JPH04245816A - Feeder switching circuit - Google Patents

Abstract

PURPOSE:To continue communication between the other faultless terminal stations even at the time of generating fault at one optional terminal station by adding one switching relay to a feeder switching circuit. CONSTITUTION:A first and a second relays R1, R2 operate at the time of feeding to both-terminal by two terminal stations among a first, a second, and a third terminal stations A, B, C. A third and a fourth relays R3, R4 are provided with self holding make contacts r32, r42 to operate at the time of feeding to single-terminal between the second and the third terminal stations and the earth. The switching relay R5 is connected to operate at the time of feeding to the both-terminal at the time of the feed is switched to the single-terminal feed after the both-terminal feed from the second and the third terminal stations B, C is executed at the time of generating the fault between the first terminal station A and a branching device, and connect the first and the second relays R1, R2 to a second and a third terminal station B, C sides by the make contacts r51, r52 of the switching relay R5.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply line switching circuit for switching a power supply line to a repeater between three terminal stations and a branching device. In long-distance optical transmission systems such as optical submarine cable systems, optical repeaters are provided for amplifying and repeating optical signals every about 100 km or so. This type of optical repeater connected in series between terminal stations is supplied with power by constant current control from the power supply device of the terminal station, and is a single-ended power supply method in which power is supplied only from the power supply device of one terminal station. There is a two-end power feeding method, in which power is supplied from power feeding devices at both terminal stations, and the two-end power feeding method is adopted in long-distance optical transmission systems due to the relationship between power supply voltage and power. Also, an optical transmission system is known in which three terminal stations are connected via a branching device, and the branching device switches the optical transmission line as well as the power supply line, so that any terminal station of the branching device can It is desired to be able to continue communication between two other terminal stations even if there is a failure between two terminal stations.

0002

[Prior Art] FIG. 6 shows a conventional power supply line switching circuit.
A, B, and C indicate terminal stations, and repeaters and switching configurations of optical transmission lines are not shown. Also, R1, R2, R3, R4 are relays, r11, r21, r31, r41 are relays R1,
Break contacts of R2, R3, R4, r12, r22, r
32 and r42 are make contacts of relays R1, R2, R3, and R4. Each of the relays R1 to R4 is a high-voltage vacuum relay and has two contacts.

For example, power is supplied at both ends between terminals A and B, and terminal C
When supplying power at one end between the terminal A and ground, as shown in the diagram, first set terminal A to positive polarity and terminal B to negative polarity, and apply a power supply voltage from each power supply device that will provide the operating current of the relay. Supply power. Thereby, break contacts r21, r
A current flows through relay R1 through 41 to operate it. Next, the terminal station C is set to negative polarity, and a power supply voltage that becomes the operating current of the relay is supplied from the power supply device. As a result, current flows through the relay R3 between the terminal station C and the ground via the make contact r12 (on) of the relay R1, and the relay R3 operates. Then, when the power supply voltage of terminal stations A, B, and C is increased to a predetermined value, relay R1 is installed in the repeater between terminal stations A and B.
A current due to both-end power supply flows through the relay R3, and a current due to single-end power supply flows through the relay between the terminal station C and the branch device.

[0004] Also, when supplying power at both ends between terminal stations A and C, and supplying power at one end between terminal station B and ground, in the illustrated state, terminal station A is set to positive polarity and terminal station C is set to negative polarity. Power is supplied from each power supply device with a power supply voltage that provides an operating current of . As a result, current flows through the break contacts r11 and r31 to the relay R2, causing it to operate. Next, when terminal station B is set to negative polarity and a power supply voltage that is the operating current of the relay is supplied from the power supply device, relay R between terminal station B and ground is
4, current flows through make contact r22 (on) of relay R2, and relay R4 operates. And terminal station A,
When the power supply voltages of B and C are increased to a predetermined value, terminal stations A,
A current due to both-end power supply flows through the relay between terminal station B and the branching device via relay R2, and a current through one-end power supply flows through the relay between terminal station B and the branch device via relay R4.

[0005]

In the conventional example shown in FIG. 6, it is possible to switch between power feeding at both ends between terminal stations A and B and power feeding at both ends between terminal stations A and C. However, if power cannot be supplied at both ends due to a failure in terminal A or a failure between terminal A and the branching device, power can be supplied at both ends between terminal stations B and C, or by single-end power supply between terminal stations B and C. , there was a drawback that communication between terminal stations B and C could not be continued. That is, in a state where power is being supplied at both ends between terminals A and B,
When power supply at both ends is stopped due to a failure on the terminal station A side, relay R1 is restored, and relay R3 is self-held by make contact r32, and one-end power supply by terminal station C is continued, but relay R4 is not activated. Since terminal B cannot
It is not possible to perform one-sided power supply. Therefore, since power cannot be supplied to the repeater between terminal station B and the branching device, communication between terminal stations B and C cannot be continued.

[0006] Also, as mentioned above, relays R1 to R4 are 2
It is practically impossible to increase the number of contacts in the relay because it is composed of a vacuum relay having several contacts. It is also possible to realize various switching circuit configurations by increasing the number of relays, but when applied to submarine branching equipment in submarine cable systems, miniaturization is required, so relays are There are also restrictions on increasing the number. An object of the present invention is to switch to an arbitrary power supply path without adding one relay or adding any relays.

[0007]

[Means for Solving the Problems] The power supply line switching circuit of the present invention switches to an arbitrary power supply line by providing a switching relay, and will be described with reference to FIG. The first invention provides a power supply line switching circuit that switches a power supply line that supplies power to a repeater between a first, second, and third terminal station and a branching device.
The first and second relays R1 and R2 operate when power is supplied to both ends by two terminal stations among the first, second and third terminal stations, and one end between the second and third terminal stations and the ground. It includes third and fourth relays R3 and R4 having self-holding make contacts r32 and r42 that operate when power is supplied, and a switching relay R5, and this switching relay R5 connects the first terminal station and the branching device. Connected so as to operate during both-end power supply when switching to single-end power supply after performing both-end power supply from the second and third terminal stations in the event of a failure between the terminals,
The make contacts r51 and r52 of this switching relay R5 connect the first and second relays R1 and R2 to the second and third terminal stations.

[0008] Also, the second invention provides break contacts r21 of second and fourth relays R2 and R4 in series with the first relay R1.
, r41, and these break contacts r21, r4
Connect the make contact r51 of switching relay R5 in parallel to 1, and connect the first and third relays R1 and R in series to the second relay R2.
The break contacts r11 and r31 of the switch relay R5 are connected in parallel to these break contacts r11 and r41, and the first terminal of the parallel connection is connected between the second terminal station and the ground. The third relay R is connected to the third relay R via the make contact r12 of the relay R1 and the make contact r32 for self-holding.
3 is connected, and a fourth relay R4 is connected between the third terminal station and the ground via the make contact r22 of the second relay R2 connected in parallel and the make contact r42 for self-holding,
It has a configuration in which a diode D1 is connected in series to a switching relay R5.

The third invention further has a configuration in which a series circuit of a switching relay R5 and a diode D1, and a series circuit of a diode of opposite polarity to this diode D1 and a second relay R2 are connected in parallel. It is.

[0010] Also, the fourth invention includes first, second, and third relays R1, R2, and R3 and a switching relay R5, and a switch is provided between the first terminal station and the second terminal station. The first relay R1 and the break contact r21 of the second relay R2 are connected in series, and the second relay and the first relay are connected between the first terminal station and the third terminal station.
, break contacts r11, r3 of third relays R1, R3
1 and a diode are connected in series, and a second relay R2
A series circuit consisting of a diode and a diode, and a series circuit consisting of a diode with a polarity opposite to this diode and switching relay R5 are connected in parallel, and a third relay R is connected between the third terminal station and ground.
3 and the make contact r12 of the first relay R1 are connected in series, and the self-holding make contact r32 of the third relay R3 is connected in parallel with the make contact r12, and the second
The make contact r51 of the switching relay R5 was connected in parallel to the break contact r21 of the relay R2, and the make contact r52 of the switching relay R5 was connected in parallel to the break contacts r11 and r31 of the first and third relays R1 and R3. It has a structure.

[0011] The fifth invention is further configured such that a make contact r22 of a second relay R2 is connected between the second terminal station and the ground.

0012

[Operation] The first invention provides first and third relays R1 and R3.
By operating the first and second terminal stations (A, B)
Power is supplied at both ends between the terminal station (C) and earth (E), and power is supplied at one end between the third terminal station (C) and the ground (E), and the second and fourth relays R2 and R4
By operating the first and third terminal stations (A, C)
It is possible to switch so that power is supplied at both ends between the terminal station (B) and the ground (E), and power is supplied at one end between the second terminal station (B) and the ground (E).

[0013] Furthermore, in the event of a failure between the first terminal station and the branch device, the first relay R1 is restored and the third relay R3 continues to operate due to the self-holding make contact r32 (on). There is. Therefore, after stopping the power supply to the third terminal station and putting all relays R1 to R5 into the recovery state, the third terminal station is set to positive polarity and the second terminal station is set to negative polarity, and switching relay R5 is switched on. An operating current is applied to turn on the make contacts r51 and r52. Note that at the operating current at this point, the first and second relays R
1. Prevent R2 from operating. Next, the power supply current between the second and third terminal stations is increased to operate the first relay R1. As a result, the make contact r12 is turned on and the break contact r11 is turned off.

Next, power supply to the third terminal station is stopped. Therefore, power will be supplied only from the second terminal station, and if only the symbols are shown, B→r51→R1→R5→D1→r52→r
On the path 12→R3→E, the second terminal station becomes in a state of single-end power feeding. As a result, the third relay R3 operates, the break contact r31 turns off, the make contact r32 turns on, and the third relay R3 turns off.
Relay R3 enters a self-holding state. Next, while keeping the power supply current to the second terminal station constant, power is supplied to the third terminal station with negative polarity. The power supply current is increased so that the third relay R3 can continue to operate with only the power supply current of this third terminal station. Also, the power supply current to the second terminal station is further increased. As a result, the second relay R2 connected in parallel to the fifth relay R5 is activated, and the break contact r21 is turned off and the make contact r22 is turned on.

[0015] Therefore, if only the signs are used, B→r22→
On the path R4→E, the second terminal shifts to one-end power supply, and the fourth relay R4 operates, its break contact r41 turns off and its make contact r42 turns on, resulting in a self-holding state. Next, the power supply currents of the second and third terminal stations are increased to normal values. That is, it is possible to continue communication between the second and third terminal stations by switching to one-end power feeding between the second and third terminal stations and the ground. In addition, the switching relay 5 has two contacts r51,
This is a normal vacuum relay equipped with 52, and by simply adding one relay, even if any terminal station fails, a power supply path can be formed between two other terminal stations to continue communication. Can be done.

[0016] In addition, the second invention connects a diode D1 in series with the switching relay R5, so that when the first terminal side fails, the second terminal
, When starting up power supply to the third terminal station, when the second terminal station is set to negative polarity and the third terminal station is set to positive polarity, switching relay R is activated.
5 is made to operate, and when power is supplied at both ends between the first and second terminal stations, and when power is supplied at one end between the third terminal station and the ground, a failure occurs on the first terminal side. In this case, as in the case described above, stop the power supply to the third terminal station, restore all relays, and then set the third terminal station to positive polarity and the second terminal station to negative polarity. The switching relay R5 is operated, the power supply current is increased to operate the first relay R1, and then the power supply to the third terminal station is stopped. At that time, if we show only the sign, B→r
51 -> R1 -> R5 -> D1 -> r52 -> r12 -> R3 -> E transitions to one-end power supply, and the third relay R3 operates. Next, power supply is started with the third terminal station set to negative polarity, and the second
The power supply current of the terminal station is also increased to operate the second relay R2. As a result, the path B→r22→R4→E shifts to one-end power feeding, is self-maintained by the operation of the fourth relay R4, and increases the power feeding current between the second and third terminal stations to a normal value. This results in one-end power feeding between the second and third terminal stations and the ground.

[0017] Furthermore, the third invention is such that a diode is connected in series to the second relay R2, and the second relay is
, when starting up power supply between the third terminal station, the third terminal station is set to positive polarity, the second terminal station is set to negative polarity, and switching relay R5 is activated.
After operating the first relay R1, the power supply current is increased to operate the first relay R1. At that time, the diode connected in series to the second relay R2 becomes reverse biased, so
The second relay R2 does not operate. Then, power supply to the third terminal station is stopped. At that time, B→r51→R1→R5→D
1→r52→r12→R3→E transitions to one-end power supply, and the third relay R3 operates. Next, when the third terminal station is set to negative polarity and the feeding current is increased, the first, third, and fifth relays R1, R3, and R5 are activated, so that the second and third terminal stations A one-end power supply state is established in which current flows between the ground and the third relay R3.

[0018] The fourth invention also provides four relays R1 and R2.
, R3, and R5, and the second terminal station is assumed to perform power supply only at both ends between it and the first terminal station.
, when performing both-end power supply between the second terminal station and single-end power supply between the third terminal station and the ground, the first and third relays R1 and R
3 works. Further, when a failure occurs on the second terminal side, the second relay R2 is operated to switch so that power is supplied to both ends between the first and second terminal stations. In addition, in the event of a failure on the first terminal side, the first relay R1, switching relay R5, and third relay R3 operate due to the operation at the time of starting up the power supply between the second and third terminal stations described above, B→r51→R1→R5→D1→
A current flows between the second terminal station B and earth E on the path r52 → r12 → R3 → E, and a current flows between the third terminal station C and earth E on the path E → r32 → C. flows, so the second
, the third terminal station and the ground are in a state of one-end power supply in which current flows through the third relay R3.

[0019] Furthermore, a fifth invention, in contrast to the fourth invention, is such that the make contact r22 of the second relay R2 is connected between the second terminal station and the ground, and the make contact r22 of the second relay R2 is When carrying out both-end power supply between the terminal stations of No. 3, the second relay R2 operates, so a path for the supply current is formed between the second terminal station and the ground via its make contact r22, and the second relay R2 operates. This enables single-end power feeding between the second terminal station and the ground. In addition, in the state where power is being supplied at both ends between the first terminal station and the second or third terminal station, due to the occurrence of a fault on the first terminal station side, the state where power is being supplied at both ends between the second and third terminal stations is interrupted. Then, after operating the switching relay R5 and the first and third relays R1 and R3, if the feeding polarity of the third terminal station is reversed, the connection between the third terminal station and the ground becomes C→
The feeding current flows through the path r32→R3→E, and between the second terminal station and the ground is B→r51→R1→R5→D1→
The power supply current flows through the path r52→r12→R3→E,
A third relay R3 is connected between the second and third terminal stations and the ground.
A state of single-ended power supply is established in which current flows through the terminal.

[0020]

[Embodiment] FIG. 1 is an explanatory diagram of a first embodiment of the present invention, in which the same reference numerals as in the conventional example shown in FIG. 6 indicate the same parts, and R5
is a switching relay, r51 and r52 are make contacts, D1 is a diode, and repeaters between the first, second, and third terminal stations A, B, and C and the branch device are not shown. . In this embodiment, the make contact r51 of the switching relay R5
are connected in parallel with break contacts r21 and r41, and make contact r52 is connected in parallel with break contacts r11 and r31, respectively, and a series circuit of diode D1 and switching relay R5 is connected in parallel with second relay R2. There is.

[0021] Both-end power feeding between terminal stations A and B, one-end power feeding between terminal station C and earth E, both-end power feeding between terminal stations A and C, and one-end power feeding between terminal station B and earth E are as follows. The operation is similar to the conventional example. Also, both ends power supply between terminal station A and B, terminal station C and earth E
If a failure occurs on the terminal station C side in the state of single-end power supply between
Since terminal station 1 continues to operate, power feeding between both terminals A and B continues. If a failure occurs on the side of terminal station B, the power supply to terminal station C is temporarily stopped, each relay R1 to R5 is set to the initial state shown in Fig. 1, and then the power supply at both ends is switched between terminal stations A and C. In this state, the second relay R2 operates, and the terminal B side is grounded via the make contact r22 and the fourth relay R4. In addition, when power is being supplied at both ends between terminal stations A and C, and power is being supplied at one end between terminal station B and earth E, if a failure occurs on the terminal station B side, power supply at both ends between terminal stations A and C is continued. , when there is a failure on the terminal C side,
The power supply is switched to both ends between terminal stations A and B.

[0022] In addition, when a fault occurs on the terminal A side in both-end power supply between terminal stations A and B and one-end power supply between terminal station C and earth E, the power supply to terminal stations B and C is temporarily stopped. The relays R1 to R5 are brought to the initial state shown in FIG. 1. Then, with terminal station C as positive polarity and terminal station B as negative polarity, first relay R1
For example, a switching relay R5 with an operating current of several hundred mA or less
The operating current is supplied with power supplied to both ends. That is, the switching relay R5 is configured to have an operating current smaller than that of the first and second relays R1 and R2, and the operating currents of the first and second relays R1 and R2 are approximately equal. It is. Next, increase the power supply current to the first relay R1.
make it work. At this time, since the switching relay R5 is connected in parallel, the second relay R2 is connected to the first relay R1.
When it operates, only a current lower than the operating current flows, so it does not operate yet. Furthermore, the terminal stations A, B, and C are connected to the ground E via the make contact r12 of the first relay R1 and the third relay R3.

Next, power supply to terminal station C is stopped, and power is supplied only to terminal station B (negative polarity). Therefore, B→r51→R1→R
5→D1→r52→r12→R3→E transition to single-end power feeding. Relay R3 is operated by this power supply current from terminal station B (negative polarity), make contact r32 is turned on, break contact r31 is turned off, and relay R3 is self-held. Next, terminal station C is set to negative polarity and power supply is started. and,
The third relay R3 is made to operate with only the power supply current from the terminal station C, and the power supply current from the terminal station B is also increased. Due to this increase in the power supply current of terminal B, switching relay R
When the current flowing through the second relay R2 connected in parallel with 5 also increases and becomes equal to or higher than its operating current, the second relay R2
2 works. As a result, break contact r21 turns off,
Make contact r22 turns on, the power supply current of terminal B (negative polarity) flows through the path B → r22 → R4 → E, the fourth relay R4 operates, break contact r41 turns off, make contact r42 turns on, and the relay R4 is self-retaining.

Therefore, as shown in FIG. 2, the current stops flowing through the first and second relays R1 and R2 and the switching relay R5, so that the state is restored and only the third and fourth relays R3 and R4 operate. As a result, make contacts r51 and r52 turn off, break contacts r41 and r31 turn off, and terminal station A where the fault occurs.
The side is separated from the terminal stations B and C sides. And terminal stations B and C
(Negative polarity) and earth E, as shown by the arrow, supplies power to a repeater (not shown) between terminal stations B and C.
Communication between terminal stations B and C becomes possible.

[0025] Also, in the event of a failure on the terminal A side in both-end power supply between terminal stations A and C and one-end power supply between terminal station B and earth E, the terminal is One-end power feeding between stations B and C and earth E enables communication between terminal stations B and C. Moreover, the switching relay R5 is connected to the other relays R1 to R.
Like 4, it is a vacuum relay with two contacts, and by simply adding one relay, it is possible to switch to one-end power supply between terminals B and C and the ground in the event of a failure on the terminal A side. can.

FIG. 3 is an explanatory diagram of a second embodiment of the present invention, in which the same reference numerals as in FIG. 1 indicate the same parts, and D2 is a diode. This diode D2 is connected in series to the second relay R2 with the opposite polarity to the diode D1 connected in series with the switching relay R5, and is connected in series to the second relay R2 due to a failure on the terminal station A side.
It is configured such that it does not operate in a dual-end power supply state in which terminal station C has positive polarity and terminal station B has negative polarity when one-end power supply is started by C. In addition, when power is supplied at both ends between terminal stations A and B, and when power is supplied at one end between terminal station C and earth E, the first and third relays R1 and R3 operate, and the power supply between terminal stations A and C is activated. When power is being fed at both ends of the terminal B and ground E is being fed at one end, the second and fourth relays R2 and R4 operate.

[0027] Also, if a fault occurs on the terminal A side during both-end power supply between terminal stations A and B, and one-end power supply between terminal station C and earth E, the operation is the same as that described with respect to Figs. 1 and 2. It is possible to start up the one-end power supply between terminal stations B and C and earth E using the following procedure, but at that time, the power supply between terminal station B (negative polarity) and terminal station C (positive polarity) Even if the power supply current is increased to operate the first relay R1 and the power supply current is further increased, the second relay R1 is activated.
Relay R2 does not operate because diode D2 becomes reverse biased. Therefore, after operating switching relay R5, operating first relay R1, stopping power supply to terminal station C and operating third relay R3, and then supplying power to terminal station C with negative polarity. , the power supply currents of terminal stations B and C are set to normal values,
For example, when the voltage is increased to 1.6A, the first and third relays R1 and R3 and the switching relay R5 operate, and the second and fourth relays operate.
Since relays R2 and R4 have been restored, B→r51→
The power supply current of terminal B (negative polarity) flows through the path R1 → R5 → D1 → r52 → r32 → R3 → E, and C → r32 → R3
→The power supply current of terminal station C (negative polarity) flows through the path E, and one-end power supply is performed between terminal stations B, C and earth E. Therefore, power is supplied to the repeater between the terminal stations B and C, and communication between the terminal stations B and C can be continued.

FIG. 4 is an explanatory diagram of a third embodiment of the present invention, in which the fourth relay R4 and its make contacts r41 and r42 in the second embodiment are omitted, and the second relay R2 is omitted. A case is shown in which the terminal station B is connected to the earth E via the make contact r22, and corresponds to the fifth invention described above. In this embodiment, power is normally supplied at both ends between terminal stations A and B, and one end is supplied between terminal station C and earth E, and only in the event of a failure on the terminal station B side, power is supplied at both ends between terminal stations A and C. It is set to switch. Therefore, the fourth relay R4, which self-maintains the one-end power supply state between the terminal station B and the ground, and its make contact r42 are omitted.

In addition, when a failure occurs on the side of terminal A, as in the previous embodiment, the power supply to terminals B and C is temporarily stopped, each relay is set to the initial state, and then terminal C is set to the positive polarity, and the terminal Switching relay R5 is operated in the state of both ends feeding with B as negative polarity, then the feeding current is increased to operate the first relay R1, and then, after temporarily stopping the feeding of terminal C, the feeding polarity is changed. Invert. Thereby, similarly to the second embodiment, the third relay R
The power supply is switched to one-end power feeding between the terminal station C and the earth E and between the terminal station B and the earth E through the terminal C and the earth E. Therefore, in the event of a failure on the terminal station A side, it is possible to switch to one-end power feeding between the terminal stations B and C and the ground using four relays, as in the conventional example.

FIG. 5 is an explanatory diagram of a fourth embodiment of the present invention, in which the make contact r22 of the second relay R2 in the third embodiment is omitted; This corresponds to the invention of Normally, power is supplied at both ends between terminal stations A and B (first relay R1 operates), and power is supplied at one end between terminal station C and ground (
3rd relay R3 operation), and due to a failure in terminal station B, it switches to both-end power feeding between terminal stations A and C (second relay operation).

In the case of a failure on the side of terminal station A, one-end power supply to terminal stations B and C is started up using the same procedure as in each of the above-described embodiments. That is, terminal station B is set to negative polarity and terminal station C is set to positive polarity, and the switching relay R5 is operated in a both-end power supply state, and then the supply current is increased to operate the first relay R1, and thereby the third relay After operating R3 and temporarily stopping power supply to terminal C, set the supply polarity to negative polarity and connect terminals B and C.
By increasing the power supply current to the normal value, for example, 1.6A, the first and third relays R1 and R3 and the switching relay R5 are activated, and the second and fourth relays R2 are restored. From, B→r51→R1→R5→D1→r52→r3
The power supply current of terminal station B (negative polarity) flows through the path 2→R3→E, and the power supply current of terminal station C (negative polarity) flows through the path C→r32→R3→E. One-end power is supplied between the terminal and the ground E. Therefore, power is supplied to the repeater between the terminal stations B and C, and communication between the terminal stations B and C can be continued.

As mentioned above, in a branching device that performs 3 branches to 3 terminal stations, even if a failure occurs in any terminal station, the other healthy 2
It can be switched so that a power supply path between terminal stations is formed. Therefore, since power is supplied to the repeater between the healthy terminal stations, communication between the healthy terminal stations can be continued.

[0033]

[Effect of the invention] As explained above, the first, second and third
In the invention, in a power supply line switching circuit configured using relays such as vacuum relays with a small number of contacts, by simply adding a switching relay R5 consisting of one vacuum relay,
The advantage is that even in the event of a failure on the first terminal A side, which is the main side, power can be switched to the repeater between the other healthy second and third terminal stations B and C and the branch device. There is. Further, in the fourth and fifth inventions, the system is constructed with four relays, and in the event of a failure on the terminal side, it is possible to switch the power supply path in the same way as described above, and it is possible to achieve economicalization. There are advantages.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of the first embodiment of the present invention at the time of a failure.

FIG. 3 is an explanatory diagram of a second embodiment of the present invention.

FIG. 4 is an explanatory diagram of a third embodiment of the present invention.

FIG. 5 is an explanatory diagram of a fourth embodiment of the present invention.

FIG. 6 is an explanatory diagram of a conventional example.

[Explanation of symbols]

R1 First relay R2 Second relay R3 Third relay R4 Fourth relay R5 Switching relay r11, r21, r31, r41
Break contacts r12, r22, r32, r42, r51, r52
make contacts

Claims (5)

[Claims] Claim 1: In a power supply path switching circuit that switches a power supply path that supplies power to a repeater between a first, second, and third terminal station and a branching device, the first, second, and third The first and second relays (R1
, R2) and a self-holding contact (r32, r42) that operates when one end of the power is supplied between the second or third terminal station and the ground.
When a failure occurs between the third and fourth relays (R3, R4), the first terminal station, and the branching device,
After performing both-end power feeding from the third terminal station, it operates during the both-end power feeding when switching to single-end power feeding, and when the both-end power feeding is performed, the first and second relays (R1, R2) are connected to the second and third relays. A power supply path switching circuit comprising: a switching relay (R5) having contacts (r51, r52) for connection to a terminal station side of the power supply path switching circuit. 2. Break contacts (r21, r41) of the second and fourth relays (R2, R4) connected in series to the first relay (R1) and the second relay (R2)
) are connected in series to the first and third relays (R1, R
3) in parallel with the break contacts (r11, r31), respectively, the make contacts (r51, r51,
r52) between the second terminal station and the ground,
The make contact (r) of the second relay (R2) connected in parallel
22) and a self-holding make contact (r42), the fourth relay (R4) is connected to the first relay (R4) connected in parallel between the third terminal station and ground. R1)
make contact (r12) and self-holding make contact (r
32) connect the third relay (R3) via
The power supply path switching circuit according to claim 1, characterized in that a diode (D1) is connected in series to the switching relay (R5). 3. The diode (D1) is connected in parallel to the series circuit of the switching relay (R5) and the diode (D1).
1) and a diode of opposite polarity and the second relay (R2)
2. The power supply path switching circuit according to claim 1, further comprising a series circuit connected to the power supply path switching circuit. 4. In a power supply path switching circuit that switches a power supply path that supplies power to a repeater between the first, second, and third terminal stations and a branching device, the first, second, and third relays are connected to each other. (R1, R2,
R3) and a switching relay (R5), and the first relay (R1) is provided between the first terminal station and the second terminal station.
and the break contact (r21) of the second relay (R2).
) are connected in series, and the second relay (R2) and the first and third relays (R1, R3) are connected between the first terminal station and the third terminal station. Break contact (r11, r
31) and a diode are connected in series, and in parallel to the series circuit of the second relay (R2) and the diode,
a diode with a polarity opposite to that of the diode and the switching relay (
R5), and the third relay (R3) and the make contact (r12) of the first relay (R1) are connected in series between the third terminal station and the ground. and the self-holding make contact (r32) of the third relay (R3) is connected in parallel to the make contact (r12), and the break contact (r2) of the second relay (R2)
1) and the make contacts (r51, r51, r51) of the switching relay (R5) in parallel with the series-connected break contacts (r11, r31) of the first and third relays (R1, R3), respectively.
52) is connected. 5. The power supply path switching circuit according to claim 4, wherein a make contact (r22) of said second relay (R2) is connected between said second terminal station and ground.