A novel branching unit provided. The branching unit may include a first port for connecting a first power conductor disposed in a first optical cable, a second port for connecting a second power conductor disposed in a second optical cable, and a third port for connecting a third power conductor and a fourth power conductor disposed in a branch cable. The third port may include a first sub-port and a second sub-port. The first sub-port may be configured to connect the third power conductor of the branch cable. The second sub-port may be configured to connect the fourth power conductor of the branch cable.

In order to enable switching control over power-feeding paths even in the event of a ground fault or an open fault in a power-feeding path, the submarine branching unit is provided with: a switching circuit which switches multiple power-feeding paths formed among a first through a third power-receiving ports; a control circuit which receives power from a power-feeding path formed between the first power-receiving port and the second power-receiving port and controls the switching circuit; and a connection circuit which connects the control circuit between the third power-receiving port and a sea-earth when no power is supplied to the control circuit from the power-feeding path formed between the first power-receiving port and the second power-receiving port.

In one embodiment, a switched amplifier is provided to amplify a data transmission. The switched amplifier may use a control signal that is received via a control signal channel in a transmission cable. Also, the switched amplifier may detect signal power to determine whether the data transmission is received at one of a first port and a second port. Data transmissions via the data transmission channel occur in a first direction and a second direction in a same frequency range in a time division multiplex (TDD) mode. Also, the control signal and data transmission are diverted from the transmission cable that transmits a type of signal different from the control signal and the data transmission. The switched amplifier is controlled based on the control signal or the signal power detected. The amplified signal is diverted in the first direction or the second direction via the data transmission channel back to the transmission cable.

In one embodiment, a switched amplifier is provided to amplify a data transmission. The switched amplifier may use a control signal that is received via a control signal channel in a transmission cable. Also, the switched amplifier may detect signal power to determine whether the data transmission is received at one of a first port and a second port. Data transmissions via the data transmission channel occur in a first direction and a second direction in a same frequency range in a time division multiplex (TDD) mode. Also, the control signal and data transmission are diverted from the transmission cable that transmits a type of signal different from the control signal and the data transmission. The switched amplifier is controlled based on the control signal or the signal power detected. The amplified signal is diverted in the first direction or the second direction via the data transmission channel back to the transmission cable.

In order to supply drive elements with necessary power supply while maintaining a constant current power supply system even in a case where ON/OFF control of a power source or various operation settings of the drive elements are executed at high speed, a constant current supply device 10 is provided with: a constant voltage acquisition means 20 for extracting a constant voltage from a supplied constant current; a conversion means 30 for converting the extracted constant voltage to a drive current of a desired size and outputting same; and a control means 60 for controlling the size of the drive current flowing to a current control element 5k according to control content of n-sets of drive elements 41-4n, current control elements 51-5n, and a drive element 4k, which are connected in parallel to each other, and into which the drive current is inputted.

In order to supply drive elements with necessary power supply while maintaining a constant current power supply system even in a case where ON/OFF control of a power source or various operation settings of the drive elements are executed at high speed, a constant current supply device 10 is provided with: a constant voltage acquisition means 20 for extracting a constant voltage from a supplied constant current; a conversion means 30 for converting the extracted constant voltage to a drive current of a desired size and outputting same; and a control means 60 for controlling the size of the drive current flowing to a current control element 5k according to control content of n-sets of drive elements 41-4n, current control elements 51-5n, and a drive element 4k, which are connected in parallel to each other, and into which the drive current is inputted.

[Problem] To suppress current flowing to a contact of a relay when grounding a device to be grounded by connecting the contact of the relay, and to suppress arc discharge between relay contacts when the grounding state of the device to be grounded is released by disconnecting the relay contact. [Solution] A grounding circuit equipped with: a first relay contact connected to a device to be grounded; a resistor that is connected between the first relay contact and an earth, and that suppresses current flowing to the first relay contact when the contact of the first relay is closed; and a second relay contact that is connected in parallel with the resistor, and that is closed before the first relay contact is opened when the grounding state of the device to be grounded is released.

[Problem] To suppress current flowing to a contact of a relay when grounding a device to be grounded by connecting the contact of the relay, and to suppress arc discharge between relay contacts when the grounding state of the device to be grounded is released by disconnecting the relay contact. [Solution] A grounding circuit equipped with: a first relay contact connected to a device to be grounded; a resistor that is connected between the first relay contact and an earth, and that suppresses current flowing to the first relay contact when the contact of the first relay is closed; and a second relay contact that is connected in parallel with the resistor, and that is closed before the first relay contact is opened when the grounding state of the device to be grounded is released.

There is provided an outdoor tap comprising an input and an output connectable to a signal path carrying electrical power and an RF signal, and a plurality of output ports connectable to users of a broadband network, wherein a power return path is provided between each output port and the input, the power return path selectively actuable to transmit electrical power from a user to power elements disposed in the signal path. A switch is disposed in the power return path, the switch selectively operable to activate the power return path. The switch is responsive to AC power from a user when a main electrical grid supply is interrupted.

There is provided an outdoor tap comprising an input and an output connectable to a signal path carrying electrical power and an RF signal, and a plurality of output ports connectable to users of a broadband network, wherein a power return path is provided between each output port and the input, the power return path selectively actuable to transmit electrical power from a user to power elements disposed in the signal path. A switch is disposed in the power return path, the switch selectively operable to activate the power return path. The switch is responsive to AC power from a user when a main electrical grid supply is interrupted.