Off-grid power distribution system

Abstract

To provide a power distribution system capable of surely performing leakage protection in an off-grid facility having its own power supply SOLUTION: An off-grid power distribution system comprising: a power distribution system for distributing power from a private power supply independent of a commercial power supply to an outlet in a structure separated from the commercial power supply; and a main breaker provided in the power distribution system, wherein the outlet comprises an outlet with an earth leakage breaker.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a power distribution system that supplies power from a private power source independent of a power grid to load devices (electrical devices) that consume the power. [Background technology]

[0002] An example of a structure that does not use a commercial power source is described in Patent Document 1. The structure is configured such that power generated by a solar power generation unit is charged into a power storage unit, and the power is converted into AC power by an inverter and supplied to electrical appliances (load devices) such as air conditioners and lighting equipment. The structure may also be a trailer house or a camper van. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Utility Model Registration No. 3230983 Summary of the Invention [Problem to be solved by the invention]

[0004] Even in trailer homes and other structures equipped with their own power sources, such as solar panels or storage batteries, they typically have their own internal power distribution system, just like regular homes and structures that draw in utility power. For example, the output of a high-voltage cutout switch connected to a solar panel or storage battery is routed to a distribution panel, which then connects the power outlets to the main breaker and downstream circuit breakers within the panel. While trailer homes and other structures are designed to be electrically insulated from people inside, high humidity or water leaks can reduce the resistance between people inside and the metal parts of the structure, increasing the likelihood of current flow between a person inside and the metal parts of the structure when they touch a load device powered by an outlet. In this case, if there is a ground fault within the structure and the fault is upstream of the main breaker (on the power source side), a difference will occur between the forward and return currents at the main breaker, causing the main breaker to trip and shut off the current. However, if the leakage point is downstream of the main breaker (towards the outlet), there is no difference between the forward and return current values ​​at the main breaker, and the main breaker cannot cut off the current.In other words, in off-grid structures such as trailer homes that are disconnected from commercial power and powered by their own power source, conventional general power distribution structures cannot completely cut off leakage or electric shock, leaving room for improvement in terms of safety.

[0005] The present invention has been made in light of the above technical problems, and aims to provide a power distribution system that can reliably provide earth leakage protection in off-grid facilities that have their own power sources. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides an off-grid power distribution system that has a power distribution system inside a structure that is separated from the commercial power source, which distributes power from a private power source independent of the commercial power source to an outlet, and a main breaker is provided in the distribution system, and the outlet is composed of an outlet equipped with a ground fault circuit interrupter. [Effects of the Invention]

[0007] According to the present invention, when a ground fault occurs upstream of the main breaker (on the private power source side), if the electrical resistance of the structure drops and electrical continuity occurs between the structure and an appropriate load device connected to an outlet, the main breaker will trip due to the current imbalance and cut off the current. Also, when a ground fault occurs downstream of the main breaker (on the outlet side), if electrical continuity occurs between the structure and an appropriate load device connected to the outlet, the main breaker will not trip, but the earth leakage breaker in the outlet will trip and cut off the current. Because the current can be cut off regardless of the location of the ground fault, it is possible to prevent electric shock and improve the electrical safety of the structure. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a circuit diagram for explaining an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] Next, an embodiment of the present invention will be described with reference to the accompanying drawings. Note that the embodiment described below is merely an example of how the present invention can be implemented, and is not intended to limit the present invention.

[0010] Figure 1 shows an off-grid trailer house (hereinafter simply referred to as trailer house) 1 as an example of an off-grid facility or structure that does not use commercial power. Trailer house 1 has rubber tires 2, and is therefore insulated from the ground. As its own power source, it is equipped with a secondary battery 3 and solar panels 4, which are installed outside trailer house 1, or inside as needed.

[0011] In Fig. 1, reference numeral 5 denotes a power conditioner, which includes a ZCT (zero-phase current transformer) 6 and a changeover switch 7. A secondary battery 3 is connected to the power conditioner 5 via a DC / DC converter 8. A solar panel 4 is also connected to the power conditioner 5. The housings of the power conditioner 5 and the solar panel 4 are electrically connected to a frame 9 of the trailer house 1.

[0012] The power distribution system inside the trailer house 1 is basically similar to conventionally known systems, with the output from the power conditioner 5 being supplied via a distribution board 10 to load devices (electrical appliances) 11 that consume power, such as lighting, air conditioners, and cooking appliances. The distribution board 10 is equipped with a changeover switch 12, a main breaker 13, and a sub-breaker 14. The changeover switch 12 is a switch for switching the power source for the trailer house 1 between the secondary battery 3 or solar panel 4 and a commercial power source 15. The main breaker 13 is a conventionally known earth leakage circuit breaker that operates when there is an imbalance between the forward and return current values, thereby interrupting the circuit.

[0013] The sub-breakers 14 are conventionally known circuit breakers that operate to interrupt the circuit when a current greater than a set current flows. The switch 12, main breaker 13, and sub-breakers 14 are connected in the order shown here, and a receptacle 16 for connecting a load device 11 is connected to the sub-breakers 14 by a predetermined wiring. The receptacle 16 is a receptacle equipped with an Earth Leakage Circuit Breaker (ELCB) 17.

[0014] Regarding the grid-connected operation option for using commercial power supply 15, a terminal box (TB) 18 for connecting commercial power supply 15 is attached to the exterior of trailer house 1. Distribution board 10 is provided with a service breaker (SB) 19 interposed between terminal box 18 and switch 12. Furthermore, a circuit is provided that connects the output side of this service breaker 19 to changeover switch 7 in power conditioner 5 described above, and a linkage breaker 20 and a power generation parallel-off breaker 21 are connected in series to this circuit. Note that these linkage breaker 20 and power generation parallel-off breaker 21 are provided inside distribution board 10. Furthermore, the housings of distribution board 10, terminal box 18, etc. are electrically connected to frame 9 of trailer house 1.

[0015] Next, we will explain the earth leakage protection provided by the above-mentioned power distribution system. In Figure 1, the earth leakage points in the interior wiring of the trailer house 1 are indicated by the symbols A and B. Earth leakage point A is upstream of the main breaker 13 (on the power supply side), and earth leakage point B is downstream of the main breaker 13 (on the sub-breaker 14 side) and upstream of the sub-breaker 14 (on the main breaker 13 side).

[0016] The living space of the trailer house 1 is covered with electrically insulating floor panels and wall materials. However, when the humidity is high or when the living space is wet due to spilled water, the resistance between the inner surface of the living space and the frame 9 decreases. In such a case, if a current leak occurs in the load device 11 and a person 22 touches the load device 11, a circuit is established between the load device 11 and the frame 9, causing electrical continuity.

[0017] In this case, if there is a leakage current at leakage point A upstream of main breaker 13, part of the return current at main breaker 13 will flow from leakage point A through frame 9, causing an imbalance between the forward and return current values ​​at main breaker 13. This will cause main breaker 13 to operate and break the circuit. In this case, leakage point A is also upstream of earth leakage breaker 17 installed in outlet 16, so an imbalance between the forward and return current values ​​will also occur at earth leakage breaker 17, which may result in earth leakage breaker 17 breaking the circuit. The priority order of the interruption operations of main breaker 13 and earth leakage breaker 17 can be determined as appropriate by changing their respective setting values.

[0018] In contrast, if there is a leak at leakage point B between main breaker 13 and slave breaker 14, the leakage occurs downstream of main breaker 13, so there is no imbalance between the forward and return current values, and main breaker 13 does not operate to break the circuit. On the other hand, since the leakage occurs upstream of earth leakage breaker 17 installed in outlet 16, there is an imbalance between the forward and return current values ​​at earth leakage breaker 17, and as a result, earth leakage breaker 17 operates and breaks the circuit.

[0019] Therefore, according to the power distribution system of the embodiment of the present invention described above, even if a leakage current occurs at any point in the wiring inside the vehicle, either the main breaker 13 or the earth leakage breaker 17 of the outlet 16 will operate to cut off the circuit, thereby reliably preventing or minimizing electric shock to a person 22 who touches the load equipment 11.

[0020] The present invention is not limited to the above-described embodiments, and the off-grid structures or facilities to which the present invention can be applied may be, in addition to trailer houses, structures installed in arid regions such as deserts where commercial power cannot be used or in polar regions, artificial satellites, and vehicles for planetary exploration such as on the moon or Mars. [Explanation of symbols]

[0021] 1 Trailer house 2 tires 3 Secondary battery 4. Solar panels 5 Power conditioner 6 ZCT (Zero phase current transformer) 7. Selector switch 8 DC / DC converters 9 frames 10 Distribution board 11 Load equipment 12 Switch 13 Main breaker 14 Sub-breaker 15 Commercial power supply 16 power outlets 17 Earth leakage breaker 18 Terminal box 19 Service breaker 20 Interlocking breaker 21 Power generation parallel-off breaker 22 Humans A, B Leakage point

Claims

[Claim 1] An off-grid power distribution system having a power distribution system that distributes power from a private power source independent of the commercial power source to an outlet inside a structure that is separated from the commercial power source, and a main breaker is provided in the power distribution system, An off-grid power distribution system, characterized in that the outlet is configured as an outlet equipped with a ground fault circuit interrupter.

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