JPH04256225A - Feeding method and feed line switching circuit for sea-bottom cable communication system - Google Patents

Abstract

PURPOSE:To prevent hot switching and to switch a feed line at the time of reconstructing the feed line when a fault occurs. CONSTITUTION:Respective sea-bottom branching devices BU1, BU2... are provided with feed line switching circuits in which the size of an operation current differs by changing the direction of the current. The feed line switching circuits of respective sea-bottom branching devices BU1, BU2... are constituted so that respective operation current values alpha, beta... differ as against the same feed current direction in both end feed line which is to be set. In a station on the side of a non-fault line on the side of a fault-side sea-bottom branching device to which the both end feed line is to be set and a station on the side of a non-fault-side sea-bottom branching device, feeding is executed in the feed current direction where the feed line switching circuit in the fault-side sea-bottom branching device operates with the small operation current and the feed line is switched so that the fault line is separated. Then, the large feed current is fed in the same feed current direction, the feed line switching circuit in the non-fault-side sea-bottom branching device is switched and the feed line is set at the time of raising a system when the fault occurs.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a power feeding method used in a submarine cable communication system in which a submarine cable such as an optical submarine cable is branched underwater using an underwater branching device to perform multipoint communication between landing stations, and a power feeding method used therein. The present invention relates to a path switching circuit.

[0002] In optical submarine cable communication systems, when a faulty line occurs due to a ground fault in a submarine cable, the power supply line is switched to disconnect the faulty line from the system. It is necessary to perform switching to prevent damage to the underwater branching equipment due to hot switching or the like.

0003

[Prior Art] In a system in which multiple underwater branching devices are used in one submarine cable communication system to perform multipoint communication, the underwater branching devices are provided with a power supply line switching function, and a certain branch (branch line) In the event of a failure, the power supply path is switched to disconnect the faulty line, ensuring communication on the remaining cables. In order to identify each of multiple underwater branch devices in one system and switch the power supply route, each underwater branch device is equipped with a power supply route switching circuit (switch) with a different operating current, and this is connected to the shore. Switching is performed by controlling the magnitude of the power supply current from the station and operating it separately, but when supplying power for this switching, it is necessary to adjust the power supply voltage to avoid so-called hot switching.

[0004] Such a conventional power supply path switching method will be explained below with reference to FIG. 15. In FIG. 14, A, B, C
, D are landing stations at different locations, BU1 and BU2 are underwater branching devices, and four landing stations A, B, C, and D are connected by submarine cables branched by the underwater branching devices BU1 and BU2. Here, the power supply switching circuit of the underwater branching device BU1 is set to operate with an operating current α, and the power supply switching circuit of the underwater branching device BU2 is set to operate with an operating current β. This operating current is assumed to be α<β. These underwater branching devices B
The power supply path switching circuits of U1 and BU2 connect each branch power supply path within the device while insulating it from the seabed ground when no power is being supplied, and switch one of the branch power supply paths by passing operating currents α and β, respectively. One branch is grounded to the seabed, and the remaining branch power supply lines are interconnected.

[0005] The normal startup operation of this system will be explained. Now, assume that a power supply path is set so that power is supplied at both ends between landing stations A and D, and power is supplied at one end between landing stations B and C. Switching of the power supply line of the underwater branching device is performed by supplying operating current to the power supply line switching circuit, but at that time, the power supply voltage from the landing station at both ends is adjusted so that the ground potential of the power supply line switching circuit is zero. There is a need to. This is because if the power supply switching circuit has a large ground potential, there is a risk of arc discharge occurring at relay contacts, etc. during switching, and the resulting surge may damage equipment, resulting in so-called hot switching. .

Therefore, first, landing stations A and D control their power supply current and power supply voltage, and supply power by setting the power supply current to α and the ground potential of the underwater branch unit BU1 to zero [FIG.
See 5 (1)]. As a result, in the underwater branching device BU1, the branch power supply path to the landing station B is grounded under the sea, and one-end power supply by the landing station B becomes possible.

Next, the power supply current is set to β, and the underwater branching device BU2
Power is supplied by setting the potential to the ground to zero [see (2) in FIG. 15]. As a result, the landing station C is installed in the underwater branching device BU2.
A branch power supply path to the base is grounded under the sea, allowing one-end power supply by landing station C. Furthermore, since landing stations B and C are separated, power is supplied from both ends between landing stations A and D.

[0008] In this system, if switching is performed at the underwater branch unit BU2 first, the operating current β of the power supply switching circuit is larger than the operating current α of the underwater branch unit BU1 side. The power supply path switching circuit of the device BU1 also operates at the same time, but since the ground potential of this underwater branch device BU1 is not zero, there is a risk that the above-mentioned hot switching may occur during its operation. Therefore, it is necessary to switch the power supply path in the order of the underwater branching devices BU1 and BU2.

[0009]

In the above-described system, it is assumed that a ground fault occurs in the cable between the underwater branch unit BU2 and the landing station D, as shown in FIG. In this case, it is necessary to disconnect the faulty line (branch line to landing station D) and reconstruct the power supply line using the remaining cable. For this reason, the system is temporarily returned to a non-power-supplied state, and restarted by supplying power at both ends between landing stations A and C, supplying power at one end at landing station B, and disconnecting landing station D. At this time as well, since the operating current is in the relationship α<β, it is desired to operate the power supply line switching circuit in the order of underwater branching units BU1 and BU2, but the potential becomes zero at the ground fault point on the underwater branching unit BU2 side. Since it is fixed, it is no longer possible to control the power supply voltage between landing stations A and D to bring the ground potential of underwater branch unit BU1 to zero, and
U1 is switched with the potential to ground. In addition, if the underwater branch unit BU2 side, which has a large ground potential, tries to disconnect the faulty line first, the operating current of the underwater branch unit BU2 is β, so the underwater branch unit B
As mentioned above, switching is also performed on the U1 side.

[0010] The present invention has been made in view of the above problems, and its purpose is to prevent hot switching while switching the power supply route when the power supply route is rebuilt in the event of a failure. There is a particular thing.

[0011]

[Means for Solving the Problems] FIG. 1 shows a diagram illustrating the principle of the present invention. In order to solve the above problems, a power feeding method for a submarine cable communication system according to the present invention connects a submarine cable to a plurality of underwater branching devices BU1, BU2...
This is a power supply method for a submarine cable communication system that connects multiple stations A, B, C, D, etc. by branching off at Each underwater branching device BU1, BU2... is equipped with
The power supply line switching circuits of each underwater branch unit BU1, BU2... are configured so that the operating current values α, β... are different for the same power supply current direction in the two-end power supply line to be set, so that when a fault occurs, When starting up the system, first switch the power supply line at the faulty underwater branching device between the non-faulty line side station on the faulty underwater branching device side and the station on the non-faulty underwater branching device side, where you want to set up a double-end power feeding path. The power supply path is switched to isolate the faulty line by feeding power in the direction of the feed current where the circuit operates with a small operating current, and then a large power supply current is fed in the same direction of the feed current to connect the non-faulty underwater branch equipment. The power supply route is set by switching the power supply route switching circuit.

[0012] In another embodiment of the power feeding method for a submarine cable communication system according to the present invention, a submarine cable is branched by a plurality of underwater branching devices BU1, BU2, and so on, and is connected to multiple points A, B, C, D, etc. ... In a submarine cable communication system that connects multiple underwater branching devices, different operating currents α, β, etc. are assigned to the power switching circuits of the underwater branching devices, and the switching circuits are sequentially assigned starting from the power switching circuit of the underwater branching device with the lowest operating current. A power supply method that switches the power supply path by operating the
A plurality of underwater branching devices BU1, BU2... are arranged in series in a power supply line, and power is supplied from both ends of the line, and when the power supply current flows in one direction and when it flows in the opposite direction, multiple The order of operation of the power supply line switching circuits of the underwater branching devices BU1, BU2, etc. is reversed.

[0013] Furthermore, in the power feeding method for a submarine cable communication system according to the present invention, in each of the above-mentioned power feeding methods, an underwater branching device that does not have a power feeding path switching function is installed in some or all of the branching power paths of the underwater branching device. It is something that

Further, the feed path switching circuit according to the present invention has a first circuit that is connected in parallel to a drive circuit that passes an operating current for driving the feed path switching circuit, and that passes a current of a first magnitude only in one direction. a second current shunt circuit that is connected in parallel to the drive circuit and passes a current having a second magnitude different from the first magnitude only in the opposite direction to the first current shunt circuit; It is equipped with the following.

The power supply method for a submarine cable communication system according to the present invention uses the above-described power supply line switching circuit of the present invention as the power supply line switching circuit in each of the above-mentioned power supply methods.

[0016]

[Operation] The principle of operation of the present invention will be explained using the submarine cable communication system shown in FIG. 1 as an example. In the figure, A, B, C, and D are stations such as landing stations, and BU1 and BU2 are underwater branching devices.The operating current of the underwater branching devices BU1 and BU2 is from the underwater branching device BU1 to BU2 ( When the power supply current flows in the direction of → mark), the underwater branching device BU1 becomes α, the underwater branching device BU2 becomes β, and on the other hand, the underwater branching device BU2 becomes
When the power supply current flows from BU1 direction (← mark direction in the figure), the underwater branching device BU1 is β, and the underwater branching device BU2 is β.
becomes α. This operating current has a relationship of α<β.

The normal start-up operation of this system is as described in the "Prior Art" section. Now, it is assumed that a ground fault has occurred in the cable between the underwater branching device BU2 and the landing station D. At this time, a both-end power supply path is set up between stations A and C to disconnect the faulty line to station D. However, if the power supply current is passed from station A to station C, the invention will solve the problem. Problems such as those explained in the section ``Issues to be solved'' arise.

Therefore, the feeding current direction between stations A and C is
Stations A and C control the direction of the current so that it flows in the A direction (← direction). As a result, the operating current of the underwater branching device BU2 becomes α, and the operating current of the underwater branching device BU1 becomes β. Here, since α<β, the underwater branching devices BU2 and B
The switching is performed in the order of U1. That is, first, α is passed as a power supply current, and the faulty line to station D is disconnected at the underwater branch unit BU2. As a result, the ground potential of the underwater branching device BU2 is no longer fixed due to the influence of the zero potential at the fault point, so when switching the station B side power supply line in the next underwater branching device BU1 for underwater grounding, the operation It becomes possible to control the stations A and C at both ends to set the current to β and the ground potential of the underwater branching device BU1 to zero, and hot switching can be prevented.

Furthermore, the power supply path switching circuit according to the present invention can be used as the power supply path switching circuit used in the above-described power feeding method. In the power supply path switching circuit according to the present invention,
For example, if the current flowing through the first current shunt circuit is made larger than the current flowing through the second current shunt circuit, when the supply current flows in the current direction of the first current shunt circuit, the current will be shunted to the drive circuit of the power supply path switching circuit. The operating current that is applied is α, and the operating current that is shunted to the drive circuit when the supply current is passed in the current direction of the second current shunting circuit is β, so that α<β. Therefore, in this power supply path switching circuit, by changing the direction in which the operating current flows, the magnitude of the operating current can be changed.

[0030]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 2 shows a submarine cable communication system using a power feeding method as an embodiment of the present invention. In the figure, A,
B, C, and D are landing stations, and BU1 and BU2 are underwater branching devices. K1 to K in the underwater branching devices BU1 and BU2
4 is a relay, and the arrows attached to each relay K1 to K4 represent the direction of the operating current in which each relay operates, α,
β represents the magnitude of the operating current at which each relay operates, and this operating current has a relationship of α<β. Also each relay K1~K
4 contacts are indicated by ■ to ■ in correspondence with the numbers of each relay. Note that these notations are the same in each embodiment described later.

In this embodiment, a combination of relays K1 and K3 with different operating current directions and magnitudes, or a combination of relays K2 and
By the combination of and K4, the switching mode of the power supply path is made to differ depending on the direction and magnitude of the power supply current.

[0032] When the system is normally started up, it is assumed that, for example, the landing stations A and D are set to have power supplied at both ends, and the landing stations B and C are set to be powered at one end. . To do this, first, feed current α is passed in the direction from landing station A to landing station D, and
Activate relay K1 of U1, open and close its contact ■ to ground the branch power supply line on the landing station B side underwater, and then apply operating current β to operate relay K1 of underwater branch device BU2, and connect its contact ■Open and close the branch power supply line on the landing station C side to the underwater ground. In addition, each underwater branching device BU1, BU2
When switching, the power supply voltage is adjusted at the landing stations at both ends so that the ground potential is set to zero, and this is the same in each of the embodiments described below.

In this embodiment, for example, underwater branching device B
Assume that a ground fault has occurred in the cable between U2 and landing station D. In this case, the entire system is temporarily returned to the unpowered state, and then the power supply path is switched so that the landing stations A and C are supplied with power at both ends, and the landing station B is supplied with power at one end.

Between the landing stations A and C, the direction of the power supply current of the landing stations A and C is adjusted so that the power supply current flows from the landing station C in the A direction (← direction). First, when the power supply current α is applied, the relay K4 in the underwater branch unit BU2 operates to open and close its contact ■, thereby grounding the branch power supply path to the faulty landing station D under the sea and connecting it to the landing station A. , disconnect from the power supply path between C and C. After that, the power supply current β is applied to the underwater branching device BU1.
The relay K3 is operated to open and close its contact (2), thereby grounding the landing station B underwater.

Another embodiment of the invention is shown in FIG. FIG. 4 shows power supply paths that can be set in the embodiment of FIG. In the embodiment of FIG. 2 described above, the underwater branching device BU1
If a ground fault occurs between BU2 and BU2, the entire system will go down. The embodiment shown in FIG. 3 is an improvement on this point. In this embodiment, each relay K1~
The operating current of K6 is α=200mA, β=400mA, γ
There are three types: = m600A.

First, under normal conditions, power is supplied at both ends between landing stations A and D, and power is supplied at one end at each of landing stations B and C. To do this, at the time of startup, first 200m from landing station A in direction D.
A feed current is passed to relay K6 of underwater branching device BU2.
The landing station C side is disconnected and grounded underwater, and then a 400 mA power supply current is applied to the underwater branch unit BU1.
Activate relay K6 to disconnect the landing station B side and ground it underwater.

For example, the underwater branching device BU2 and the landing station D
It is assumed that a ground fault has occurred in the cable between the two. At this time, power is supplied at both ends between landing stations A and C, and power is supplied at one end at landing station B. For that purpose, 200m from landing station C in direction A.
A power supply current is applied to activate relays K4 and K5 of underwater branching device BU2 to disconnect the landing station D side and ground it underwater, and then a 400 mA power supply current is applied to underwater branching device B.
Activate relay K2 of U1 to disconnect the landing station B side and ground it underwater.

FIG. 5 shows yet another embodiment of the invention. Further, FIG. 6 shows power supply paths that can be set in the embodiment of FIG. The operating current of each relay is α=200mA, β=
The current is 400 mA, and the relay K5 is a relay that operates with operating current in both directions (←→ direction).

First, under normal conditions, power is supplied at both ends between landing stations A and D, and power is supplied at one end at each of landing stations B and C. To do this, at the time of startup, first 200m from landing station A in direction D.
Relay K2 of underwater branching device BU2 by passing power supply current A
and operate K5 to disconnect the landing station C side and connect it to underwater ground, then apply a 400mA power supply current and operate relays K5 (already operated at 200A) and K6 of the underwater branch unit BU1 to disconnect the landing station B side. Separate it and ground it underwater. Note that the same operation occurs when the feeding current is passed in the direction A from the landing station D.

For example, the underwater branching device BU2 and the landing station D
It is assumed that a ground fault has occurred in the cable between the two. At this time, power is supplied at both ends between landing stations A and C, and power is supplied at one end at landing station B. To do this, you need to travel 200m from landing station A in the direction of C.
A power supply current is applied to operate relays K1 and K5 of the underwater branching device BU2, and the landing station D side is disconnected and grounded under the sea.Then, a 400A power supply current is applied to the underwater branching device BU.
Activate relays K5 (already operated at 200 mA) and K6 of No. 1 to disconnect the landing station B side and ground it underwater.

FIG. 7 shows yet another embodiment of the present invention. Further, FIG. 8 shows power supply paths that can be set in the embodiment of FIG. The operating current of each relay is α=200mA, β=
400 mA, and relays K1 and K2 are relays in which the magnitude of the operating current changes by changing the direction of the operating current. By using such relays K1 and K2 in the power supply path switching circuit, the switching mode of the power supply path switching circuit can be changed depending on the direction and magnitude of the power supply current. A configuration example of such relays K1 and K2 will be described in detail later.

First, under normal conditions, power is supplied at both ends between landing stations A and D, and power is supplied at one end at each of landing stations B and C. To do this, at the time of startup, first 200m from landing station D in direction A.
Relay K1 of underwater branching device BU1 by passing power supply current A
K2 is operated to disconnect the landing station B side and ground it in the sea, and then a 400 mA feeding current is applied to operate the relay K1 of the underwater branching device BU2 to disconnect the landing station C side and ground it in the sea.

For example, the underwater branching device BU2 and the landing station D
It is assumed that a ground fault has occurred in the cable between the two. At this time, power is supplied at both ends between landing stations A and C, and power is supplied at one end at landing station B. To do this, you need to travel 200m from landing station A in the direction of C.
A power supply current is applied to operate relay K2 of underwater branch unit BU2, disconnecting the landing station D side and grounded under the sea.Next, 400 mA of power supply current is applied to operate relays K1 and K2 of underwater branch unit BU1. Disconnect the landing station B side and ground it underwater.

FIG. 9 shows yet another embodiment of the present invention. Further, FIG. 10 shows power supply paths that can be set in the embodiment of FIG. The operating current of each relay is undersea branch device B
α = 200 mA, β = 400 mA on the U1 side, α = 200 mA, β = 400 mA on the underwater branch unit BU2 side,
The relays K1 and K2 of the underwater branching device BU2 are relays in which the magnitude of the operating current changes by changing the direction of the operating current.

First, under normal conditions, power is supplied at both ends between landing stations A and D, and power is supplied at one end at each of landing stations B and C. To do this, at the time of startup, first 400m from landing station D in direction A.
Relay K2 of underwater branching device BU1 by passing power supply current A
The landing station B side is disconnected and grounded underwater, and then a 600 mA power supply current is applied to the underwater branch unit BU2.
Activate relay K2 to disconnect the landing station C side and ground it underwater.

For example, the underwater branching device BU2 and the landing station D
It is assumed that a ground fault has occurred in the cable between the two. At this time, power is supplied at both ends between landing stations A and C, and power is supplied at one end at landing station B. To do this, you need to travel 200m from landing station A in the direction of C.
A power supply current is applied to operate relay K1 of underwater branching device BU2, disconnecting the landing station D side and grounding it under the sea.Next, a 400mA power supply current is applied and relay K6 of underwater branching device BU1 is operated to land the landing station. Disconnect the station B side and ground it underwater.

Next, the structure of a relay such as relays K1 and K2 used in the embodiments shown in FIGS. 7 and 9 described above, in which the magnitude of the operating current changes by changing the direction of the power supply current, will be described. FIG. 11 shows an example of this configuration. In the figure, L is a relay coil as a drive circuit of the power supply path switching circuit, and this relay coil L has a diode D1 and an adjustment resistor R1.
A series circuit of , and a series circuit of diode D2 and adjustment resistor R2 are connected in parallel. The diode D1 and the diode D2 are used to limit the direction of current, and are connected with opposite polarities. Still adjusting resistors R1 and R2
have different resistance values.

With this configuration, when the feed current is supplied in the ← direction, part of it is shunted to the adjustment resistor R1 side, and when it is supplied in the → direction, a part of it is shunted to the adjustment resistor R2 side. Since the adjustment resistors R1 and R2 have different resistance values, their respective shunt current values are different, and in the end, in order to flow an operating current of more than a certain value to drive the relay coil L, it is necessary to move it in the ← direction. The magnitude of the power supply current is different when the power supply current is flowing and when the power supply current is flowing in the → direction. For example, if adjustment resistance R1>adjustment resistance R2, ←
If the feeding current in the direction is α, the relay will not operate unless a feeding current β larger than α is passed in the → direction.

FIG. 12 shows another configuration example of a device having different operating current values in the operating current direction. This circuit differs from the circuit shown in FIG. 11 described above in that a series circuit of Zener diodes ZD1 and ZD2 connected in series with opposite polarities is connected in parallel to the relay coil L. The Zener diodes ZD1 and ZD2 are a protection circuit that prevents overvoltage from being applied to the relay coil.

In this circuit, when a feeding current is passed in the → direction and the feeding current is gradually increased from zero, this feeding current is divided into the relay coil L side and the adjustment resistor R2 side. Eventually, the relay operates at the current value set by the regulating resistor R2. If the supply current is further increased,
Current also begins to flow through the Zener diode ZD2, and the Zener voltage fixes the voltage across the relay coil to a constant value, so the operating current flowing through the relay coil L can be limited to protect the coil L. The coil can be protected by the Zener diode ZD1 in the same way when the feeding current is passed in the ← direction.

FIG. 13 similarly shows another configuration example of a device in which the operating current value differs in the operating current direction. This circuit differs from the circuit of FIG. 11 described above in that a protective Zener diode ZD1 is connected in parallel to the adjustment resistor R1.
A protective Zener diode ZD2 having a polarity opposite to that of the Zener diode ZD1 is connected in parallel to the adjustment resistor R2.

The operation of this circuit is almost the same as that shown in FIG. In other words, when the feeding current flows in the → direction,
When the power supply current is gradually increased from zero, this power supply current is divided into the relay coil L side and the adjustment resistor R2 side. Eventually, the relay operates at the current value set by the regulating resistor R2. When the power supply current is further increased, current also begins to flow through the Zener diode ZD2, and the voltage across the relay coil is fixed at a constant value due to the Zener voltage, so the operating current flowing through the relay coil L is limited and the coil L is protected. be able to. The coil can be protected by the Zener diode ZD1 in the same way when the feeding current is passed in the ← direction.

As a device that changes the magnitude of the operating current depending on the current direction, in addition to the devices shown in FIGS. 11 to 13 described above, the circuit used in the embodiment of FIG. 2, that is, the circuit shown in FIG. Of course it can be realized, but by configuring as described above, the number of relays can be configured with one,
Moreover, the contact configuration can also be simplified.

[0060]

[Effects of the Invention] As explained above, according to the power supply method of the present invention, when rebuilding the power supply system in the event of a failure, it is possible to switch the power supply route at each underwater branch device while preventing so-called hot switching. This makes it possible to improve the reliability of submarine cable communication systems. Further, according to the power supply path switching circuit of the present invention, the circuit can be downsized and simplified.

[Brief explanation of the drawing]

FIG. 1 is a diagram for explaining the principle of the present invention.

FIG. 2 is a block diagram showing a submarine cable communication system using a power feeding method as an embodiment of the present invention.

FIG. 3 is a block diagram showing another embodiment of the present invention.

FIG. 4 is a diagram illustrating aspects of a power supply path that can be set in the embodiment system of FIG. 3;

FIG. 5 is a block diagram showing another embodiment of the present invention.

FIG. 6 is a diagram illustrating aspects of a power supply path that can be set in the embodiment system of FIG. 5;

FIG. 7 is a block diagram showing still another embodiment of the present invention.

8 is a diagram illustrating aspects of a power supply path that can be set in the embodiment system of FIG. 7. FIG.

FIG. 9 is a block diagram showing still another embodiment of the present invention.

10 is a diagram illustrating aspects of a power supply path that can be set in the embodiment system of FIG. 9; FIG.

FIG. 11 is a diagram showing an example of a power supply path switching circuit as an embodiment of the present invention.

FIG. 12 is a diagram showing an example of a power supply path switching circuit as another embodiment of the present invention.

FIG. 13 is a diagram showing an example of a power supply path switching circuit as still another embodiment of the present invention.

FIG. 14 is a diagram showing an example of a circuit in which contacts at the same location operate at different current values depending on the current direction.

FIG. 15 is a diagram illustrating a conventional method of switching power supply lines in a submarine cable communication system.

FIG. 16 is a diagram for explaining problems with the conventional method.

[Explanation of symbols]

A, B, C, D Landing station BU1 BU2 Undersea branching device K1~K7 Relay ■~■　Contact points of each relay K1~K6 D1, D2 Diode R1, R2 Adjustment resistance L Relay coil

Claims (5)

[Claims] [Claim 1] A submarine cable is connected to a plurality of underwater branching devices (
Branch at BU1, BU2...) and connect to multiple stations (A, B,
This is a power supply method for a submarine cable communication system that connects C, D... The device's power supply path switching circuit is configured to have different operating current values for the same power supply current direction in the two-end power supply path to be set, and when starting up the system in the event of a failure, it is difficult to set the two-end power supply path. Between the non-faulty line side station on the faulty underwater branching device side and the station on the non-faulty underwater branching device side, first, the power supply path switching circuit in the faulty underwater branching device supplies power in the feed current direction that operates with a small operating current. The power supply path was switched to isolate the faulty circuit, and then a large power supply current was fed in the same direction of current, and the power supply path switching circuit in the non-faulty underwater branch device was switched to set up the power supply path. Power supply method. [Claim 2] A submarine cable is connected to a plurality of underwater branching devices (
Branch at BU1, BU2...) and connect to multiple points (A, B, C
, D...), a different operating current is assigned to each of the power supply switching circuits of the plurality of underwater branching devices, and sequentially starting from the power supply switching circuit side of the underwater branching device with the smaller operating current. A power supply method that switches the power supply route by operating the power supply route, in which a plurality of underwater branch devices are arranged in series in the power supply route, and power is supplied from both ends of the power supply route, and the supply current flows in one direction and in the opposite direction. A power feeding method for a submarine cable communication system in which the operating order of the power feeding path switching circuits of the plurality of underwater branching devices is reversed when the power is supplied to the submarine cable communication system. 3. The power feeding method according to claim 1, wherein an underwater branching device having no power feeding path switching function is installed in some or all of the branching power feeding paths of the underwater branching device. 4. A first current shunting circuit that is connected in parallel to a drive circuit that passes an operating current for driving the power supply path switching circuit and that passes a current of a first magnitude only in one direction; A power supply path switching circuit comprising: a second current shunting circuit connected in parallel to the circuit and passing a current having a second magnitude different from the first magnitude only in a direction opposite to the first current shunting circuit. 5. The method of feeding power to a submarine cable communication system according to claim 1, wherein the power feeding path switching circuit according to claim 2 is used as the feeding path switching circuit.