rotating 7 at a speed which is not in said predetermined ratio with the speeds of the other shafts raises on account of its worm revolving on the gear of said wheel meshing with it, a tripping relay for each of said switches having an energizing circuit, a pair of contactsin said circuit operated by the raising of a first mentioned shaft, and arranged to complete, said circuit when said electric quantity of the electricity flowing in a conductor of said feeder differs by a predetermined amount from its normal value which is in a constant predetermined ratio with the same electric quantity of the electricity flowing in the other conductors, means adapted to regulate'the amount of the torque exerted on saidr firstmentioned shaft by which said raising occurs, and means energized by said feeder and adapted to operate said switch when said electric quantity of the electricity flowing in said feeder exceeds a predetermined value.

8. In combination, a feeder provided with a number of conductors arranged in parallel,

a telescopic j oint feeders being a switch for said feeder, electroresp onsiie deices each comprising an electric ampere-hour meter op-eratively energized by one of said conductors, a shaft operatively connected with said meter and adapted to be moved by said meter at" a speed proportional to the rate of flow of current in said conductor, said devices a telescopic being arranged in a group,

said meters shaft rotatingat a speed which is not in said predetermined ratio with the speeds of the other shafts raises on account of its worm revolving on the gear of said wheel meshing with it, a trippingrelay for each ofsaid switches having an energizing circuit, a pair of contacts in said circuit operated by the raising of a first mentioned shaft and'arranged to complete said circuit when the rate of flow of current in a conductor of said feeder differs fora predetermined ratio with the rate of how of current In the other conductors, means adapted to regulate the amount of said dii'erence V each conductor comprising an electric meter energized by said conductor, a shaft connectedwith said meter and adapted tobe moved by said'meter at" a speed in direct'relationship with an electric quantity of the electricity flowing in said conductor so that its motion being compelled to vary results i in a torqueiproportional to said quantity being applied to said shaft, a plurality u of devices energized by conductors of different arranged to connect mechanically all of the shafts of said devices of a group and adapted to be driven by said shafts which rotate a speeds in a constant predetermined ratio between each other, butbeing incapable of driving said shafts, so that a shafttend- 'ing to vary itsspeed results in a' torque be ing applied to said-shaft, means-controlled by said shafts and adapted to operate the at raising of I predetermined amount from its normal value which is in a constant arranged in a group, means said feeder and adapted to operate said tricquantity in the electricity flowing in switch ofa feeder-when the speed of the shaft of the electroresponsive device connected with a conductor of said feeder differs from said predetermined ratio with respect to the speeds of the shafts of the other devices of the same group, means adapted to regulate the amount of the torque exerted on said shaft by which the operation'of the switch occurs.

10. In Combination, an electric. power transmission system including a plurality of feeders-each provided with a switch and each comprising a number of conductors arranged in parallel, an electroresponsive device for each conductor comprising an electric meter energized by said conductor, a shaft connected with said meter and adapted to be moved by-said meterat a speed in direct relationship with an electric quantity of the electricity flowing in said conductor, so that its motion being compelled to vary results in a torque proportional to said quantity'being applied t'o said "haft, a pluralityof said devices energized by conductors of different feeders being arranged in a group, a telescopic joint for connecting each of said meters with a shaft while permitting a raisingof said shaft, a worm mounted on said shaft, a wheel meshing with said worm and arranged tobe driven by said worm, but incapable of driving said worm, so that a shaft tending to vary its speed results in said torque being applied to said shaft, a shaft for each group of devices, means operatively energized by said conductor and arranged to operatively connect said second mentioned shaft with said wheel when said conductor carries an electric current, means operatively connected with said second shaft and said wheels and adapted to compel said wheels to rotate at speedsin a constant predetermined ratio with each other, so that a first mentioned shaft rotating at'a speed which is not in said predetermined ratio with-the speeds of the other shafts raises on account of its worm revolving on the gear of said wheel -meshing with it, a slow acting tripping relay for each of said switches having an ener- -gizing circuit, a pair of contacts in saidcir cuit operated by the raising of a first mentioned shaftand arranged to complete said circuit when said electric quantity of the a conductor passing through said switch differs from said predetermined ratio with respect to the same elecother conductors of the same group, means adapted to regulate the amount of the torque exerted on said first mentioned shaft by which said raising occurs, means arranged to prevent the raising of said shafts when one of said shafts is lifted anduntil the switch operated by it has c ompleted its operation, and means energized by all of said conductors and arranged to operate all of said switches when said tor,

shaft while permitting a with each other, so

other shafts raises on account electric quantity exceeds a predetermined value.

11. The combination, transmission system including a in an electric power plurality of feeders each provided with a switch and each comprising a number of conductors arranged in parallel, an electroresponsive device for each conductor comprising an electric ampere-hour meter energized by said conduca shaft connected with said meter and adapted to be moved by said meter at a speed proportional to the rate of flow of current in said conductor, a plurality of said devices energized by conductors of different feeders being arranged in a group, a telescopic joint for connecting each of said meters with a raising of said shaft, a worm mounted on said shaft, a wheel meshing with said worm and arranged to be driven by said worm, but incapable of drivmg said worm, another shaft for each group of devices, flowing in said conductors to connect said second mentioned shaft with a wheel when the rate of flow of currentin said conductors exceeds apredetermined amount, means connecting said second shaft and said wheels and adapted'to compel said wheels to rotate at speeds in a constant predetermined ratio that a first mentioned speed which is not in said predetermined ratio with the speeds of the of its worm revolving on the gear of said wheel meshing with it, a slow acting tripping relay for each of said switches including an energizing circuit, a pair of contacts in said circuit operated by the raising of a first mentioned shaft electromechanically connected with a conductor passing through said switch, and arranged to complete said circuit when the rate of flow of current in said conductor differs by a predetermined amount from a constant predetermined ratio with respect to the rate of flow of current in the other conductors of the same group, means adapted to regulate the amount of said difference between the currents by which operation of said contacts occurs,means energized by said circuit and arranged to prevent the raising of said shafts shaft rotating at a 'when one of said shafts is lifted and until the means operated by the current

Images