US1237973A - Automatic substation. - Google Patents

Description

50 tors,

UETTED sTATEs yPATENT oEEICE.`

EDWARD TAYLOR, or CHICAGO, InLINo'Is,Ass1GNoR 'ro GENERAL ELECTRIC COMPANY,

A CORPQTION 0F NEW YORK.

AUTonrATIC- sUBsTATioN.

To4 all whom it may concern:

tions of the type employing a rotary transformer which is adapted to interconnect a supply circuit and a distribution circuit.

Automatic substations of this type .are particularly 4.applicable to electric railway systems where the schedule -of operation is such that the substation is only needed during a small portion of the whole time. Since on the distribution circuit. The disruptingof heavy currents frequently causes sudden.

- ing' `of no attendant is required, all expense in this connection is avoided, and, in addition, the

light load losses attendant upon the operation of the ordinary substation are entirely eliminated. One object of my invention, then; is to produce an improved construction of automatic substation of this type. y

In connection with such a substation, I have found it to be particularly important that the sequence of operation of the vari? ous switches controlling the rotary transformer shall be exactly determined, and also that the intervals between the operation of the various switches should be properly controlled. It is another object of my invention to provide apparatus for an automatic substation whereby the sequence of operations and the intervals therebetween shall be mechanically and positively determined.

It has been found that the ordinary circuit-breaker interposed between the rotary transformer andthe distribution circuit is not in'all cases a satisfactory means of protection for the substation from overloads induced voltages in the distribution circuit which may exceed 200%.of the normal voltage. Where the distribution circuit is a railway trolley, such voltages may cause flashing-over of the commutators and moor may puncture the motor lnsulation. On the other hand, the simultaneous startseveral cars within the zone of operation' of the substation may produce such Speeication of Letters Patent. j

'ployed and the connections used for my an overload that the ordinary circuit-breaker wouldbe blown out. In the usual arrangement, thecars would then be fed withl current from a distant station, but at a greatly reduced Voltage, their acceleration would, therefore, be greatly decreased, and, asa consequence, the counter-electromotive force produced would also be decreased. Suppose, then, that the operator at the substatin closes thecircuit-breaker, and throws the normal voltage on the trolley line. The motor equipment is not' in a condition to receive such a voltage,'and, as a consequence, .severe trouble may result. It is accord-l Ingly, another object of my vinvention to provide means of overload protection which shall overcome these difiiculties and effectively protect thei substation and the dis tribution circuit.

My invention will be more readily understood from the following description, taken in connection with the accompanying drawing, in which the single figure is a diagrammatic view illustrating the apparatus emM tomatic substation. The supply circuit A. C. is adapted to be Patented Aug. 21, 1917, Application ined July 7, 1915. serial No. 33,620. l

`nals of the-rotary transformer R. T., which as shown is a rotary converter, bymeans of lthe oil switch O. S., through the transformer T and either sone or the other of the -of the usual construction, and is provided with the shunt field windings a, b and c, and with the series field windingv d. This series field winding is arranged so that it may be shunted by means vof a resistance e. The direct current terminals ofthe rotary converter are arranged to be connected to the distribution circuit .D. C., through a series 4of resistances 50 and the coils of certain relays, to be later described.

This apparatus is arranged to be controlled by *mea-ns of electromagnetic switches, most vof which are energized in sequence by means of a controller C. The l .switches R and S. The rotary converter is function of the controller is to mechanically have illustrated this\controller` as being' made up of fixed contact fingers leading to on a single distribution circuit.

the coils ofthe various electromagnetic switches, and of a cylindrical drum carrying metallic contacts, by means of which the various fingers may be interconnected in the desired' manner and in the desired sequence. This form of vcontroller is well known in the art, and no further description thereof is deemed herein necessary.

For the purpose of rotating the cylindrical drum of the controller C, I have illustrated a motor M, which is mechanically connected thereto. Automatic means are then provided for controlling this motor, so that preferably the station will be operated inaecordance with the load conditions of the distribution circuit D. C.

When the station is applied for use in connection with an electric railway, I find it convenient to make this automatic apparatus of such a form that the station will be started when the voltage of the distribution circuit decreases below a predetermined value, and will be stopped when the power transferred by the rotary transformer is less than a predetermined amount.

It is believed that the cooperation and function of the various elements will be more readily understood when considered in connection with their mode of operation,

and to this end I will describe the operation of my substation when the load conditions of the distribution circuit are such as to require its use.

Let us assume that the distribution circuit is energized, but that .its voltage is considerably below normal, say, for example, 400 volts. A relay l will be energized, and immediately closes its upper contacts. The lower contacts of this relay are connected to the magnetic core by means of a spring, and their closing is delayed by means of a suitable retarding device such as a dashpot, which may be suitably vdesigned so that the lower contactsl will close after any desired interval. The particular construction of this relay is required only when several automatic substations of this type are arranged In that case, it is desirable that the stations shall not all be started at the same time,as might happen at the beginning of a'day, when the distribution circuit is first energized, but that their starting should be retarded for definite intervals. The contact-making voltmeter 2, which is responsive to the voltage of the distribution circuit, will fall to a position so that its movable arm makes contact with the upper fixed contact point, and

thereby energize the relay 3. This relay is thereupon raised, and completes a holding circuit through its upper contacts. At the same time it energizes the potential coil g of the master relay 4, and raises the same to close a circuit through the sliding contacts and the conta-cts of the relays 23 and 24 for energizing the relay 5.v This relay will then be lifted and thereby close a circuit through the controller to energize the relay 6. The energizationof this relay will supply direct current to the motor M and to the brake coil B in series therewith. The brake coil B is used in connection with an electromagnetic brake, so designed that when the The energization of the relay 8 will then energize the relay 7 through the contacts of the controller, and this, in turn, will then energize the coil l0 of the starting switch S, and thereby supply alternating current energy at a reduced potential to the terminals of the rotary transformer lt. T. This will start the' rotary transformer in motion. Further movement of the controller to the position4 o will simply insert a resistance 26 in series, through the interlock contacts of the oil switch O. S., with the relays 8 and 9. The resistance 26 will be so proportioned that sufficient current will flow in this circuit to hold these relays closed, but will be of such value that the current supplied will not be suiiicient to initially close the relays. In the event, therefore, of a momentary interruption of power on the distribution circuit during the subsequent cycle of operations of the controller C, the relays 8 and- 9 will open, and cannot be closed until the controller returns to its original neutral position Obviously, the opening of the relay 9 Will denergize the closing coil of the oil switch O. S., allowing the saine to open, and thereby prevent further acceleration of the rotary transformer R. T. Upon the return of normal voltage on the distribution circuit, the inaster relay 4 will drop to its lower positiii" and thereby energize the relay'and cause the controller to be returned to the neutral position a'. The drum of the controller now moves ahead for several seconds, without altering the existing conditions. This interval gives sufficient time to allow the acceleration of the rotary transformer. lVhen the controller position p is reached, however, the field break-up switch 11 will be energized, thereby connecting the shunt field windings (ab, and c, in series with one another, and the resistance E. R. across the distribution circuit D. C. This provision of a switch for breaking up the shunt field windings of a rotary transformer into se\- eralportions is well known in the art, and is for the purpose of reducing the voltage which might be induced thereln during the starting period. `When the controller position g is reached, the switch 12 will be energized, and short circuit the resistance E. R., thereby applying the full voltage of the distribution circuit .to the shunt field of the rotary transformer'. Between the controller positions g and r, the relay 7, and, consequently, the magnet l0 are denergized, thus causing the opening of the starting switch S. At the position r, the magnet 18 of the running switch R will be energized, and the switch closed.

It will be noted that the switches R and S are electrically interlocked, and that each one is provided with a resistance which is inserted in series with its coil as soon as the corresponding switch is closed. The provision of these resistances cuts down the current supplied to the coils 10 and 13, and decreases the sparking at the contacts of the controller C when their circuits are opened. When the running switch R is closed, the full voltage of the supply circuit A. C. will beapplied to the rotary transformer. At the next position s of the controller C, the switch 14 will be energized, thereby shunting the series field cl of the rotary transformer by means of the resist ance e. At the position t, the switch 15 will be energized through interlocks on the switches 11, ,12, and 13, and will thereby connect the direct current terminals of the rotary transformer to the distribution cir-- cuit through the resistances 50, the holding coilv k of the master relay a, and the current coil of a reverse current relay 22. At the steps u, 'u and w the switches 1.6, 17 and 1S will be energized in turn to successively short-circuit portions of the resistance 50. The energizing circuits of these relays are controlled by means of relays 19, 20, and 21, which are responsive to the power transferred by means of the rotary transformer, and, in this case, are energized from a current transformer on the alternating current side thereof. rlhe relays 19, 20, and 21 are so designed that they are responsive to dierent values of current, and will, consequently, open in succession as the power transferred exceeds certain predetermined values, corresponding to the settings of these relays. The function of these relays will be later considered more at length. Then the position w is reached, the energizing circuit of the relay 6 is broken, thereby stopping the controller at this, running position. Power will now be supplied to the distribution circuit D. C., and the.`

voltage of said circuit will be determined by the Voltage of the direct current terminals of the rotary transformer. As soon as this voltage reaches the normal voltage of the distribution circuiti, lsay 550 volts, the mov1 able arm of the contact-making voltmeter 21 will touch its lower fixed contact and short'- circuit theirelay 3, thereby dropping out the same and denergizing the potentialcoil g yof the master relay t. The master relay will, however, be retained in its upper position by means of the holding coil 7L so long as the current therein exceeds a predetermined value. The reverse current relay 22 is so designed that when the power transferred exceeds the predetermined value by which the holding coil t is designed to hold up the master relay 4, its moving contact will be moved to the left, thereby inserting a resistance 22 in series with the coil of the contact-making voltmeter 2. rThis will so reduce the voltage on the contactmaking voltmeter that its movable arm will immediately touch the upper fixed contact and thereby renergize the relay 3 and the potential coil of the master relay 4. The holding coil i and the reverse current relay 22, therefore, operate toward the same end, to wit, that the substation shall be retained in operation so long as the power transferred exceeds some predetermined minimum value which makes it desirable to operate the same. Although the relay is constructed as a reverse current relay, it does not function in the manner of the ordinary reverse current relay, and its only action upon a reversal of current will be to short circuit the resistance 22 so that the full voltage of the distribution circuit will be impressed upon the contact-making voltmeter 2. W'hen the conditions of the load on the distribution circuit are such that the power transferred no longer exceeds this certain minimum value, then the master relay et will, after the expiration of an interval determined by the setting of the dashpot attached thereto, move to its lower f osition and thereb energize through the contacts of the controller, the switch 25. Power will, therefore, be again supplied to the motor M and brake coil B, and the controller will be moved from the position w to the neutral position where the circuit leading to the switch 25 will be broken and the motor and the controller be stopped. rlhe substation is then in condition to be again started as conditions may require.

For the protection of the apparatus in- V,

volved, certain relays 23 and 24, have been provided. Iln case of a failure of voltage on the supply circuit A. C., the contacts o f the relay 23 will open, and thereupon den energize the relay 5 and, in turn, the other electromagnetic switchesl of the substation. If, on the other hand, the power transferred through the substation exceeds a predetermined amount, the relays 24 will be energized and will likewise open the circuit of the relay 5. that the substation should continue lin operation and deliver aicertain small amount of current, without being\entirely discon` It may, however, be desirable nected from the distribution and supply circuits. To this end the relays 19, 20 and Q1 have been so arranged that as the power transferred, and hence the current in the alternating current leads, exceeds a certain value, they will open successively and deenergize the magnets 16, 17 and 18 in turn, thereby inserting one or more sections of the resistance 50 between the rotary transformer and the distribution circuit. These resistances will be so dimensioned that their insertion will substantially reduce the power transferred, and at the same time allow the substation to continue in operation and supply some power.

From oscillograph tests, it has been determined that short circuits on a trolley line of limited capacity do not reach their maximum value instantly, but build up to their maximum in approximately five-tenths of a second. Before the expiration of this i'iveetenths vof a second, or in say, wo or three-tenths of a second, one or mor of the relays 19, 20 and 21 will have come into operation and inserted portions of the resistance 50 between the rotary transformer and the distribution circuit. These relays are provided with dashpots, so that they may open quickly, but will not close until after the expiration of a certain interval of time. In actual practice, it will be found desirable to so adjust the setting of the relay 19 that it will open when approximately 10% overload is reached, while the relays 20 and 21 will open at 25% and 50% overload, respectively. Since the setting of the relay -19 is comparatively low, as contrasted with the necessary high setting of an equivalent circuit breaker, these relays and the short-circuiting switches 16, 17 and 18 controlled thereby are beginning to open before the short circuit has reached its maximum value. p

' It will thus be seen that I have provided a substation which is entirely automatic, and

is operated in accordance with the load conditions of the distribution circuit. I have furthermore, provided a novel and eflicient method of protection against overload. I aim to cover in the appended claims not only the particular form of the apparatus which I have herein described, but also any modifications thereof which do not depart from the spirit and scope of my invention.

lVhat I claim as new and desire to secure by Letters Patent of the United States, is

1. In combination, a supply circuit, a distribution circuit, a rotary transformer,

means for connecting said transformer to.

said circuits, means for'mechanically controlling the sequence ofoperation of said connecting means, and automatic means controlling' the operation of said mechanical controlling means.

tribution circuit, a rotary transformer, means for connecting said transformer to said circuits, means for mechanically controlling the sequence of operation of said connecting means, and means responsive to the electrical condition of the distribution circuit controlling the operation of said mechanical controlling means.

3. In combination, a supply circuit, a distribution circuit, a rotary transformer, means for connecting the same to said circuits, means responsive to the voltage of the distribution circuit controlling said connecting means, and means responsive to the power transferred between said circuits controlling said voltage responsive means.

el. In combination, a supply circuit, a distribution circuit, a rotary transformer, means for connecting the same between said circuits, means responsive to a low voltage on the distribution circuit controlling said connecting means, and means responsive to the power transferred between said circuits arranged to produce the effect of low voltage on said voltage responsive means when the power transferred exceeds a predetermined amount.

5. In combination, a supply circuit, a distribution circuit, a rotary transformer, means for connecting the same between said circuits, means responsive to the voltage `of one of said circuits controlling said connecting means, and means for delaying the action of said voltage responsive means for a predetermined time.

6. The combination with a supply circuit and a distribution circuit, of a rotary transformer adapted to be connected therebetween, automatic means responsive to a decrease in the distribution circuit voltage for connecting the transformer to said circuits, means responsive to the distribution circuit voltage for controlling the operation of said automatic means, and means for delaying the operation of said last named means.

7 In combination, a supply circuit, a distribution circuit, a rotary transformer, electromagnetic means for connecting the same` to one of said circuits, arelay controlling the supply of energy to said electromagnetic means, a controller arranged to energize said relay, and a resistance adapted to be connected in series with said control relay, said controller being constructed and arranged to short circuit said resistance during a short part of its range of movement.

8. In combination, a supply circuit, a distribution circuit, a rotary transformer, electromagnetic means for connecting the trans former to each of said circuits, relays controlling the supply of energy to said means, a resistance, and a controller adapted to en* ergize said relays independently of said resistance during a portion of its range of m vement and to energize said relays through said resistance during another portion of itsrangeof movement. 9. In combination, a supply circuit, a distribution circuit, a rotary transformer, a

plurality of electromagnetic switches for controlling the starting of said transformer, andQ-,forfconnecting the same to said circuits, a""in'otoroperated controller for mechanically determining the. sequence of operation of said electromagnetic switches, said controller being-arranged to open the circuit of 'its driving motor when the transformer has been connected to said circuits.v

10. In combination, a supply circuit, a distribution circuit, a rotary transformer, a plurality of' electromagnetic switches for starting said transformer and for connecting the same to said circuits, means responsive to the electrical condition of the distribution circuit for moving said'controller to the position for connectingsaid transformer to said circuits, and means responsive to the power transferred between said circuits for moving said controllerto its initial position.

11.' In combination, a supply circuit, a distribution circuit, a rotary transformer,- electromagnetic means for starting said transformer and connecting the same to said circuits, an automatically operated controller forvenergizing said electromagnetic means, a plurality of resistance members connected in series, between said transformer and said distribution circuit, and electromagnetic means arranged to shortcircuit said resistance members, said controller being arranged to energize said shortcircuiting means in sequence.

12. In combination, a supply circuit, a distribution circuit, a rotary` transformer, electromagnetic means for vstarting said transformer and connecting the same to said circuits, an automatically operated controller for energizing said 'electromagnetic means, a plurahty of resistance members connected in series between said transy former and said distribution circuit, electromagnetic means arranged to short-circuit said resistance members, said controller being arranged to energize said short-circuiting means in sequence, and means responsive to the power transferred between said circuits controlling said short-circuiting means.

13. In combination, a supply circuit, a

distribution circuit, a rotaryfitransformer,

v"s'aid controller being constructed and arranged to prevent the further energization of said electromagnetic means through said relays after a momentary interruption of power during the movement of said controller.

14. In combination, a supply circuit, a distribution circuit, a rotary transformer, means for supplying a reduced voltage from one of said circuits to said transformer, means for supplying the full voltage of said circuit to said transformer, andautomatic means for mechanically controlling the sequence of operation of said means.

15. In combination, a supply circuit, a distribution circuit, a rotary transformer, means for supplying a reduced voltage from one of said circuits to said transformer, means for supplying the full voltage of said circuit to said transformer, said means being arranged to prevent their simultaneous closure, and automatic means for mechanically controlling the sequence of operation of said means. v

16. In combination, a supply circuit, a distribution circuit, a rotary transformer having a field winding, means for energizing said winding from said distribution circuit, means for starting said ltransformer and for connecting to each of said circuits, andl automatic means for mechanically controlling the sequence of o-peration of said means.

17. The combination with a supply circuit and a distribution circuit, of a rotary 'transformer adapted to be electrically connected therebetween, said transformer having a sectional ield winding, a field resistance, an

armature resistance, and automatic means operable, upon a decrease in the distribution circuit voltage, t0 start said transformer from the supply circuit through a low voltage connection, then to connect the sections of said field winding in series with each other and said field resistance across the distribution circuit, then to short circuitsaid field resistance, then to operate said transformer from the supply circuit through a high voltage connection, and then to connect said transformer to the distribution circuit through said armature resistance and subsequently gradually render said arma- 4ture resistance ineffective.

18. The combination with a supply circuit and a distribution circuit, of a rotary transformer provided with a shunt field winding comprising a plurality of sections and adapted to be electrically connected between said circuits, a shunt field resistance, an armature resistance, and automatic means operable in response to an electrical condition of the distribution circuit to start said rotary transformer from the supply circuit through a low voltage connection, then to connect the sections of said fieldl winding in series with each vother and with said shunt field resistance across the distribution circuit," then -to short circuit said field resistance, then to connect said rotary transformer to the supply circuit through a high voltage connection, and then to connect said rotary transformer to the distribution circuit through said armature resistancevand subsequently shortvcircuit the armature resistance. A

19. The combination with a supply circuit and a distribution circuit, of a rotary transformer provided with a field winding comprising a plurality of sections and adapted to be electrically connected between said circuits, a shunt field resistance, an armature resistance, and automatic means operable in response to an electrical condition of the distribution circuit to start said rotary transformer from the supply circuit through a low voltage connection, then to connect the sections of said field winding in series with each other and with said shunt field resistance across the distribution circuit, then to short circuit said fieldrey sistance, then to connect said rotary transformer to the supply circuit to supply power thereto through a high voltage connection, and then to connect said rotary transformer to the distribution circuit through said armature resistance and subsequently short circuit e armature resistance, said auto.-

' matic means being operable upon a failure of the supply voltage or the distribution circuit voltage to disconnect said rotary transformer from the supply circuit and the distribution circuit.

Q0. The combination with a supply circuit and a distribution circuit, of a rotary transformerv adapted to be electrically connected therebetween, automatic meansoperable in response to an electrical condition of the distribution circuit to effect the connectionof said rotary transformer to the supply circuit and to the distribution circuit, and means coperating with said automatic means to effect the disconnection of said rotary transformer from the supply'circuit and from the distribution circuit upon a failure of voltage in either of said circuits.

2l'. The combination with a supply circuit and a distribution circuit, of a rotary transformer adapted to be electrically connected therebetween, automatic means operable in response to an electrical condition of the distribution circuit lto effect the connection of said rotary transformer to the supply circuit and to the distribution circuit, means cooperating with said automaticineans to effect the disconnection of said rotary transformer from the supply circuit` and from the distribution circuit upon-a failure of voltage in either of said circuits, a Variable resistance adapted to be connected in circuit between said rotary transformer and the distribution circuit, and means responsive to the power supplied to the rotary transformer to control the insertion and removal of said resistance and, upon said power reaching a predetermined value, to coperate with said automatic means to disconnect the rotary transformer from the supply circuit and from the distribution circuit.

22. The combination with an alternating current circuit and aV direct current circuit, one ofsaid vcircuits beingl a supply circuit and the other a distribution circuit, of a rotary transformer provided With a shunt field winding and a series field winding and Vadapted to be electrically connected therebetween, and automatic means operable upon a decrease in the voltage of the distribution circuit'to start said rotary transformer. from the supply circuit, then to connect said shunt field winding across the distribution circuit and subsequently to connect said rotary transformer to the distribution circuit to supply power there-to.

In witness whereof, I have hereunto set my hand this second day of July, 1915.

v EDWARD TAYLOR.

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