Abstract: The invention provides an electricity distribution system, which can keep a voltage to ground low, and can commonly detect abnormity, such as an electrical leak etc. produced in AC and DC feed lines. An AC-DC converter 21 is installed between the AC feed line (branch electrical circuit Lb) of a single phase three wire system for supplying the power to AC devices 41, and the DC feed line (main electrical circuit Ld) of a three wire system for supplying the power to DC devices. The DC feed line comprises a neutral wire N commonly connected to a neutral wire N of the AC feed line within the AC-DC converter 21, a positive voltage wire L+ having a positive electrical potential to an electrical potential of its neutral wire N, and a negative voltage wire L? having a negative electrical potential to the electrical potential of its neutral wire N. A voltage of +150 [V] is applied to the positive voltage wire L+, and a voltage of ?150 [V] is applied to the negative voltage wire L?.

Abstract: A DC distribution board comprises, therein as internal devices, a circuit breaker 5 provided along each of branch lines branched from main wires of a direct-current power supply, and a controller 6 for controlling switching of the breaker 5. The circuit breaker 5 comprises: power connecting terminals t1, t2 connected to the main wires; load connecting terminals t3, t4 connected with wires from a load; a semiconductor switch device 57 provided along an electrical circuit between the terminals t1, t2 and the terminals t3, t4; a current sensing resistor 56 for detecting an electric current through the electrical circuit; and a arithmetic circuit 60 for turning the device 57 on or off according to an on/off control signal from the controller 6, and coercively turning the device 57 off when a current value obtained from a voltage across the resistor 56 exceeds a set current.

Abstract: It comprises fixed terminal 42 provided with fixed contact 42a; movable armature 44 provided with movable contact 45; shaft 44 inserted in the movable armature; sealing container 40 holding the fixed terminal and housing the movable armature and the shaft therein in hermetically-sealed state; contact pressure spring 410 giving contact pressure between the movable contact and the fixed contact; return spring 411 urging the shaft to move away from the fixed contact; operation handle 1; shaft pressing piece 56 pressing, in accordance with the operation of the operation handle, the other end of main body of the shaft to move the shaft closer to the fixed contact; and electromagnetic tripping block 6 which makes the movable/fixed contacts open by taking the pressing means away from the other end of the main body of the shaft in case that anomalous current flows through the movable/fixed contacts when they are contacted.

Abstract: A system coordination unit 1 includes a reverse power flow prevention circuit 10. When power output from a fuel cell 6 and/or a secondary cell 7 exceeds power consumed in AC loads and DC loads, the reverse power flow prevention circuit 10 prevents a reverse flow of excess power into a commercial power source 4. The reverse power flow prevention circuit 10 is interposed in an AC main power path 20 between a connection point of a solar cell 5 and the AC main power path 20 and each of a connection point of a fuel cell 6 and the AC main power path 20 and a connection point of a secondary cell 7 and the AC main power path 20. The reverse power flow prevention circuit 10 compares the power output from the fuel cell 6 and/or the secondary cell 7 with the power consumed in the AC loads and the DC loads. Upon determining that the former power is not less than the latter power, the reverse power flow prevention circuit 10 electrically interrupts the AC main power path 20.

Abstract: The invention provides an electricity distribution system, which can keep a voltage to ground low, and can commonly detect abnormity, such as an electrical leak etc. produced in AC and DC feed lines. An AC-DC converter 21 is installed between the AC feed line (branch electrical circuit Lb) of a single phase three wire system for supplying the power to AC devices 41, and the DC feed line (main electrical circuit Ld) of a three wire system for supplying the power to DC devices. The DC feed line comprises a neutral wire N commonly connected to a neutral wire N of the AC feed line within the AC-DC converter 21, a positive voltage wire L+ having a positive electrical potential to an electrical potential of its neutral wire N, and a negative voltage wire L? having a negative electrical potential to the electrical potential of its neutral wire N. A voltage of +150 [V] is applied to the positive voltage wire L+, and a voltage of ?150 [V] is applied to the negative voltage wire L?.

Abstract: It comprises fixed terminal 42 provided with fixed contact 42a; movable armature 44 provided with movable contact 45; shaft 44 inserted in the movable armature; sealing container 40 holding the fixed terminal and housing the movable armature and the shaft therein in hermetically-sealed state; contact pressure spring 410 giving contact pressure between the movable contact and the fixed contact; return spring 411 urging the shaft to move away from the fixed contact; operation handle 1; shaft pressing piece 56 pressing, in accordance with the operation of the operation handle, the other end of main body of the shaft to move the shaft closer to the fixed contact; and electromagnetic tripping block 6 which makes the movable/fixed contacts open by taking the pressing means away from the other end of the main body of the shaft in case that anomalous current flows through the movable/fixed contacts when they are contacted.

Abstract: A DC distribution board comprises, therein as internal devices, a circuit breaker 5 provided along each of branch lines branched from main wires of a direct-current power supply, and a controller 6 for controlling switching of the breaker 5. The circuit breaker 5 comprises: power connecting terminals t1, t2 connected to the main wires; load connecting terminals t3, t4 connected with wires from a load; a semiconductor switch device 57 provided along an electrical circuit between the terminals t1, t2 and the terminals t3, t4; a current sensing resistor 56 for detecting an electric current through the electrical circuit; and a arithmetic circuit 60 for turning the device 57 on or off according to an on/off control signal from the controller 6, and coercively turning the device 57 off when a current value obtained from a voltage across the resistor 56 exceeds a set current.