JP2007295754A - Power distribution system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power distribution system that is capable of inexpensively preventing the occurrence of an unbalanced current while performing power distribution to a large number of loads. <P>SOLUTION: The power distribution system inputs three-phase four-wire system AC power into a distribution board 3 through a trunk line 2 so as to perform power distribution to a plurality of single-phase loads 4 from the distribution board 3. The power distribution system is composed as follows. A power supply switch 33, which simultaneously cuts off a wiring of each phase in three-phase four wires, is provided in the distribution board. Output lines 5 of the three-phase four-wire system are connected to the output side of the power supply switch 33. Each of a plurality of the single-phase loads 4 is respectively connected to each wiring of the output lines 5. The power supply switch 33 simultaneously cuts off the wiring of each phase of the three-phase four-wire system. Therefore, it is possible to prevent the unbalanced current from flowing in the trunk line 2 and output lines 5 of the three-phase four-wire system, and also, possible to use thin wirings as the wirings constituting the trunk line 2 and output lines 5. Consequently, it is possible to reduce wiring costs. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power distribution system that distributes a three-phase four-wire AC power source to a plurality of loads.

Conventionally, as a power distribution system that distributes a three-phase four-wire AC power source to a plurality of loads, as described in Japanese Patent Laid-Open No. 11-32437, it is input to a three-phase four-wire AC voltage distribution board. A distribution system that distributes power from a distribution board to a plurality of single-phase loads is known. In this power distribution system, when an unbalanced current is generated by an unbalanced load, voltage distribution is maintained by a distribution transformer provided between the load and the distribution board.
Japanese Patent Laid-Open No. 11-32437

  However, in the power distribution system, when there are a large number of loads on the output side of the distribution board, a large number of distribution transformers are required accordingly, and the installation cost of the system becomes high. Also, when a large number of loads are connected to the output side of the distribution board, if there is no distribution transformer, it is necessary to use a highly rated wiring for the output wiring so that it can withstand the generation of unbalanced current . At that time, in the case of power distribution in a large facility where the wiring distance becomes long, the cost of wiring becomes large.

  Accordingly, the present invention has been made to solve such a technical problem, and an object thereof is to provide a power distribution system capable of preventing generation of an unbalanced current at low cost while performing power distribution to a large number of loads. To do.

  That is, the distribution system according to the present invention is a distribution system in which three-phase four-wire AC power is input to a distribution board through a trunk line, and distribution is performed from the distribution panel to a plurality of single-phase loads. A circuit blocking means for simultaneously blocking the wiring of each phase in the three-phase four-wire, a three-phase four-wire output wiring connected to the output side of the circuit blocking means, and the output wiring. And a branching device for branching the three-phase four-wire output wiring to the single-phase two-wire second output wiring connected to the single-phase load.

  According to the present invention, by providing the circuit interrupting means for simultaneously interrupting the wiring of each phase in the three-phase four-wire, the wiring of each phase is simultaneously interrupted when the three-phase four-wire wiring circuit is interrupted. For this reason, it is possible to prevent an unbalanced current from flowing through the three-phase four-wire main line and the output wiring. Therefore, a thin wire can be used as the wiring constituting the three-phase four-wire main line and the output wiring, and the wiring cost can be reduced.

  Moreover, in the power distribution system according to the present invention, it is preferable that the circuit interrupting means is a circuit breaker that interrupts the power distribution circuit when a predetermined current or more flows through the single-phase load.

  According to the present invention, by providing a circuit breaker that interrupts the power distribution circuit when an overcurrent flows through a single-phase load, the wiring of each phase is simultaneously interrupted when an overcurrent flows through the single-phase load. . Therefore, it is possible to prevent an unbalanced current from flowing through the three-phase four-wire main line and the output wiring. Therefore, a thin wire can be used as the wiring constituting the three-phase four-wire main line and the output wiring, and the wiring cost can be reduced.

  In the power distribution system according to the present invention, it is preferable that the circuit breaker is a switch that can arbitrarily open and close the wiring of each phase in the three-phase four-wire system.

  According to the present invention, it is possible to arbitrarily turn on / off a single-phase load by providing a switch that can arbitrarily open and close the wiring of each phase in the three-phase four-wire system. In this case, since the wirings of the respective phases are simultaneously opened and closed, it is possible to prevent an unbalanced current from flowing through the three-phase four-wire main line and the output wiring.

  Further, in the power distribution system according to the present invention, the circuit breaker may arbitrarily connect a circuit breaker that breaks the power distribution circuit when a current exceeding a predetermined value flows through the single-phase load and a wiring for each phase in the three-phase four-wire system. It is preferable to provide a switch that can be opened and closed.

  According to the present invention, by providing a circuit breaker that shuts off the power distribution circuit when an overcurrent flows through the single-phase load and a switch that can arbitrarily open and close the wiring of each phase in the three-phase four-wire system, When an overcurrent flows through the phase load or when the wiring circuit is interrupted by the switch, the wiring of each phase of the three-phase four-wire system is simultaneously interrupted. For this reason, in any case, it is possible to prevent an unbalanced current from flowing through the three-phase four-wire main line and the output wiring. Therefore, a thin wire can be used as the wiring constituting the three-phase four-wire main line and the output wiring, and the wiring cost can be reduced.

  In the power distribution system according to the present invention, it is preferable that a circuit breaker and a switch are not provided on the output side of the circuit breaker.

  According to this invention, since the circuit breaker and the switch are not provided on the output side of the circuit breaker, it is possible to prevent an unbalanced current from being generated in the output wiring due to the operation of the circuit breaker and the switch.

  In the power distribution system according to the present invention, it is preferable that the single-phase load is not provided with a switch for turning on / off the operation thereof.

  According to the present invention, by using a single-phase load that does not include a switch for turning on / off the operation, it is possible to prevent an unbalanced current from being generated in the output wiring due to the on / off of the operation switch.

  Moreover, the power distribution system which concerns on this invention WHEREIN: It is preferable that the said single phase type load is a lighting fixture installed in a store.

  According to the present invention, the load is mainly used while being turned on and off at the same time, so that it is optimal as a power distribution object of the power distribution system of the present application.

  According to the present invention, it is possible to prevent generation of an unbalanced current at low cost while distributing power to a large number of loads.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a schematic circuit diagram of a power distribution system according to an embodiment of the present invention.

  As shown in FIG. 1, the power distribution system according to the present embodiment inputs three-phase four-wire AC power supplied from a low-voltage switchboard 1 to a distribution board 3, and the plurality of single-phases from the distribution board 3. In this system, power is distributed to the load 4 of the equation. The low-voltage switchboard 1 is power supply means for supplying three-phase four-wire AC power, and includes a breaker 11 that cuts off wiring due to overcurrent. A trunk line 2 is connected to the output side of the low voltage switchboard 1. The trunk line 2 is a wiring for transmitting the three-phase four-wire AC power supplied from the low-voltage switchboard 1 to the distribution board 3. The three-phase four-wire R-phase, S-phase, T-phase, and N-phase It consists of two wires.

  The distribution board 3 divides and distributes three-phase four-wire AC power into a plurality of output systems, and a plurality of three-phase four-wire output wirings 5 are connected to the output side. The distribution board 3 includes, for example, a first wiring 31 and a second wiring 32. The first wiring 31 and the second wiring 32 are three-phase four-wire wirings, and are composed of four wirings of R phase, S phase, T phase, and N phase. The trunk line 2 is connected to the first wiring 31, and a plurality of second wirings 32 are branched from the first wiring 31. In FIG. 1, one second wiring 32 is shown connected to the first wiring 31, but for convenience of explanation, the other second wiring 32 is not shown. A plurality of output wires 5 are connected so as to branch from the second wire 32.

  As described above, in the distribution board 3, the main line 2, the first wiring 31, the second wiring 32, and the output wiring 5 are sequentially branched, so that one main line 2 can be branched into a large number of output wirings 5. it can.

  The distribution board 3 is provided with a power switch 33 and a breaker 34. The power switch 33 is a switch for turning on and off the load 4 connected to the output side of the output wiring 5 and can be arbitrarily opened and closed manually or the like. The power switch 33 functions as a circuit shut-off means for simultaneously shutting off the wiring of each phase in the three-phase four-wire system in the distribution board 3. The power switch 33 is provided between the first wiring 31 and the second wiring 32, for example, and simultaneously opens and closes the wiring of each phase in the three-phase four-wire system transmitted to the second wiring 32.

  The breaker 34 functions as a circuit breaker that interrupts the wiring circuit when a predetermined current or more flows through the load 4, and is installed in the output wiring 5, for example. The output wiring 5 is a three-phase four-wire wiring, and is composed of four wirings of R phase, S phase, T phase, and N phase. One breaker 34 is provided for each output wiring 5, and when an overcurrent of a predetermined current or more flows through any of the loads 4 connected to the output wiring 5, the wiring of each phase of the output wiring 5 At the same time.

  A branching device 6 is connected to the output side of the output wiring 5. The branching device 6 branches the three-phase four-wire output wiring 5 to the single-phase two-wire second output wiring 7. The output wiring 5 inputted to the branching device 6 is branched to a single-phase two-wire second output wiring 7 composed of three combinations of R phase and N phase, S phase and N phase, T phase and N phase. A load 4 is connected to each second output wiring 7. The load 4 is an electric device that operates by, for example, single-phase two-wire power.

  The load 4 is preferably one that does not include a switch for turning off or off the operation. For example, the load 4 corresponds to a lighting fixture such as a fluorescent lamp. By using a load 4 that does not include a switch for turning off / off the operation of a lighting fixture or the like, it is possible to prevent an unbalanced current from being generated in the output wiring 5 due to the switch on / off.

  In this power distribution system, no other circuit breaker and switch are provided on the output side of the breaker 34 that blocks the output wiring of the three-phase four-wire. For this reason, the circuit breaker and the switch are not operated on the output side of the breaker 34, and an unbalanced current is not generated in the output wiring 5.

  Next, the operation of the power distribution system according to this embodiment will be described.

  In FIG. 1, three-phase four-wire AC power is transmitted from a low voltage switchboard 1 through a trunk line 2 and input to a distribution board 3. This AC power is input to the three-phase four-wire first wiring 31 in the distribution board 3. At this time, when the power switch 33 is on and in a conductive state, the AC power is transmitted to the second wiring 32 through the power switch 33.

  Then, the AC power is transmitted to the branching device 6 through the breaker 34 and the output wiring 5. The AC power is branched from the three-phase four-wire output wiring 5 to the single-phase two-wire second output wiring 7 and distributed to the load 4.

  As described above, when the power switch 33 is turned off in a state where the AC power is supplied to the load 4, the power supply to the load 4 installed on the output side of the power switch 33 is stopped. At this time, the wiring of each phase in the three-phase four-wire in the distribution board 3 is cut off simultaneously by the off operation of the power switch 33. For this reason, an unbalanced current is prevented from flowing through the three-phase four-wire main line 2 and the output wiring 5 due to the off operation of the power switch 33, and the amount of voltage drop in power distribution is reduced. Accordingly, thin wirings constituting the three-phase four-wire main line 2 and the output wiring 5 can be used, and the wiring cost in the power distribution system can be reduced.

  Further, in the state where AC power is supplied to the load 4, when an overcurrent exceeding a predetermined current flows through the load 4 due to electric leakage or the like, the breaker 34 is cut off, the output wiring 5 is cut off, and the breaker 34 The power supply to the load 4 installed on the output side is stopped. At this time, due to the breaking operation of the breaker 34, the wiring of each phase in the three-phase four-wire in the distribution board 3 is simultaneously cut off. For this reason, an unbalanced current is prevented from flowing through the three-phase four-wire trunk line 2 and the output wiring 5 by the breaking operation of the breaker 34, and the amount of voltage drop in distribution is reduced. Accordingly, thin wirings constituting the three-phase four-wire main line 2 and the output wiring 5 can be used, and the wiring cost in the power distribution system can be reduced.

  Next, cost reduction of the power distribution system according to the present embodiment will be described in detail.

  2 and 3 are schematic circuit diagrams of a comparative example of the power distribution system. FIG. 2 shows a first comparative example of a power distribution system that distributes single-phase three-wire AC power to a plurality of single-phase loads. FIG. 3 shows a second comparative example of a power distribution system that distributes three-phase four-wire AC power to a plurality of single-phase loads.

  As shown in FIG. 2, the power distribution system of the first comparative example inputs single-phase three-wire AC power to the distribution board 102 through the main line 101. The main line 101 is provided with a circuit breaker 103 that interrupts the circuit when an overcurrent occurs. In the distribution board 102, single-phase two-wire output wirings 104 and 105 are drawn from single-phase three-wire wiring. Power is transmitted to the load 106 by the output wiring 104. The load 106 is, for example, a 200V lighting fixture. Power is transmitted to the load 107 by the output wiring 105. The load 107 is, for example, a 100V outlet. The output wiring 105 is provided with a breaker 108 that blocks the output wiring 105 due to overcurrent.

  As shown in FIG. 3, the power distribution system of the second comparative example inputs three-phase four-wire AC power to the distribution board 202 through the main line 201. The main line 201 is provided with a breaker 203 that cuts off the circuit when an overcurrent occurs. In the distribution board 202, single-phase two-wire output wirings 204 and 205 are drawn from three-phase four-wire wiring. Power is transmitted to the load 206 by the output wiring 204. The load 206 is, for example, a 100V lighting fixture. Power is transmitted to the load 207 by the output wiring 205. The load 107 is, for example, a 100V outlet. The output wiring 204 is provided with a breaker 208 that interrupts the output wiring 204 due to overcurrent, and the output wiring 205 is provided with a breaker 209 that interrupts the output wiring 205 due to overcurrent.

  In the first comparative example of FIG. 2 and the second comparative example of FIG. 3, it is necessary to use the main cables 101 and 201 having a large cable size, resulting in high wiring costs. That is, when an overcurrent flows through the load 107 or the load 207, the output wirings 105 and 205 are interrupted by the operation of the breaker 108 or the breaker 208. At this time, an unbalanced current flows through the main lines 101 and 201, and it is necessary to use a high rated current as a wiring cable for the main lines 101 and 102, resulting in an increase in wiring cost.

  In contrast, in the power distribution system according to the present embodiment of FIG. 1, when an overcurrent flows through the load 4, the output wiring 5 is interrupted by the operation of the breaker 34. At this time, since all the three-phase four-wire output wirings 5 are simultaneously cut off, an unbalanced current does not flow through the output wiring 5. At that time, no unbalanced current flows through the main line 2. Furthermore, since no breaker is installed for each load 4, an unbalanced current does not flow through the output wiring 5 due to the operation of the breaker for each load 4. As described above, according to the wiring system according to the present embodiment, since an unbalanced current is prevented, an inexpensive cable having a low rated current can be used as the main line 2 and the output wiring 5. Can be lowered.

As a specific wiring cost, for example, when power is distributed to a large number of lighting fixtures in a commercial facility of about 60,000 m ² , the power distribution system according to this embodiment has a wiring cost of about 20% compared to the first comparative example. Reduction can be achieved. In addition, the power distribution system according to this embodiment can reduce the wiring cost by about 35% compared to the second comparative example.

  As described above, according to the power distribution system according to the present embodiment, it is possible to prevent generation of an unbalanced current at a low cost while performing power distribution to a large number of loads 4. That is, by providing the breaker 34 and the switch 33 that simultaneously cut off the wiring of each phase in the three-phase four-wire, the wiring of each phase is cut off at the same time when the three-phase four-wire wiring circuit is cut off. For this reason, it is possible to prevent an unbalanced current from flowing through the three-phase four-wire main line 2 and the output wiring 5, and thin lines are used as the three-phase four-wire main line 2 and the output wiring 5. be able to. Therefore, the wiring cost can be reduced.

  For example, when an overcurrent flows through the load 4, the wiring of each phase of the output wiring 5 is simultaneously cut off by the breaker 34. For this reason, it is possible to prevent an unbalanced current from flowing through the three-phase four-wire main line 2 and the output wiring 5. Further, when the switch 33 is closed and the power supply of the load 4 is turned off, the wiring of each phase of the three-phase four-wire is simultaneously cut off by the switch 33. For this reason, it is possible to prevent an unbalanced current from flowing through the three-phase four-wire main line 2 and the output wiring 5.

  Further, according to the power distribution system according to the present embodiment, since the circuit breaker and the switch are not provided on the output side of the breaker 34, an unbalanced current is generated in the output wiring by the operation of the circuit breaker and the switch. Can be prevented.

  In addition, according to the power distribution system according to the present embodiment, the output wiring 5 is unbalanced by turning on / off the operation switch by using a lighting device that does not include a switch for turning on / off the operation as the single-phase load 4. Generation of current can be prevented.

  This power distribution system according to the present embodiment is useful when the single-phase load 4 is a facility lighting fixture. In particular, it is optimal when the load 4 is a lighting fixture in which a store is installed. In this case, since the lighting fixtures are mainly turned on and off at the same time, the power distribution system according to the present embodiment can be easily applied, and the power distribution system can be constructed at low cost.

  In addition, this embodiment shows one embodiment of the power distribution system according to the present invention, and the power distribution system according to the present invention is not limited to the above, and the invention described in each claim. The power distribution system according to the embodiment may be modified and applied to other things without changing the gist of the above.

  For example, in the above-described embodiment, the case where both the switch 33 and the breaker 34 are installed in the power distribution system has been described. However, only one of the switch 33 or the breaker 34 may be installed. Even in this case, generation of an unbalanced current can be prevented during the operation of the switch 33 or the breaker 34.

1 is a circuit schematic diagram of a power distribution system according to an embodiment of the present invention. It is a circuit schematic diagram which shows the 1st comparative example of a power distribution system. It is a circuit schematic diagram which shows the 2nd comparative example of a power distribution system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Low voltage switchboard 2 ... Trunk line 3 ... Distribution board 4 ... Load 5 ... Output wiring 6 ... Branching device 7 ... Second output wiring 11 ... Breaker 31 ... First wiring 32 ... Second wiring 33 ... Power switch 34 ... Breaker

Claims (7)

In a distribution system that inputs three-phase four-wire AC power to the distribution board through the trunk line and distributes power from the distribution panel to multiple single-phase loads,
A circuit interrupting means provided in the distribution board for simultaneously disconnecting the wiring of each phase in the three-phase four-wire;
A three-phase four-wire output wiring connected to the output side of the circuit interrupting means;
A branching device connected to the output wiring and for branching a three-phase four-wire output wiring to a single-phase two-wire second output wiring connected to the single-phase load;
A power distribution system characterized by comprising:   2. The power distribution system according to claim 1, wherein the circuit interrupting unit is a circuit breaker that interrupts the power distribution circuit when a predetermined current or more flows through the single-phase load.   The power distribution system according to claim 1, wherein the circuit breaker is a switch that can arbitrarily open and close the wiring of each phase in a three-phase four-wire system. The circuit interrupting means includes a circuit breaker that interrupts the power distribution circuit when a current more than a predetermined value flows through the single-phase load and a switch that can arbitrarily open and close the wiring of each phase in the three-phase four-wire system. ,
The power distribution system according to claim 1.   The power distribution system according to any one of claims 1 to 4, wherein a circuit breaker and a switch are not provided on an output side of the circuit breaker.   The power distribution system according to any one of claims 1 to 5, wherein the single-phase load is not provided with a switch for turning on and off its operation. The power distribution system according to claim 1, wherein the single-phase load is a lighting device installed in a store.

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