US1501699A - System of electric distribution - Google Patents

Description

July 15, 1924.

E. F. BLISS SYSTEM OF ELECTRIC DISTRIBUTION Filed Aug. 1. 1923 [five/76 or: f Awe/"F 67/198.

Ms/qttorney Patented July 15, 1924.

UNITED STATES 1,501,699 PATENT OFFICE.

ELMER F. BLISS, OF ALPLAUS, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COM- PANY, A CORPORATION OF NEW YORK.

SYSTEM 013 ELECTRIC DISTRIBUTION.

Application filed August 1, 1923. Serial No. 655,114.

To all '11: am it may concern:

Be it known that I, ELMER F. Buss, a citizen of the United States, residing at Alplaus, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Systems of Electric Distribution, of which the following is a specification.

My invention relates to systems of electric distribution, and particularly to such systems in which it is very essential that the supply of current thereto should not be interrupted any longer than is absolutely necessary, and an object of my invention is to provide an improved arrangement for connecting. another source of current to an electric circuit when the main source fails and for disconnecting the auxiliary source of current when the main source is again connected to the circuit.

My invention is especially adapted for use in a railway signalingsystem which usually comprises a supply circuit extending along the railway system. In very long railway systems this circuit is usually divided into sections in order to reduce the line losses and each section is normally energized by an independent source of current. When, however, any one of the normally connected sources fails, it is desirable to connect one end of the deenergized section to the adjacent end of an energized section so that the source normally connected thereto may supply current to both sections until the deenergized section is again supplied by its normal source.

In accordance with my invention I provide a circuit breaker between the adjacent ends of two sections of such a system and control the closing of this circuit breaker in accordance with the voltages of the two sections and control the opening of the circuit breaker in accordance with the current flowing from one section to the other when the circuit breaker is closed. Since the sections of a railway signaling system are usually arranged so that the loads connected to all of the sections are substantially equal, substantially no current flows from one section to the other when the circuit breaker between them is closed and both sections are energized by their normal sources. When, however, only one of the sections is energized by its normal source, all of the current supplied to the adjacent section flows through the circuit breaker. Therefore, the amount of current flowing from one section to the other is an indication as to whether or not both sections are being supplied by their respective sources and may be used to control the operation of the circuit breaker connecting the two sections.

In its broadest aspects, however, my invention is not limited to signaling systems but relates to any system com rising two electric circuits which normal y are independently energized and which are arranged to be connected together whenever the source connected to either circuit fails and to be disconnected from each other when the circuits are independently energized.

My invention will be better understood from the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims.

. In the accompanying drawing, Fig. 1 shows diagrammatically a system of electric distribution to which my invention is particularly applicable; Fig. 2 shows diagrammatically one embodiment of my invention; and Fig. 3 shows diagrammatically a modification of the embodiment of my invention shown in Fig. 2.

In Fig. l in which I have shown an alternating current system of electric distribution for which my invention is particularly adapted, the system comprises two sections 1 and 2, which are normally disconnected from each other, and which are independently energized by separate sources. As shown the section 1 is connected to a generator 3 by means of a circuit breaker 4 and the section 2 is connected to a generator 5 by means of a circuit breaker 6. \Vhile I have shown separate generators for each section it is apparent that it is immaterial whether separate generators or separate feeders supplied from the same generator are used. A circuit breaker 7 is provided between the adjacent ends of the two sections 1 and 2 so that they may be connected together. The distributed load on each section is indicated by the transformers 8.

As long as both of the sources are independently energized it is desirable to keep the two sections disconnected from each other. W hen, however, either source fails it is desirable to connect both sections together so that both will be-energized from the same source, and to disconnect the two sections from each other as soon as both sections are again independently energized.

Fig. 2 shows one embodiment of my invention for accomplishing this result. The circuit breaker 7 between the two sections is provided with a closing coil 14 which is arranged to be energized whenever the voltage across either section decreases below a predetermined value. The voltage of each circuit is determined .by the voltage relays 10 and 11 which are respectively connected to the circuits 1 and 2 by the potential transformers 12 and 13. Whenever either one of these relays is deenergized, a circuit is completed for the closing coil 14 of the circuit breaker to close the circuit breaker 7. In order to prevent the circuit of the closing coil 14 from being opened when the voltage relay across the deenergized section is again energized by the closing of the circuit breaker 7, a circuit for the closing coil 14 is completed by a current relay 15 which is connected, by means of the current transformer 16, so as to respond to the current flowing through the circuit breaker. In order that the circuit for the closing coil 14 through the contacts of the current relay 15 may be closed before the circuit of the closing coil 14, through the contacts of either one of the voltage relays is opened after the closing of the circuit breaker, it is preferable to design the voltage relays 10 and 11 in any suitable manner so that the opening of their respective contacts is delayed until after the coils of the respective relays have been energized a predetermined length of time.

As long as the current flowing from one section to the other is above a predetermined value the current relay 15 maintains the circuit of the closing coil 14 closed. When, however, the current decreases below a predetermined value the current relay 15 opens its contacts and deenergizes the closing coil 14 so that the circuit breaker 7 opens and disconnects the two sections from each other. In order that the circuit breaker may not be opened in response to a momentary decrease in the current, the relay '15 is preferably designed so that it does not open its contacts until after the current through the coil of the relay has remained below a predetermined value for a predetermined length of time.

In case a short circuit or an overload is connected to one of the sections when the circuit breaker is closed the circuit breaker should be opened. For accomplishing this result an overload relay 20 is connected to the current transformer 16 and is arranged to open the circuit of the closing coil 14 of the circuit breaker when the current flowing from one section to the other, exceeds a predetermined value.

In order that the circuit breaker may be automatically reclosed a predetermined number of times before the circuit breaker is permanently opened when there is 'a short circuit or an'overload connected to the deenergized section, the overload relay 20 is arranged to reclose its contacts a predetermined time after its coil is deenergized by the opening of the circuit breaker, and

thereby complete the circuit of the closing coil 14 to reclose the circuit breaker. A notching relay 22, having a coil 23 which is arranged to be energized each time the closing coil 14 is energized, is provided to open the contacts 24 in the circuit of the closing coil 14 if the closing coil is enerized a predetermined number of times. The contacts 24 after being opened by the notching relay remain in their open position until they are closed by hand. As shown, the notching relay 22 is of the well known automatically reset ty e which is arranged to return to its initIal position if more than a certain length of time elapses between successive energiza-tions of the operating coil 23.

The operation of the arrangement shown in Fig. 2 is as follows: When the circuit breaker 7 is open and both sections are independently energized the relays 10 and 11 are energized and the circuit of the closin coil 14 is open. When the source connecte to either one of the sections fails and. the voltage across the section decreases below a predetermined value, the voltage relay connected across this section closes its lower contacts.

Let it be assumed that the source connected across section 1 fails so that the voltage relay 1O closes its contacts 21. A circuit is then completed from the ungrounded terminal of the secondary winding of the potential transformer 13, c0nductor 25, contacts 21 of the voltage relay 10, conductor 26, contacts 27 of the volta e relay 11, conductor 28, contacts 29 of t e overload relay 20, conductor 30, closing coil 14 of the circuit breaker 7 and coil 23 of the notching relay 22 in parallel, conductor 31, contacts 24 of the notching relay 22 to the grounded terminal of the secondary winding of the potential transformer 13. In response to the energization of the coil, 23, the notching relay 22 notches up one step but does not open its contacts 24.

The closing of the circuit breaker 7 causes current to flow from section 2 to section 1 and this current causesthe current relay 15 to close its contacts 32. A circuit is then completed from the ungrounded terminal of the secondary winding of the potential transformer 13, conductor 25, contacts 32 of the current relay 15, conductor 28, contacts 29 of the overload relay 20, conductor 30, coils 14 and 23 in parallel, conductor 81, contacts 24 of the notching relay 22 to the 32 of the current relay 15 closed. When,

however, the section 1 is again independently energized, and the source connected thereto assumes its share of the load, the

current which flows from section 2 to section 1 is not sufiicient to maintain the current relay 15 in its operated osition. After a predetermined time the re ay 15 opens its contacts 32 thereby 'deenergizing the coils 14 and 23 so that the circuitbreaker7 is opened and the notching relay 22 is restored to its initial position. a

In case there is a short circuit or an overload connected to the section 1 when the circuit breaker 7 is closed, the overload relay 20 opens its contacts 29 as soon as the circuit breaker 7 is closed, thereby efiecting the opening of the circuit breaker and the decnergization of the coil 23 of the notching relay. After a predetermined time the overload relay 20 closes its contacts 29 and thereby completes the heretofore described energizing circuits of the closing coil 14 and the coil 23 of the notching relay 22. If the short circuit or overload is still connected to the section 1 when the circuit breaker is reclosed, the overload relay 20 again operates and the above cycle of operation is repeated. If the short circuit or overload remains connected to the section for a sufiicient length of time so that the notching rela 22 is actuated a predetermined number 0 times, this relay opens the contacts 24 in the circuit of the closing coil 14 so that the circuit breaker remains open until the contacts 24 are again closed by hand.

It is evident that the operation is the same as above described when the source normally connected to section 2 fails except that the energizing circuit of the closing coil 14 is from the ungrounded terminal of the secondary winding of thepotential transformer 12, conductor 35, contacts 21 of the relay 11, conductor 36, contacts 37 of the voltage relay 10, conductor 28, contacts 29 of the overload relay 20, conductor 30, closing coil 14, conductor 31, contact 241 of the notching relay 22, to the grounded terminal of the secondary winding of the potential transformer 12. After the current relay l5 closes its contacts 32 the closing coil 14 is energized from the potential transformer 13 in the manner above described.

In the modification of my invention shown 7 in Fig. 3 I have shown my invention ap-. plied to a three-phase system instead of a single phase system as shown in Fig. 2. The voltage relay 10 is replaced by the three vol relays, 10, 10, and 10 which are connec across the different phases of section 1 by the transformers 12, 12 and 12 respective] The voltage relay 11 is replaced by the t ree voltage relays 11, 11" and 11 which are connected across the different phases of section 2. by the transformers 13,

13" and 13. The current relay 15 is replaced by the current relays 15, 15" and 15 which are connected by means of the transformers 16, 16 and 16 respectively to the different "phases of the section 1. The overload relay 20 is replaced by the overload relays 20, 20 and 20, which are respective- I 1y connected .to the current transformer 16, 16 and 16.

It will be observed that since the contacts 21 of the voltage relays 10 and 11 are replaced respectively b the serially connected contacts 21, 21 an 21 of the relays 10, 10" and 10 and the serially connected contacts 21, 21 and 21 of relays 11, 11 (1 11, and contact 37 of relay 10 is replaced the serially connected contacts 37", 37 an 37 of the relays 10', 10 and 10, and contact 27 of relay 11 is replaced by the serially connected contacts 27', 27" and 27 of relays 11, 11 and 11, the voltages of all of the hases of one section must be below reetermined values and the voltages of a of the phases of the other section must be above predetermined values before the circuit breaker 7 can close. Furthermore, since the contacts 29 of the overload relay 20 is replaced by the serially connected contacts 29, 29", and 29 of the overload relays 20', 20" and 20, and the contact 32 of the current relay 15 is replaced by the serially connected contacts 32, 32" and 32 of the relays 15, 15 and 15, it is evident that either a current above a predetermined value or a current below a predetermined value in any one phase opens the circuit breaker 7 when it is closed. I

In 1polyghase systems of distribution it is usual y t e practice to provide suitable means for disconnecting a source from the system when a predetermined unbalancing of the phases occurs. In order to prevent the circuit breaker 7 from being reclosed when either one of the sections is completel deenergized after a predetermined unba ancing of the phases occurs, the relays 50 and 51, which may be of any suitable type, are connected to the sections 1 and 2 respectively and are provided with the contacts 52 and 53 which are connected in the circuits of the closing coil 14 of the circuit breaker and the coil 23 of .the notching relay. These contacts, which have to be reset manually, are arranged to be opened when there is a predetermined unbalancing of the phases on the section to which the associated relay is connected, so that the circuit breaker cannot be automatically closed after the occurrence of such a condition. In this way an unbalanced phase condition on one section, which causes said section to be deenergized, is prevented from unbalancing the phases on an adjacent energized section, and thereby cause said adjacent section to be deenergized. v

The contacts of the various devices shown in Fig. 3 are connected in the same manner as the corresponding devices shown in Fig. 2, and therefore it is believed the operation of'the modification will be obvious from the description given above in connection with Fig. 2.

While I have shown and described several modifications of my invention, I do not desire to be limited thereto but seek to cover in the appended claims all those modifications that fall within the true spirit and scope of my invention.

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

1. In a system of distribution, two electric circuits normally disconnected from each other, means for energizing each circuit, means responsive to the deenergization of either one of said circuits while the other circuit is energized for connecting both circuits together, and means adapted to effect the disconnection of said circuits from each other when the current supplied from one circuit to the other circuit when they are connected together decreases below a predetermined value.

2. In a system of distribution, two electric circuits normally disconnected from each other, means for energizing each circuit, electroresponsive means adapted to connect said circuits together, voltage responsive means adapted to efi'ect the energization of said electroresponsive means when the voltage of either one of said circuits decreases below a predetermined value, and means re sponsive to the current supplied from one circuit to the other when they are connected together for effecting the deenergization of said el'ectroresponsive means when said current is below predetermined value.

3. In a system of distribution, two electric circuits normally disconnected from each other, means for energizing each circuit, a circuit breaker arranged to connect said circuits together, a closing coil for said circuit breaker, voltage responsive means connected to each circuit and adapted to complete a circuit for said closing coil when the voltage of the circuit to which the re spective means is connected decreases below a predetermined value, means responsive to the current flowing between said circuits when said circuit breaker is closed for maintaining said closing coil energized so long as the current does not increase above or decrease below predetermined values, and means for limiting the number of times said circuit may be reclosed.

4. In an alternating current system of dis tribution, two polyphase circuits normally disconnected from each other, a source of polyphase current adapted to be connected to each circuit, a circuit breaker adapted to connect said circuits together, means adapt ed to effect the closing of said circuit breaker when the voltage of all of the phases of either one of said circuits decrease below predetermined values, and means responsive to the current flowing from one circuit to the other circuit when said circuit breaker is closed for efiecting the opening of said circuit breaker when the current in any one phase decreases below a predetermined value.

5. In an alternating current system of distribution, two polyphase circuits normally disconnected from each other, a source of polyphase current adapted to be connected to each circuit, a circuit breaker adapted to connect said circuits together, means adapted to efiect the closing of said circuit breaker when the voltages of all of the phases of either one of said circuits decrease below predetermined values, means responsive to the current flow between said circuits when said circuit breaker is closed for controlling the opening of said circuit breaker, and a lockout relay responsive to a predetermined unbalancing of the phases of one of said circuits for preventing the closing of said circuit breaker.

6. In an alternating current system of distribution, two polyphase circuits normally disconnected from each other, a source of polyphase current adapted to be connected to each circuit, a circuit breaker adapted to connect said circuits together, means adapted to eiiect the closing of said circuit breaker when the voltages of all of the phases of one of said circuits decrease below predetermined values, and the voltages of all of the phases of the other circuit are above predetermined values, means responsive to the current flowing between said circuits when said circuit breaker is closed for effecting the opening of said circuit breaker when the current in any phase increases above or decreases below a predetermined value, and a lookout relay responsive to a predetermined unbalancing of the phases of

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