Power line communication system and cubicle

Abstract

To provide a power line communication system and a cubicle, capable pf securing appropriate communication quality in narrow band power line communication.SOLUTION: A facility system 101 includes a power line communication system 100 comprising: an origination unit 6 that is electrically connected to a transformer 31 for changing voltage, using a cable way W6 and a cable way W7 and originates a signal in narrow band power line communication; a reception unit 4 that is electrically connected to the origination unit and receives the signal; and a promotion unit 33 that is provided directly under the transformer 31 on the cable way W6 and promotes a flow of the signal from the origination unit 6 to the reception unit 4.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a power line communication system and a cubicle. [Background technology]

[0002] Power line communication (PLC (Power Line Communication)), which transmits signals by superimposing them on power lines, has been known for some time. Patent Document 1 discloses a power line communication device that is connected to a power line and is composed of one or more communication devices that are capable of communicating via the power line. Patent Document 1 also discloses a printer main body that is connected to a power line and performs power line communication, and a PC main body that performs power line communication with the printer main body via the power line. The printer main body is connected to a power line communication unit that performs power line communication with the PC main body, and transmits and receives signals to and from the power line communication unit via a control line. The PC main body is equipped with a PCI board. The power line communication unit and the PCI board each have a driver receiver that transmits and receives power line communication signals. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-165950 Summary of the Invention [Problem to be solved by the invention]

[0004] In power line communications, when a signal is transmitted from a signal transmitter to a signal receiver, some of the signal may be transmitted from the transmitter to the power supply side opposite the receiver, making it difficult for the signal to be transmitted from the transmitter to the receiver. For example, in the configuration of Patent Document 1, there is a risk that a signal output from a PC to a printer may not be properly transmitted to the printer. In this case, the signal from the transmitter has difficulty reaching the receiver, making it impossible to ensure proper communication quality.

[0005] An object of the present disclosure is to provide a power line communication system and a cubicle that can ensure appropriate communication quality in narrowband power line communication. [Means for solving the problem]

[0006] A power line communication system according to one aspect of the present disclosure includes a transmitter electrically connected to a voltage-changing transformer by a first electrical circuit and transmitting a signal in narrowband power line communication, a receiver electrically connected to the transmitter and receiving the signal, and a promotion unit provided directly below the transformer on the first electrical circuit and promoting the flow of the signal from the transmitter to the receiver.

[0007] In this power line communication system, the transformer and the transmitter are electrically connected, and the transmitter and the receiver are electrically connected. The facilitating unit is provided directly below the transformer, and therefore can facilitate the flow of signals from the transmitter to the receiver in the first electrical path upstream of the transmitter. This allows the receiver to properly acquire signals from the transmitter. Therefore, this power line communication system can ensure appropriate communication quality.

[0008] In one embodiment of a power line communication system, the receiving unit may be electrically connected to the transmitting unit via a second electrical circuit, and the promoting unit may adjust the impedance of the first electrical circuit to be greater than the impedance of the second electrical circuit. In this case, the promoting unit adjusts the impedance of the first electrical circuit to be greater than the impedance of the second electrical circuit, making it easier for signals from the transmitting unit to flow through the second electrical circuit than through the first electrical circuit. Therefore, the promoting unit can promote the flow of signals from the transmitting unit to the receiving unit, ensuring appropriate communication quality.

[0009] A power line communication system according to one embodiment may further include a distribution board that houses a main breaker that is provided on a first electrical circuit between the transformer and the transmitter, and the facilitating unit may be provided outside the distribution board on the first electrical circuit between the transformer and the distribution board. In this case, the facilitating unit is installed outside the distribution board directly below the transformer. This power line communication system reduces the man-hours required to install a facilitating unit for each distribution board and can simultaneously promote the flow of signals to each distribution board.

[0010] In the power line communication system according to one embodiment, the frequency of the signal may be equal to or greater than 10 kHz and equal to or less than 450 kHz.

[0011] In one embodiment of the power line communication system, the facilitating unit may be provided in at least one of the three-phase first electric circuits. In this case, for example, if the facilitating unit is provided in the electric circuit to which at least the transmitting unit and the receiving unit are connected, it can promote the flow of signals. Therefore, this power line communication system can minimize the number of facilitating units installed, and facilitate the installation and maintenance of the facilitating units.

[0012] According to another aspect of the present disclosure, there is provided a cubicle connected to a power line communication system including a transmitter for transmitting a signal in narrowband power line communication and a receiver for receiving the signal, the cubicle including: a transformer electrically connected to the power line communication system by a first electric path and adapted to change voltage; and a promoting unit provided directly below the transformer and promoting signal flow to the opposite side of the transformer.

[0013] In this cubicle, the transformer and the power line communication system are electrically connected by a first electrical path. The accelerating unit is provided directly below the transformer, and therefore can accelerate the flow of signals from the transmitting unit to the receiving unit in the cubicle upstream of the transmitting unit. This allows the receiving unit to properly acquire signals from the transmitting unit. Therefore, this cubicle can ensure appropriate communication quality. Furthermore, for example, there is no need to provide an accelerating unit for each distribution board connected to the cubicle. The accelerating unit provided in the cubicle can collectively accelerate the flow of signals in the electrical paths downstream of the cubicle.

[0014] In one embodiment of the cubicle, the cubicle may have a plurality of breakers electrically connected to the transformer by a first electric circuit and provided between the transformer and the transmitting unit, and the facilitating unit may be provided between the transformer and the breaker. In this case, compared to installing and maintaining the facilitating unit downstream of each breaker, installing the facilitating unit between the transformer and the breaker can reduce the labor required to install and maintain the facilitating unit. [Effects of the Invention]

[0015] According to the power line communication system and cubicle of the present disclosure, appropriate communication quality can be ensured in narrowband power line communication. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram illustrating a power line communication system according to an embodiment. [Figure 2] FIG. 2(a) is a block diagram of the detection slave unit, FIG. 2(b) is a block diagram of the receiving unit, and FIG. 2(c) is a block diagram of the transmitting unit. [Figure 3] 1 is a schematic configuration diagram illustrating an example of a power line communication system and a cubicle according to an embodiment. [Figure 4] FIG. 2 is a schematic diagram illustrating the configuration of a distribution board. [Figure 5]FIG. 1 is a schematic diagram illustrating a configuration of a cubicle according to an embodiment. [Figure 6] FIG. 10 is a schematic diagram showing the configuration of a cubicle according to a modified example. [Figure 7] FIG. 10 is a schematic configuration diagram showing a power line communication system according to a modified example. [Figure 8] Fig. 8(a) is a circuit diagram of a power line communication system according to a comparative example before a transformer and a facilitating unit are installed, and Fig. 8(b) is a graph of experimental results showing a signal spectrum at a receiving unit before a transformer and a facilitating unit are installed. [Figure 9] 9A is a circuit diagram of a power line communication system according to a comparative example after a transformer is installed but before a facilitating unit is installed, and FIG. 9B is a graph of experimental results showing a signal spectrum at a receiving unit after a transformer is installed but before a facilitating unit is installed. [Figure 10] 10A is a circuit diagram of the power line communication system according to the embodiment after the transformer and the acceleration unit are installed, and FIG. 10B is a graph of experimental results showing the signal spectrum at the receiving unit after the transformer and the acceleration unit are installed. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the following description, identical or equivalent elements will be designated by the same reference numerals, and redundant description will not be repeated. The dimensional ratios of the drawings do not necessarily match those in the description. The terms "upper," "lower," "left," and "right" are based on the illustrated state and are for convenience only.

[0018] FIG. 1 is a block diagram showing a power line communication system 100 according to an embodiment of the present invention. As shown in FIG. 1, the power line communication system 100 is a system that transmits information between devices using power line communication (PLC), which transmits signals by superimposing them on a power line. Power line communication is a communication method that transmits and receives communication signals using a power line, for example, by superimposing a communication signal of a frequency different from the commercial frequency on a power waveform of the commercial frequency and transmitting the signal, and then separating the communication signal of the different frequency from the power waveform and receiving it. Note that power line communication may be subject to the Radio Law depending on the frequency band. However, the power line communication system 100 according to this embodiment is a system that can perform narrowband power line communication (low-speed PLC), which transmits signals in a frequency band of 10 kHz to 450 kHz by superimposing them on a power line. The power line communication system 100 uses narrowband power line communication so that it can be used both indoors and outdoors and can transfer data at a certain level. Hereinafter, signals transmitted through narrowband power line communication will be simply referred to as signals. Furthermore, when narrowband power line communication is used, the modulation method is not particularly limited, and either the OFDM method or the DCSK method may be adopted.

[0019] The power line communication system 100 includes a detector 1, a detection slave unit 2, a controlled facility 3, a receiving unit 4, and a transmitting unit 6. For example, the power line communication system 100 may be applied to a building BD1 having multiple floors F1 to F3 (see FIG. 3).

[0020] In the power line communication system 100, the detector 1 and the detector slave unit 2 are connected by a wiring W1. The detector slave unit 2 and the transmitter unit 6 are connected by a power line W2. The controlled equipment 3 and the receiver unit 4 are connected by a wiring W3. The receiver unit 4 and the transmitter unit 6 are connected by a power line W4. The main purpose of the power line is to supply AC power at commercial frequencies, and it serves as a transmission path for power line communication. Specifically, power line communication takes place between the detector slave unit 2 and the receiver unit 4 and the transmitter unit 6. Power line communication takes place between the detector 1 and the detector slave unit 2, and between the controlled equipment 3 and the receiver unit 4. In power line communication, communication signals can not only be superimposed on AC power distribution such as AC 100V or AC 200V, but also on DC power distribution in the same way as on AC. When the detector 1 is, for example, a motion sensor or an illuminance meter, the signal from the detector 1 may first pass through the transmitter 6 and then be transmitted over power lines to the receiver 4 at the discretion of the transmitter 6. However, depending on the program of the transmitter 6, the detector slave 2 may also be able to send and receive commands to the receiver 4 using power line communication without passing through the transmitter 6.

[0021] The detector 1 is a device that detects various types of information and is composed of measuring instruments, sensors, etc. Examples of detectors that can be used include a motion sensor that detects the presence of a person, a light meter that detects the brightness of a room, and an ammeter that detects a current value. The detector 1 outputs the detected information to the detection slave unit 2 via a wiring W1. The detector 1 is not limited to the above-mentioned devices, and other measuring instruments and sensors may also be used. For example, a measuring instrument that monitors the amount of power generated by renewable energy sources such as solar cells may also be used as the detector 1. Furthermore, the detector 1 may be a battery remaining capacity data output unit installed in a power controller of a fixed storage battery or an on-board storage battery. Furthermore, the detector 1 may also be a carbon dioxide detector, a carbon monoxide detector, a dust detector, etc.

[0022] The detector slave 2 is a slave provided for the detector 1. The detector slave 2 converts detection information received from the detector 1 into a power line communication signal and outputs it to the transmitter 6 via the power line W2. The detector slave 2 is provided in a one-to-one correspondence with each detector 1. For example, if there are multiple detectors 1 on a floor, one detector slave 2 is provided for each detector 1. For example, a dedicated detector slave 2 is provided for an ammeter, a dedicated detector slave 2 is provided for a motion sensor, and a dedicated detector slave 2 is provided for a illuminance meter. If there are multiple motion sensors, one dedicated detector slave 2 is provided for each motion sensor. The detector slave 2 is provided in a position close to the target detector 1. The detector slave 2 is provided on the power line connected to the target detector 1, so that a physical one-to-one correspondence is established between the detector 1 and the target detector 1. The detector slave 2 and the detector 1 may be constructed as a single device. In this case, one device has a unit that functions as a detection slave unit 2 and a unit that functions as a detector 1. The two are connected by a wiring W1 within the device. The wiring W1 that connects the detector 1 and the detection slave unit 2 is composed of a signal line. The detection slave units 2 and the detector 1 do not necessarily have to be in a one-to-one relationship; for example, a configuration in which information is transmitted from multiple detectors 1 to one detection slave unit 2 may be adopted.

[0023] With reference to FIG. 2(a), a detailed block configuration of the detection slave unit 2 will be described. FIG. 2(a) is a block configuration diagram of the detection slave unit. The detection slave unit 2 includes a communication unit 11, a processing unit 12, and a memory unit 13. The communication unit 11 is a unit that communicates with the transmission unit 6 and the detector 1. The communication unit 11 has a circuit that receives detection information from the detector 1. The communication unit 11 also has a circuit that converts the detection information from the detector 1 into a power line communication signal for the transmission unit 6. The processing unit 12 is a unit that controls the operation of the entire detection slave unit 2. The processing unit 12 is configured to include a microprocessor, its peripheral circuits, etc.

[0024] The storage unit 13 is a unit that stores programs and information necessary for the operation of the detection slave unit 2. The storage unit 13 includes a nonvolatile storage element such as a ROM (Read Only Memory), a rewritable nonvolatile storage element such as an EEPROM (Electrically Erasable Programmable Read Only Memory), and a volatile storage element such as a RAM (Random Access Memory) that serves as a working memory. For example, the storage unit 13 stores an address indicating the position of the detection slave unit 2 within the building BD1.

[0025] The controlled facility 3 shown in FIG. 1 is a facility that is subject to control by the power line communication system 100. Examples of the controlled facility 3 include lighting (such as LED lighting) that can adjust the illuminance in a room, air conditioning that adjusts the temperature in a room, and a storage battery that adjusts the discharge and charge. The controlled facility 3 receives control information from the receiver 4 via wiring W3. Note that the controlled facility 3 is not limited to the above-mentioned devices, and other facilities may also be used.

[0026] The receiver 4 is a slave unit provided for the controlled equipment 3. The receiver 4 is electrically connected to the transmitter 6 and receives signals. The receiver 4 converts the control information received from the transmitter 6 via the power line communication signal into a signal that can be processed by the controlled equipment 3 and outputs the signal to the controlled equipment 3 via the wiring W3. The receiver 4 is provided in a one-to-one correspondence with each controlled equipment 3. For example, if there are multiple controlled equipment 3 on a floor, one receiver 4 is provided for each controlled equipment 3. In the example shown in FIG. 3, one dedicated receiver 4 is provided for each of the multiple lights. The receiver 4 is provided in a position close to the target controlled equipment 3. The receiver 4 is provided on the power line connected to the target controlled equipment 3, thereby establishing a physical one-to-one correspondence with the target controlled equipment 3. The receiver 4 and the controlled equipment 3 may be configured as a single device. For example, an LED light with a slave unit may be used. In this case, a single device includes a unit that functions as the receiver 4 and a unit that functions as the controlled equipment 3. The two are connected by a wiring W3 within the single device. The receiver 4 may be provided on the same power line as the target controlled equipment, in which case the wiring W3 is also configured as a power line. Alternatively, the receiver 4 may be connected to a power line separate from the target controlled equipment, in which case the wiring W3 is also configured as a signal line. Note that the receiver 4 and the controlled equipment 3 do not necessarily have to have a one-to-one relationship; for example, a configuration may be adopted in which multiple controlled equipment 3 receive control information from a single receiver 4.

[0027] The receiving unit 4 adjusts the output strength of the controlled equipment 3 based on the control information from the transmitting unit 6. For example, the receiving unit 4 can generate a command signal for lighting to adjust the illuminance of lighting. The receiving unit 4 can generate a command signal for air conditioning to adjust the output strength of air conditioning.

[0028] A detailed block configuration of the receiving unit 4 will be described with reference to FIG. 2(b). FIG. 2(b) is a block configuration diagram of the receiving unit. The receiving unit 4 includes a communication unit 14, a processing unit 16, and a memory unit 17. The communication unit 14 is a unit that communicates with the transmitting unit 6 and the controlled equipment 3. The communication unit 14 has a circuit that receives control information via a power line communication signal from the transmitting unit 6. The communication unit 14 also has a circuit that converts the power line communication signal from the transmitting unit 6 into a signal that can be processed by the controlled equipment 3. The processing unit 16 is a unit that controls the overall operation of the receiving unit 4. The processing unit 16 is configured with a microprocessor and its peripheral circuits, etc. The memory unit 17 is a unit that stores programs and information required for the operation of the receiving unit 4. The memory unit 17 may include a memory element similar to that exemplified for the memory unit 13. For example, the memory unit 17 stores an address indicating the location of the receiving unit 4 within the building BD1.

[0029] The transmitter 6 shown in FIG. 1 is a device that receives detection information from the detector 2 and transmits control information (control signal) to the receiver 4 based on the detection information. The transmitter 6 is a parent device for the detector 2 and the receiver 4. The transmitter 6 receives detection information in the form of a power line communication signal from the detector 2 via the power line W2. The transmitter 6 transmits a signal in narrowband power line communication. The transmitter 6 outputs control information in the form of a power line communication signal to the receiver 4 via the power line W4. The transmitter 6 calculates control information for each controlled facility 3 based on at least one of preset settings and the detection information detected by the detector 1.

[0030] The detailed block configuration of the transmitter 6 will be described with reference to FIG. 2(c). FIG. 2(c) is a block configuration diagram of the transmitter. The transmitter 6 includes a communication unit 21, a processing unit 22, and a storage unit 23. The communication unit 21 is a unit that communicates with the detector 2 and the receiver 4. The communication unit 21 has a circuit that performs power line communication with the detector 2 and the receiver 4. The communication unit 21 also has a circuit that performs remote communication with external communication devices using the cloud. That is, the communication unit 21 of the transmitter 6 includes a PLC communication unit that handles power line communication between the detector 2 and the receiver 4, and a wireless communication unit such as LTE that handles network communication with the cloud. The processing unit 22 is a unit that controls the overall operation of the transmitter 6. The processing unit 22 includes a microprocessor and its peripheral circuits. The processing unit 22 calculates control information for controlling the ON / OFF switching of each light and air conditioning unit, adjustment of output strength, etc.

[0031] The memory unit 23 is a unit that stores programs and information necessary for the operation of the transmitter 6. The memory unit 23 may include a memory element similar to that exemplified in the memory unit 13. For example, the memory unit 23 stores addresses indicating the positions of the transmitter 6, each detection slave unit 2, and each receiver unit 4 within the building BD1, in a state where the addresses are linked to one another.

[0032] Here, the transmitter 6 shown in FIG. 1 is installed in a power distribution facility 50 that serves as the base point of an electrical path to the multiple receivers 4 and the detector slave units 2 within the control range of the transmitter 6. The power distribution facility 50 distributes and supplies power to the multiple receivers 4 and the detector slave units 2 that exist within the control range of the transmitter 6. The power distribution facility 50 has a power supply unit 51 that supplies power to the multiple receivers 4 and the detector slave units 2. The power supply unit 51 of the power distribution facility 50 corresponds to the power supply unit that serves as the base point of an electrical path to the multiple receivers 4 and the detector slave units 2 within the control range of the transmitter 6. The transmitter 6 is provided for the power supply unit 51. The transmitter 6 is provided closer to the power supply unit 51 than the detector slave units 2 and the receivers 4. Such power distribution facility 50 is, for example, a distribution board provided for the building BD1. Furthermore, an example of such a power supply unit 51 is a main breaker of the distribution board. The origin of an electric circuit is the most upstream point in the flow of power in the wiring network of the power lines in which multiple receiving units 4 and detection slave units 2 exist within the control range. In other words, even if another distribution board exists in the middle of the wiring network, that distribution board does not qualify as the origin of the electric circuit.

[0033] The state in which the transmitter 6 is installed in the power distribution equipment 50 means that the transmitter 6 is incorporated into the wiring structure of the power line of the power distribution equipment 50. Furthermore, the state in which the transmitter 6 is provided in the power supply unit 51 means that the transmitter 6 is electrically connected to the power line drawn from the power supply unit 51. When the power distribution equipment 50 has a power line that is branched into multiple lines and drawn out from the housing, the transmitter 6 is connected to each power line in a manner that allows the power line communication signal to be superimposed on each branched power line. When such an electrical connection relationship is established, the location of the transmitter main body of the transmitter 6 is not particularly limited. Specifically, the transmitter main body of the transmitter 6 may be arranged inside the housing of the power distribution equipment 50 (for example, the housing of the distribution board 10 described below), and the transmitter 6 may be connected to the wiring structure inside the housing of the power distribution equipment 50. Alternatively, the transmitter body of transmitter 6 may be disposed outside the housing of power distribution equipment 50, and transmitter 6 may be connected to the wiring structure inside the housing of power distribution equipment 50. In this case, the transmitter body of transmitter 6 may be attached to the outside of a door or side surface of power distribution equipment 50, and wiring may be inserted through a hole formed in the housing and connected to the wiring structure inside the housing of power distribution equipment 50.

[0034] Next, an example of a power line communication system 100 will be described with reference to FIG. 3. FIG. 3 is a schematic configuration diagram showing an example of a power line communication system and a cubicle according to an embodiment. FIG. 3 shows an example in which the power line communication system 100 is adopted for an equipment system 101 in a building BD1 having multiple floors F1 to F3. Note that the detector 1 and the detection slave unit 2 are omitted from FIG. 3. The building BD1 to which the power line communication system 100 is applied is, for example, an apartment building, an office, a store, a factory, a hospital, or other facility. The power line communication system 100 includes a receiving unit 4 and a transmitting unit 6. The power line communication system 100 further includes a promoting unit 33. The power line communication system 100 further includes a power source 7, distribution boards 10A, 10B, and 10C, and a cubicle 20. The power source 7 is a source of high-voltage current, such as a power plant. The equipment system 101 shown in FIG. 3 includes the cubicle 20 outside the building BD1. The facility system 101 also includes distribution boards 10A, 10B, and 10C on the respective floors F1, F2, and F3.

[0035] Cubicle 20 is connected to a transmitter 6 that transmits narrowband power line communication signals and a receiver 4 that receives the signals via power line W7. Cubicle 20 is a facility that houses equipment that converts high voltage from a power plant into a voltage that can be used in the facility. Cubicle 20 is composed of a transformer 31 that converts voltage, multiple (three in this case) breakers 32 that cut off overcurrent, an acceleration unit 33 installed between transformer 31 and the multiple breakers 32, and other equipment. Transformer 31 is connected to power line W5, through which high-voltage current from power source 7 flows. Furthermore, within the housing of cubicle 20, transformer 31 is connected to one acceleration unit 33 and three breakers 32 via power lines W6. The three power lines W6 connected to the three breakers 32 are each drawn out of the housing of cubicle 20, extended into building BD1, and connected to distribution boards 10A, 10B, and 10C on each floor. The breaker 32 for the first floor is connected to the distribution board 10A on floor F1 via a power line W7. The breaker 32 for the second floor is connected to the distribution board 10B on floor F2 via a power line W7. The breaker 32 for the third floor is connected to the distribution board 10C on floor F3 via a power line W7. The transformer 31 is electrically connected to the transmitting unit 6 by the power line W6 and the power line W7 (an example of a first electric circuit).

[0036] Distribution boards 10A, 10B, and 10C are electrical equipment that distribute power transmitted via power line W7 to load circuits installed within the floor. Distribution boards 10A, 10B, and 10C have a wiring structure in which a collection of circuit breakers, earth leakage circuit breakers, and other devices are installed internally. Distribution board 10A on the first floor distributes power by branching it into multiple (here, two) power lines W8. Multiple receivers 4 and controlled equipment 3 (lighting in Figure 3) are connected to each power line W8. Note that some power lines W8 may be connected to load equipment that does not have a receiver 4. Floors F2 and F3 have a wiring structure for power lines W8, receivers 4, controlled equipment 3, and load equipment similar to that of floor F1.

[0037] In the example shown in FIG. 3 , the control range of the transmitter 6 is the receiver 4 installed on a predetermined floor (here, floor F1) of the building BD1. Here, the distribution board 10A on floor F1 of the building BD1 is the origin of the electrical circuit. That is, the distribution board 10A corresponds to the power distribution equipment 50 that is the origin of the electrical circuit, and the main breaker 52 installed on the distribution board 10A corresponds to the power supply unit 51 that is the origin of the electrical circuit. Therefore, the transmitter 6 is installed in the power supply unit 51 that is the origin of the electrical circuit. The transmitter 6 is installed, for example, downstream of the main breaker 52. Here, downstream refers to the side of the power line W8 that is connected to the controlled equipment 3 to which power is supplied, as viewed from the power line W5 that is close to the power source 7. As described above, the transmitter 6 is electrically connected to the transformer 31 of the cubicle 20 by the power line W6 and the power line W7 (an example of a first electrical circuit). The receiver 4 and the controlled equipment 3 are electrically connected to the transmitter 6 and a power line W8 (an example of a second electrical path).

[0038] Next, the internal configuration of the distribution board 10A will be described with reference to Fig. 4. As shown in Fig. 4, the distribution board 10A is provided with a main breaker 52, branch breakers 53A and 53B, and a transmitting unit 6. Fig. 4 shows a structure for controlling lighting as the controlled equipment 3, among the components of the distribution board 10A. The distribution boards 10B and 10C have the same configuration as the distribution board 10A.

[0039] The main breaker 52 is a breaker that supplies power to the branch breakers 53A and 53B. The main breaker 52 also monitors the current value and cuts off the power supply when the current value exceeds a predetermined value. The main breaker 52 is a single-phase three-wire breaker, with a power line W20A connected to the L1-phase terminal, a power line W20B connected to the L2-phase terminal, and a power line W20C connected to the N-phase terminal on the ground side. The branch breaker 53A is connected to the L1-phase power line W20A and the N-phase power line W20C. The branch breaker 53B is connected to the L2-phase power line W20B and the N-phase power line W20C. The branch breaker 53A supplies power to each receiving unit 4 and controlled equipment 3 connected to the power line W8A in the hierarchy F1 (see FIG. 3). The branch breaker 53B supplies power to each receiver 4 and controlled equipment 3 connected to the power line W8B in the story F1 (see FIG. 3). As a result, the main breaker 52 supplies power to the receiver 4 and controlled equipment 3 via the three power lines W20A, W20B, and W20C.

[0040] In contrast, transmitting unit 6 is provided in main breaker 52 by being connected to power lines W20B, W20C associated with the "L2 phase-N phase" combination (first combination) in main breaker 52. Specifically, transmitting unit main body 25 of transmitting unit 6 is connected to L2 phase power line W20B via electric wire W30, and to N phase power line W20C via electric wire W31. This allows the signal from transmitting unit 6 to pass through power lines W20B, W20C associated with the "L2 phase-N phase" combination.

[0041] Here, the configuration and function of the facilitating unit 33 provided in the cubicle 20 shown in FIG. 3 will be described. The facilitating unit 33 is, for example, a ferrite core or a filter. The facilitating unit 33 according to this embodiment has two ferrite cores. The facilitating unit 33 is provided directly below the transformer 31 on the power line W6. The facilitating unit 33 being provided directly below the transformer 31 means that the facilitating unit 33 is provided on the power line between the transformer 31 and the transmitting unit 6, and that there is no configuration that increases the impedance by more than a predetermined value in the power line connecting the transformer 31 and the facilitating unit 33. The predetermined value is, for example, 0.01 Ω. The predetermined value may be 0.01 Ω or more and 0.1 Ω or less. The predetermined value is not limited to the above-described impedance value. The facilitating unit 33 being provided directly below the transformer 31 may also mean, for example, that there is no electrically intervening configuration in the power line connecting the transformer 31 and the facilitating unit 33.

[0042] The accelerating unit 33 is provided outside the distribution boards 10A, 10B, and 10C, and is provided in an electric path (either the power line W6 or the power line W7) between the transformer 31 and the distribution boards 10A, 10B, and 10C. For example, the accelerating unit 33 is provided on the power line W6 between the transformer 31 and the breaker 32. Specifically, the accelerating unit 33 may be disposed inside the housing of the cubicle 20, and the accelerating unit 33 may be connected to the wiring structure (power line W6) inside the housing of the cubicle 20. Alternatively, the accelerating unit 33 may be disposed outside the housing of the cubicle 20, and the accelerating unit 33 may be connected to the wiring structure (power line W6) inside the housing of the cubicle 20. In this case, the facilitating unit 33 may be attached to the outside of the door surface or side surface of the cubicle 20, and wiring may be inserted through a hole formed in the housing of the cubicle 20 and connected to the wiring structure (power line W6) inside the housing of the cubicle 20. Furthermore, the facilitating unit 33 does not have to be attached to the outer surface of the housing of the cubicle 20, and may be connected to the wiring structure (power line W6) inside the housing of the cubicle 20.

[0043] FIG. 5 is a schematic diagram showing the configuration of a cubicle according to one embodiment. As shown in FIG. 5, the transformer 31 of the cubicle 20 is a single-phase three-wire type, with a power line W60A connected to the L1-phase terminal, a power line W60B connected to the L2-phase terminal, and a power line W60C connected to the N-phase terminal on the ground side. Each breaker 32 is connected to the L1-phase power line W60A and the N-phase power line W60C. Each breaker 32 is connected to the power lines W60A, W60B, and W60C. As a result, each breaker 32 supplies power to distribution boards 10A, 10B, and 10C via the three power lines W60A, W60B, and W60C.

[0044] The facilitating unit 33 is provided according to the power line (phase) to which the receiving unit 4, which is the target for facilitating the flow of a signal from the transmitting unit 6, is connected. For example, in a case where the purpose is to facilitate the flow of a signal from the transmitting unit 6 to the receiving unit 4 provided on each power line extending from the L2 phase and the N phase, the facilitating unit 33 is provided on the power lines W60B, W60C related to the "L2 phase-N phase" combination (fourth combination) in the transformer 31, and is provided immediately below the transformer 31. Note that in this case, the transmitting unit 6 is provided on, for example, each of the power lines W20B, W20C extending from the L2 phase and the N phase (see FIG. 4). One ferrite core of the facilitating unit 33 is provided along the extension direction of the L2 phase power line W60B. The other ferrite core of the facilitating unit 33 is provided along the extension direction of the N phase power line W60C. These ferrite cores are provided, for example, on the radially outer side of the power lines W60B, W60C so as to surround the periphery of each of the power lines W60B, W60C.

[0045] The facilitating unit 33 facilitates the flow of signals from the transmitting unit 6 to the receiving unit 4 (see FIG. 3). That is, the facilitating unit 33 facilitates the flow of signals to the opposite side (downstream side) of the transformer 31. The facilitating unit 33 suppresses not only high-frequency noise but also signals of communication frequencies from flowing toward the transformer 31 side (upstream side) among narrow-band signals.

[0046] To promote the above-described signal flow, the promoting unit 33 adjusts the impedances of the power lines W6 and W7 so that they are greater than the impedance of the power line W8. In this embodiment, the promoting unit 33 adjusts the impedance of the power line W6 between the transformer 31 and the promoting unit 33 so that it is greater than the impedance of the power line W8 between the transmitter 6 and the receiver 4. The difference between the impedance value of the power line W6 and the impedance value of the power line W8 may be, for example, 0.01 Ω, or may be 0.01 Ω or greater and 0.1 Ω or less. The difference in impedance value is not limited to the above-described value. This allows the impedance to be increased in a circuit including a power line connected to the promoting unit 33 by using at least one of the fourth, fifth, and sixth combinations of the power line W6. By making the impedance of the power line W6 greater than the impedance of the power line W8, it is possible to prevent a signal output from the transmitter 6 from flowing upstream of the transmitter 6. In other words, it is possible to promote a signal that was intended to flow upstream to flow downstream of the transmitter 6. The upstream side here refers to the power line W5 side closer to the power source 7 when viewed from the power line W8 connected to the controlled facility 3 to which power is supplied.

[0047] Next, the operation and effect of the power line communication system 100 according to this embodiment will be described.

[0048] In the power line communication system 100 according to this embodiment, the transformer 31 and the transmitter 6 are electrically connected, and the transmitter 6 and the receiver 4 are also electrically connected. The facilitating unit 33 is provided directly below the transformer 31, and thus can facilitate signal flow on the power line W8 from the transmitter 6 to the receiver 4 in the power line W6 (an example of a first electrical path) upstream of the transmitter 6. In conventional power line communication systems, signals do not flow sufficiently downstream (toward the receiver) from the transmitter, and some or all of the signals flow upstream (toward the power source). This can prevent the receiver from acquiring sufficient information, resulting in a loss of some or all of the information that should be acquired. In the power line communication system 100 according to this embodiment, signal flow can be facilitated between the transmitter and the receiver connected to the power line to which the facilitating unit 33 is connected directly below the transformer 31. This allows the receiver 4 to properly acquire signals from the transmitter 6. Therefore, this power line communication system 100 can ensure appropriate communication quality. Furthermore, since the promotion unit 33 is provided directly below the transformer 31, there is no need to provide a promotion unit outside each of the distribution boards 10A, 10B, and 10C, and the flow of signals can be promoted collectively in the power lines connected to the transformer 31.

[0049] In the power line communication system 100, the receiver 4 is electrically connected to the transmitter 6 via a power line W8 (an example of a second electrical path), and the promoter 33 adjusts the impedance of the power line W6 so that it is greater than the impedance of the power line W8. In this case, the adjustment by the promoter 33 makes the impedance of the power line W6 greater than the impedance of the power line W8, so that signals from the transmitter 6 are more likely to flow to the power line W8 than to the power line W6. In other words, it is possible to prevent signals from flowing from the transmitter 6 toward the upstream power lines W6 and W7. Therefore, the promoter 33 can promote the flow of signals from the transmitter 6 to the receiver 4, thereby ensuring appropriate communication quality.

[0050] The power line communication system 100 further includes distribution boards 10A, 10B, and 10C that accommodate a master breaker 52 installed on a power line W7 between the transformer 31 and the transmitter 6. The acceleration unit 33 is installed outside the distribution boards 10A, 10B, and 10C on the power line W6 or W7 between the transformer 31 and the distribution boards 10A, 10B, and 10C. In this case, the acceleration unit 33 is installed outside the distribution boards 10A, 10B, and 10C directly below the transformer 31. If acceleration units are installed in each of the distribution boards 10A, 10B, and 10C, it would be time-consuming to determine the impedance on the transformer side and then adjust the impedance in each distribution board accordingly. For example, while installing an acceleration unit within the distribution board can prevent signals from flowing outside the distribution board, installing an acceleration unit in each distribution board increases the labor required for installation and maintenance. Unlike broadband power line communication (power line communication using a frequency band between 2 MHz and 30 MHz), narrowband power line communication does not require adjustments to prevent signals from leaking from the transmitter outside the distribution board under Radio Law regulations. In other words, narrowband power line communication does not impose restrictions on the location of the accelerator. Therefore, in this power line communication system 100, there is no need to provide an accelerator in each of the distribution boards 10A, 10B, and 10C. By providing accelerator 33 directly below transformer 31, signal flow can be accelerated in a single system. When accelerator 33 is provided outside distribution boards 10A, 10B, and 10C as described above, it can be installed and adjusted in a single system once the impedance of power line W6 (or power line W7), which is part of the circuit upstream of accelerator 6, is determined. Furthermore, when the impedance of power line W6 is adjusted to be larger than the impedance of power line W8, the flow of signals downstream from the transmitter 6 can be promoted, and the flow of signals to the outside of the upstream of the distribution boards 10A, 10B, and 10C can be suppressed. Therefore, in this power line communication system 100, the facilitating unit 33 can be easily installed and maintained depending on the type, connection status, and number of equipment downstream of the transformer 31. This power line communication system 100 reduces the labor required to install and maintain a facilitating unit in each of the distribution boards 10A, 10B, and 10C, and can promote the flow of signals collectively to each of the distribution boards 10A, 10B, and 10C.

[0051] In the power line communication system 100, the frequency of the signal is equal to or greater than 10 kHz and equal to or less than 450 kHz.

[0052] In the power line communication system 100, the facilitating unit 33 is provided in at least one of the three-phase electric paths of the power line W6. In this embodiment, the facilitating unit 33 functions to facilitate signal flow in the receiving unit 4 and the transmitting unit 6 connected to at least the L2 phase and the N phase. The location of the facilitating unit 33 can be changed or expanded depending on the phase of the power line to which the receiving unit 4 and the transmitting unit 6 are connected. Therefore, the power line communication system 100 can minimize the number of facilitating units 33 installed, facilitating the installation and maintenance of the facilitating units 33. Furthermore, compared to when a ferrite core is provided for one phase, when a ferrite core is provided for two phases as in this embodiment, the power line communication system 100 can more strongly facilitate signal flow in the receiving unit 4 and the transmitting unit 6 connected to the two phases.

[0053] In the cubicle 20, the transformer 31 and the power line communication system 100 having the receiving unit 4 and the transmitting unit 6 are electrically connected by the power lines W6 and W7. The accelerating unit 33 is provided directly below the transformer 31, and therefore can accelerate the flow of signals from the transmitting unit 6 to the receiving unit 4 in the cubicle 20 upstream of the transmitting unit 6. This allows the receiving unit 4 to properly acquire the signal from the transmitting unit 6. Therefore, the cubicle 20 can ensure appropriate communication quality. Furthermore, it is not necessary to provide an accelerating unit in each of the distribution boards 10A, 10B, and 10C connected to the cubicle 20. The accelerating unit 33 provided in the cubicle 20 can collectively accelerate the flow of signals in the electrical circuit (power line W8) downstream of the cubicle 20.

[0054] The cubicle 20 is electrically connected to the transformer 31 by a power line W6 and has multiple breakers 32 provided between the transformer 31 and the transmitting unit 6, and the acceleration unit 33 is provided between the transformer 31 and the breakers 32. In this case, if the acceleration unit is installed and maintained downstream of each breaker, the labor required to install and maintain the acceleration unit increases or decreases depending on the number of breakers. On the other hand, in this embodiment, the acceleration unit 33 is installed between the transformer 31 and the multiple breakers 32, upstream before branching into the multiple breakers 32, so the labor required to install and maintain the acceleration unit 33 can be reduced compared to when it is installed downstream of each breaker.

[0055] The present invention is not limited to the above-described embodiments.

[0056] For example, the arrangement, positions and numbers of the controlled equipment 3, receiving unit 4, transmitting unit 6, facilitating unit 33 and load equipment on each floor shown in FIG. 3 are not particularly limited and may be changed as appropriate.

[0057] For example, the combination of power lines to which transmitting unit 6 is connected is not limited. Transmitting unit 6 may be provided in main breaker 52 by being connected to power lines W20A and W20C associated with the combination of "L1 phase-N phase" (second combination) in main breaker 52. This allows a signal from transmitting unit 6 to pass through power lines W20A and W20C associated with the combination of "L1 phase-N phase". Transmitting unit 6 may be provided in main breaker 52 by being connected to power lines W20A and W20B associated with the combination of "L1 phase-L2 phase" (third combination) in main breaker 52. This allows a signal from transmitting unit 6 to pass through power lines W20A and W20B associated with the combination of "L1 phase-L2 phase".

[0058] Furthermore, the number of transmitter bodies 25 of transmitter 6 is not limited. A plurality of transmitter bodies 25 may be provided in distribution board 10A and connected to the power lines associated with a plurality of combinations among the first, second, and third combinations described above. This allows signals output from transmitter 6 to be transmitted to receivers 4 connected to the respective power lines.

[0059] Furthermore, the combination of power lines to which the facilitating unit 33 is connected is not limited. For example, if the purpose is to promote the flow of signals from the transmitting unit 6 to the receiving units 4 provided on each power line extending from the L1 phase and the N phase, the facilitating unit 33 may be provided on the power lines W60A, W60C related to the "L1 phase-N phase" combination (fifth combination) in the transformer 31, and may be provided immediately below the transformer 31. In this case, the transmitting unit 6 is provided on each power line extending from the L1 phase and the N phase, for example. One ferrite core of the facilitating unit 33 is provided along the extension direction of the L1 phase power line W60A. The other ferrite core of the facilitating unit 33 is provided along the extension direction of the N phase power line W60C.

[0060] For example, when the purpose is to promote the flow of signals from the transmitter 6 to the receivers 4 provided on the power lines extending from the L1 and L2 phases, the promoter 33 may be provided on the power lines W60A, W60B associated with the "L1-L2 phase" combination (sixth combination) in the transformer 31, and may be provided directly below the transformer 31. In this case, the transmitter 6 is provided on each power line extending from the L1 and L2 phases, for example. One ferrite core of the promoter 33 is provided along the extension direction of the L1-phase power line W60A. The other ferrite core of the promoter 33 is provided along the extension direction of the L2-phase power line W60B.

[0061] The number of ferrite cores in the facilitating unit 33 is not limited. The number of ferrite cores in the facilitating unit 33 may be set according to the number of power lines extending from each phase of the transformer 31. For example, one ferrite core may be provided in the cubicle 20 for each of the three phases, L1, L2, and N (a total of three ferrite cores). This makes it possible to accommodate the fourth, fifth, and sixth combinations described above. That is, the facilitating unit 33 may include a ferrite core provided along the extension direction of the L1-phase power line W60A, a ferrite core provided along the extension direction of the L2-phase power line W60B, and a ferrite core provided along the extension direction of the N-phase power line W60C. In this case, the signal flow can be collectively promoted for the receiving unit 4 and the transmitting unit 6 connected to any of the L1, L2, and N phases.

[0062] For example, one ferrite core may be provided in the cubicle 20 for three phases, namely, the L1 phase, the L2 phase, and the N phase. In this case, the ferrite core of the facilitating unit 33 is provided for one power line (first phase) of two power lines (two phases) connected to the receiving unit 4 for which the signal flow from the transmitting unit 6 is to be promoted. This form is applied, for example, when the phases to which the receiving unit 4 and the transmitting unit 6 are connected have already been determined. In this case, the facilitating unit 33 can be provided more easily than when ferrite cores are provided for multiple phases, and the signal flow can be promoted more easily.

[0063] FIG. 6 is a schematic diagram showing the configuration of a cubicle according to a modified example. As shown in FIG. 6, a terminal block 34 may be provided in the cubicle 20. The L1-phase power line W60A of the transformer 31 is connected to terminal 35A of the terminal block 34, the L2-phase power line W60B is connected to terminal 35B of the terminal block 34, and the grounded N-phase power line W60C is connected to terminal 35C of the terminal block 34. The breakers 32 for each of the floors F1, F2, and F3 are connected to the L1-phase terminal 35A, the L2-phase terminal 35B, and the N-phase terminal 35C, respectively. As a result, the transformer 31 supplies power to the controlled equipment 3 and the receiver 4 on each of the floors F1, F2, and F3 via the three power lines W60A, W60B, and W60C. The connections of the promoter 33A to each of the power lines W60A, W60B, and W60C are the same as those shown in FIG. 5. The facilitating unit 33A is provided, for example, between the transformer 31 and the terminal block 34. In this case, the number of power lines on which the facilitating unit 33A can be installed can be reduced compared to when the facilitating unit is provided downstream of the terminal block or downstream of multiple breakers, thereby reducing the number of installation and maintenance steps. Note that the facilitating unit 33A may also be provided, for example, between the terminal block 34 and multiple breakers 32. In this case, the number of power lines on which the facilitating unit 33A can be installed can be reduced compared to when the facilitating unit is provided downstream of multiple breakers, thereby reducing the number of installation and maintenance steps.

[0064] The transmitting unit 6 may be provided in the cubicle 20. In this case, the facilitating unit 33 is provided between the transformer 31 and the transmitting unit 6.

[0065] FIG. 7 is a schematic diagram illustrating a power line communication system according to a modified example. As shown in FIG. 7, the power line communication system 100A does not necessarily have a cubicle. The power line communication system 100A includes a transmitter 6A electrically connected to a voltage-changing transformer 31A via power lines W6 and W7 and configured to transmit a signal for narrowband power line communication; a receiver 4A electrically connected to the transmitter 6A via power line W8 and configured to receive the signal; and a promoter 33A provided directly below the transformer 31A on the power line W6 and configured to promote signal flow from the transmitter 6A to the receiver 4A. The receiver 4A is a slave unit provided for the controlled equipment 3A (lighting in FIG. 7). The transformer 31A is electrically connected to a power source 7 via a power line W5. The transmitter 6A is provided in a distribution board 10D electrically connected to the transformer 31A. The promoter 33A is provided between the transformer 31A and the distribution board 10D. That is, the accelerating unit 33A is provided immediately below the transformer 31A and upstream of the distribution board 10D. In this modification, devices and configurations with the same names as those in the above-described embodiment, but with different reference numerals, exert the same functions and effects.

[0066] The building BD2 to which the power line communication system 100A shown in FIG. 7 is applied may be, for example, a facility such as a detached house. When the building BD2 in which the receiving unit 4 and the transmitting unit 6 are provided is a detached house or the like, the transformer 31A is not provided in a cubicle, for example. The transformer 31A is provided, for example, on a utility pole outside the building BD2. The transformer 31A is electrically connected to a distribution board 10D in the building BD1 via a power line W7. The power line communication system 100A having such a configuration can also achieve the same functions and effects as the power line communication system 100. [Example]

[0067] The signal strength of the receiving section due to the provision of the boosting section directly below the transformer was detected, and the function and effect of the boosting section were verified.

[0068] [Comparative Example 1] FIG. 8(a) is a circuit diagram of a power line communication system according to a comparative example before a transformer and a promotion unit are installed. As shown in FIG. 8(a), a power line communication system 100P according to comparative example 1 includes a controlled facility 3P, a receiving unit 4P, and a transmitting unit 6P. The controlled facility 3P, the receiving unit 4P, and the transmitting unit 6P are electrically connected in parallel. Each component is operated by a power source (not shown). The transmitting unit 6P continuously outputs a power line communication signal (PLC signal) of 100 kHz or more and 400 kHz or less to the controlled facility 3P and the receiving unit 4P. The controlled facility 3P is an example of a load. The receiving unit 4P is, for example, a spectrum analyzer. The receiving unit 4P has a resistance value of 50 Ω and is connected to the end of the circuit. The receiving unit 4P detects the signal from the transmitting unit 6P.

[0069] 8(b) is a graph of experimental results showing the signal spectrum of the receiving unit before the transformer and the acceleration unit were installed. As shown in FIG. 8(b), the receiving unit 4P detected a signal of approximately -20 dBm in the frequency range of 100 kHz to 400 kHz. It was also shown that the receiving unit 4P detected signals with approximately constant intensity in the frequency range of 100 kHz to 400 kHz, which is the frequency band of the signal output from the transmitting unit 6P. Furthermore, in other frequency bands not output from the transmitting unit 6P, such as 50 kHz to less than 100 kHz and more than 400 kHz to 1000 kHz, signals of approximately -70 dBm were detected.

[0070] Comparative Example 2 9A is a circuit diagram of a power line communication system according to a comparative example after a transformer is installed but before a promoter is installed. As shown in FIG. 9A, a power line communication system 100Q according to a second comparative example includes a controlled facility 3Q, a receiving unit 4Q, and a transmitting unit 6Q. The power line communication system 100Q further includes a transformer 31Q. The controlled facility 3Q, the receiving unit 4Q, the transmitting unit 6Q, and the transformer 31Q are electrically connected in parallel. The transmitting unit 6Q is provided between the transformer 31Q and the controlled facility 3Q and the receiving unit 4Q. The controlled facility 3Q, the receiving unit 4Q, and the transmitting unit 6Q are operated by power supplied via the transformer 31Q. The transformer 31Q receives power from a power source (not shown). The transmitting unit 6Q continuously outputs a power line communication signal of 100 kHz or more and 400 kHz or less to the controlled facility 3Q and the receiving unit 4Q. The controlled facility 3Q is an example of a load. The receiver 4Q is, for example, a spectrum analyzer. The receiver 4Q has a resistance value of 50 Ω and is connected to the end of the circuit. The receiver 4Q detects a signal from the transmitter 6Q. The transformer 31Q has the same function as the transformer 31 in the above embodiment.

[0071] Figure 9(b) is a graph of experimental results showing the signal spectrum at the receiving unit after the transformer was installed but before the acceleration unit was installed. As shown in Figure 9(b), receiving unit 4Q detected signals in the range of -80 dBm to -55 dBm in the frequency range of 100 kHz to 400 kHz. It was also confirmed that the higher the frequency in the frequency range of 100 kHz to 400 kHz, the higher the detected strength. Furthermore, in other frequency bands not output from transmitting unit 6Q, such as 50 kHz to less than 100 kHz and 400 kHz to 1000 kHz, signals of approximately -90 dBm were detected.

[0072] [Example] FIG. 10(a) is a circuit diagram of the power line communication system according to the embodiment after the transformer and the facilitating unit are installed. As shown in FIG. 10(a), the power line communication system 100R according to the embodiment includes a controlled facility 3R, a receiving unit 4R, a transmitting unit 6R, and a facilitating unit 33R. The power line communication system 100R further includes a transformer 31R. The controlled facility 3R, the receiving unit 4R, the transmitting unit 6R, and the transformer 31R are electrically connected in parallel. The transmitting unit 6R is provided between the transformer 31R and the controlled facility 3R and the receiving unit 4R. The controlled facility 3R, the receiving unit 4R, and the transmitting unit 6R are operated by power supplied via the transformer 31R. The transformer 31R receives power from a power source (not shown). The transmitting unit 6R continuously outputs a power line communication signal of 100 kHz or more and 400 kHz or less to the controlled facility 3R and the receiving unit 4R. The controlled facility 3R is an example of a load. The receiving unit 4R is, for example, a spectrum analyzer. The receiving unit 4R has a resistance value of 50 Ω and is connected to the end of the circuit. The receiving unit 4R detects a signal from the transmitting unit 6R. The transformer 31R has the same function as the transformer 31 in the above embodiment. The facilitating unit 33R is provided on each of the two power lines connected to the transmitting unit 6R. The facilitating unit 33R is, for example, a ferrite core.

[0073] Figure 10(b) is a graph of experimental results showing the signal spectrum at the receiving unit after the transformer and the acceleration unit were installed. As shown in Figure 10(b), the receiving unit 4R detected signals in the range of approximately -20 dBm in the frequency range of 100 kHz to 400 kHz. It was also shown that the receiving unit 4P detected signals with approximately constant intensity in the frequency range of 100 kHz to 400 kHz, which is the frequency band of the signal output from the transmitting unit 6P. Furthermore, in other frequency bands not output from the transmitting unit 6R, such as 50 kHz to less than 100 kHz and more than 400 kHz to 1000 kHz, signals of approximately -70 dBm were detected.

[0074] Comparing the results of Comparative Example 1 with those of the Example revealed that even when the transformer 31R is connected to the power line communication system 100P, the signal strength detected by the receivers 4P and 4R is substantially the same regardless of the frequency band. Comparing the results of Comparative Example 1 and Comparative Example 2, on the other hand, revealed that when the transformer 31Q is connected to the power line communication system 100P, the signal strength detected by the receivers 4P and 4Q is reduced in each frequency band. Furthermore, in Comparative Example 1 and the Example, within the frequency range of 100 kHz to 400 kHz, which is the frequency band of the signals output from the transmitters 6P, 6Q, and 6R, the signal strength detected by the receivers 4P and 4R is constant regardless of frequency. However, within this frequency range, in Comparative Example 2, the signal strength detected by the receiver 4Q varies depending on the frequency. These results revealed that even when a transformer is connected to the circuits of the controlled equipment, the receiver, and the transmitter, providing a promotion unit allows the receiver to properly detect the signal from the transmitter.

[0075] When the transformer 31Q is directly connected to the transmitter 6Q as shown in (a) of Fig. 9, the signal output from the transmitter 6Q flows not only to the receiver 4Q (downstream) but also to the transformer 31Q (upstream), which is presumably why the signal strength detected by the receiver 4Q of Comparative Example 2 is low. On the other hand, when the transformer 31R is connected to the transmitter 6R via the facilitating unit 33R as shown in (a) of Fig. 10, the signal output from the transmitter 6R is prevented from flowing to the transformer 31R (upstream) and is promoted to flow to the receiver 4Q (downstream). This is presumably why the signal strength detected by the receiver 4R is similar to the signal strength detected by the receiver 4P of the embodiment. Therefore, by providing a facilitating unit between the transformer and the transmitter, the power line communication system can ensure appropriate communication quality between the transmitter and receiver. [Explanation of symbols]

[0076] 3, 3P, 3Q, 3R...controlled equipment, 4, 4A, 4P, 4Q, 4R...receiving unit, 6, 6A, 6P, 6Q, 6R...transmitting unit, 7...power supply, 10A, 10B, 10C, 10D...distribution board (power distribution equipment), 20...cubicle (power distribution equipment), 31, 31A, 31Q, 31R...transformer (power supply unit), 32...breaker, 33...promotion unit, 50...power distribution equipment, 51...power supply unit, 52...main breaker, 100...power line communication system.

Claims

1. a transmitter electrically connected to the transformer that converts a voltage from high to low by a first electric path, the transmitter transmitting a signal in a frequency band of 10 kHz to 450 kHz in power line communication; a receiving unit electrically connected to the transmitting unit and receiving the signal; a distribution board accommodating a main breaker provided on the first electric circuit between the transformer and the transmitting unit; a promotion unit that is provided directly below the transformer on the first electric path, outside the distribution board, on the first electric path between the transformer and the distribution board, and that promotes the flow of the signal from the transmitting unit to the receiving unit and suppresses the flow of the signal from the transmitting unit to the transformer side; A power line communication system comprising:

2. the receiving unit is electrically connected to the transmitting unit by a second electrical path, The power line communication system according to claim 1 , wherein the promoting unit adjusts the impedance of the first electrical path so that it is greater than the impedance of the second electrical path.

3. A power line communication system as described in claim 1 or 2, wherein the power line communication is performed using the DCSK method.

4. The power line communication system according to any one of claims 1 to 3, wherein the promotion unit is provided in at least one of the first electric circuits, which are divided into three phases.

5. A cubicle connected to a power line communication system, comprising a distribution board accommodating a main breaker, and a transmitter for transmitting a signal in a frequency band of 10 kHz to 450 kHz in power line communication and a receiver for receiving said signal, a transformer electrically connected to the power line communication system by a first electric path, the transformer changing a voltage from a high voltage to a low voltage; a promotion unit provided in the first electric path between the distribution board and the transformer immediately below the transformer, the promotion unit promoting the flow of the signal toward the downstream side, which is the direction in which power is supplied, and suppressing the flow of the signal toward the upstream side opposite to the downstream side; Equipped with a cubicle.

6. the cubicle has a plurality of breakers electrically connected to the transformer by the first electric path and provided between the transformer and the transmitting unit, The cubicle according to claim 5 , wherein the facilitating section is provided between the transformer and the breaker.

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