Electricity: electrical systems and devices – Safety and protection of systems and devices – Feeder protection in distribution networks
Reexamination Certificate
2000-11-14
2004-03-30
Jackson, Stephen W. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
Feeder protection in distribution networks
C361S064000, C361S078000
Reexamination Certificate
active
06714394
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method and apparatus of switching the connection of electric power feeding lines from which electric power is supplied to a signal passing through an optical fiber transmission path (for example, a transmission path of a submarine cable) through a repeater. Also, the present invention relates to an electric power feeding line switching system in which communication between terminal stations (for example, land-based terminal stations) is performed through the optical fiber transmission paths connected with each other in an optical fiber transmission path branching apparatus and the repeater while electric power is supplied from the electric power feeding lines to the signal of the optical fiber transmission paths.
2. Description of Related Art
A conventional electric power feeding line switching apparatus and a conventional electric power feeding line switching system, “Switching Method and Switching Circuit for Feeder Line of Transmission Path” disclosed in Published Unexamined Japanese Patent Application No. JP1-243734 is known as an example of a conventional electric power feeding line switching method.
FIG. 11
is a constitutional view of a conventional electric power feeding line switching system in which submarine cable transmission paths and repeaters are arranged so as to supply electric power from electric power feeding lines, of which the connection is switched in a conventional electric power feeding line switching apparatus according to a conventional electric power feeding line switching method disclosed in the Application No. JP1-243734, to a signal of the submarine cable transmission paths through the repeaters.
In
FIG. 11
,
1
indicates a first land-based terminal station,
2
indicates a second land-based terminal station,
3
indicates a third land-based terminal station,
8
indicates a submarine branching apparatus in which a plurality of submarine cable transmission paths are connected with each other at a branching point
24
,
21
indicates a first submarine cable transmission path connecting the first land-based terminal station
1
and the submarine branching apparatus
8
,
22
indicates a second submarine cable transmission path connecting the second land-based terminal station
2
and the submarine branching apparatus
8
,
23
indicates a third submarine cable transmission path connecting the third land-based terminal station
3
and the submarine branching apparatus
8
,
11
indicates a repeater arranged on the first submarine cable transmission path
21
,
12
indicates another repeater arranged on the first submarine cable transmission path
21
,
13
indicates a repeater arranged on the second submarine cable transmission path
22
, and
14
indicates another repeater arranged on the second submarine cable transmission path
22
. Each of the submarine cable transmission paths
21
,
22
and
23
is formed of an optical fiber. An optical signal, which transmits through the first submarine cable transmission path
21
and is attenuated in a long-distance transmission, is amplified in the repeaters
11
and
12
. An optical signal, which transmits through the second submarine cable transmission path
22
and is attenuated in a long-distance transmission, is amplified in the repeaters
13
and
14
. A length of the third submarine cable transmission path
23
is comparatively short. Therefore, an optical signal of the third submarine cable transmission path
23
is not substantially attenuated, and no repeater is arranged on the third submarine cable transmission path
23
.
Also,
5
indicates a first electric power feeding line through which electric power is supplied from the first land-based terminal station
1
to the repeaters
11
and
12
,
6
indicates a second electric power feeding line through which electric power is supplied from the second land-based terminal station
2
to the repeaters
13
and
14
,
7
indicates a third electric power feeding line extending from the third land-based terminal station
3
to the submarine branching apparatus
8
, and
8
a
indicates an electric power feeding line switching circuit (or a conventional electric power feeding line switching apparatus) arranged in the submarine branching apparatus
8
. The electric power feeding line switching circuit
8
a
normally connects the first electric power feeding line
5
and the second electric power feeding line
6
and normally disconnects the third electric power feeding line
7
from the electric power feeding lines
5
and
6
. Therefore, electric power is supplied to the repeaters
11
to
14
to perform the communication between the land-based terminal stations
1
and
2
. Also, when a fault occurs in the electric power feeding line
5
(or
6
), the electric power feeding line switching circuit
8
a
switches from the connection between the electric power feeding lines
5
and
6
to another connection between the electric power feeding lines
6
(or
5
) and
7
.
Also,
23
a
indicates a control signal line through which a control signal is transmitted from the third land-based terminal station
3
to the electric power feeding line switching circuit
8
a
to switch a connection relationship among the electric power feeding lines
5
to
7
in the electric power feeding line switching circuit
8
a
. The control signal line
23
a
is formed of an optical fiber.
An operation of the conventional electric power feeding line switching system in the above configuration is described.
Electric power is supplied to the repeaters
11
to
14
through the electric power feeding lines
5
and
6
, and an optical signal is normally transmitted between the land-based terminal stations
1
and
2
through the submarine cable transmission paths
21
and
22
while amplifying the optical signal in the repeaters
11
to
14
.
When a fault occurs, for example, in the first electric power feeding line
5
placed between the first land-based terminal station
1
and the submarine branching apparatus
8
, a control signal is transmitted from the third land-based terminal station
3
to the submarine branching apparatus
8
through the control signal line
23
a
, and a switching circuit of the electric power feeding line switching circuit
8
a
is operated according to the control signal. The operation of the switching circuit is such that an end of the first electric power feeding line
5
, in which the fault occurs, is earthed in the submarine branching apparatus
8
to disconnect the first electric power feeding line
5
from the electric power feeding lines
6
and
7
, and the third electric power feeding line
7
is connected with the second electric power feeding line
6
to enable communication between the land-based terminal stations
2
and
3
through the submarine cable transmission paths
22
and
23
.
Therefore, even though a fault occurs in the first electric power feeding line
5
, the first electric power feeding line
5
is disconnected from the electric power feeding lines
6
and
7
, and the third electric power feeding line
7
is connected with the second electric power feeding line
6
. Accordingly, electric power can be supplied to the repeaters
13
and
14
through the electric power feeding line
6
connected with the electric power feeding line
7
, and a communication between the land-based terminal stations
2
and
3
can be maintained.
However, in cases where a distance between the land-based terminal station
3
and the submarine branching apparatus
8
is long, because the third submarine cable transmission path
23
is lengthened, the control signal is attenuated. In this case, there is a case where the switching circuit of the electric power feeding line switching circuit
8
a
cannot be correctly operated according to the attenuated control signal. Therefore, there is a problem that it is required to shorten a distance between the land-based terminal station
3
and the submarine branching apparatus
8
or to additionally arrange one or more rep
Kumayasu Satoshi
Nakagawa Eiichi
Jackson Stephen W.
Mitsubishi Denki & Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
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