WO2013136662A1

WO2013136662A1 - Power meter

Info

Publication number: WO2013136662A1
Application number: PCT/JP2013/000790
Authority: WO
Inventors: 省互一村; 明実塩川; 雄介宮村; 高士渡邊
Original assignee: パナソニック株式会社
Priority date: 2012-03-12
Filing date: 2013-02-14
Publication date: 2013-09-19
Also published as: TWI493197B; CN104160282B; JP2013190208A; CN104160282A; TW201341809A

Abstract

　This power meter is equipped with: a power measurement unit that measures power; a communication terminal that is used for a connection with a communication line; a communication unit that outputs the power value measured by the power measurement unit to the communication line connected to the communication terminal; a first ground terminal that is used for a connection with a grounding line for grounding the power meter; a second ground terminal that is used for a connection with a shield line that electromagnetically shields the communication line; and a surge protection means that is connected between the first ground terminal and the second ground terminal.

Description

Power meter

The present invention relates to a power meter.

In office buildings, retail stores, universities, etc., electricity received from the distribution system of the power company is split into multiple branch circuits using the switchboard and distribution board, and power is supplied to the loads connected to each branch circuit. is doing.

Previously, the main current was measured at the point of power distribution, and the total power consumption was measured based on this main current. However, in recent years, awareness of power saving and power saving has increased, and individual branch circuits have There is a demand to measure power consumption and to consider measures for power saving and power saving. For example, the multi-circuit wattmeter disclosed in Document 1 (Japanese Published Patent Publication No. 2005-55404) can measure power consumption at a plurality of points, and increase the number of measurement points by adding an extension unit. be able to.

Since the multicircuit wattmeter disclosed in the above-mentioned document 1 is installed on the switchboard or distribution board, in order to confirm the measurement result of the power consumption, it is necessary to go to the installation place of the distribution board or distribution board. , It took time and effort.

Therefore, the power consumption measurement results are periodically transmitted from the multi-circuit power meter to an external device (for example, a management server) installed in a place where it can be easily seen by power consumers and facility managers. It can be displayed on the device.

In this case, the connection terminal for connecting the communication line connecting the communication unit provided in the multi-circuit power meter and the external device is provided in a state where it is exposed on the surface of the multi-circuit power meter.

Therefore, when some work is performed in the panel (for example, work for connecting a communication line to the connection terminal), the operator's body may touch the connection terminal. If static electricity charged on the operator's body is discharged to the connection terminal when the communication unit is not grounded, surge voltage or surge current due to static electricity may be applied to the circuit components that make up the communication unit. was there.

Therefore, it is necessary to use high voltage components for the circuit components constituting the communication unit, resulting in an increase in cost.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a power measuring instrument in which a surge voltage and a surge current applied to circuit components constituting a communication unit are reduced.

A power measuring instrument according to a first aspect of the present invention includes a power measuring unit that measures power, a communication terminal used for connection with a communication line, and the power measurement on the communication line connected to the communication terminal. A communication unit that outputs a value of power measured by the unit, a first ground terminal used for connection to a ground line for grounding the power measuring instrument, and a shield wire that electromagnetically shields the communication line A second grounding terminal used for connection; and surge protection means connected between the first grounding terminal and the second grounding terminal.

In the power meter of the second form according to the present invention, in the first form, the surge protection means is configured to conduct between the first ground terminal and the second ground terminal when a surge occurs. The

In the power meter of the third form according to the present invention, in the first or second form, the surge protection means is a surge protection device.

In the power meter of the fourth form according to the present invention, in the third form, the surge protection device is a gap arrester.

A power meter according to a fifth aspect of the present invention includes a circuit board on which the first ground terminal and the second ground terminal are mounted in the first or second form. The surge protection means includes a first conductive layer connected to the first ground terminal and a second conductive layer connected to the second ground terminal. The first conductive layer and the second conductive layer are formed on the circuit board so as to face each other with a predetermined interval. The predetermined interval is set such that conduction between the first conductive layer and the second conductive layer occurs when a surge occurs.

In a sixth aspect of the power measuring instrument according to the present invention, in the fifth aspect, the circuit board includes a first circuit board and a second circuit board. The first ground terminal is mounted on the first circuit board. The second ground terminal is mounted on the second circuit board. The first conductive layer and the second conductive layer are formed on one of the first circuit board and the second circuit board.

According to a seventh aspect of the present invention, there is provided a power measuring instrument according to the first or second aspect, wherein the first circuit board having a first surface and the second circuit board having a second surface facing the first surface. And comprising. The first ground terminal is mounted on the first circuit board. The second ground terminal is mounted on the second circuit board. The surge protection means has a first protrusion and a second protrusion. The first protrusion is disposed on the first surface of the first circuit board and is electrically connected to the first ground terminal. The second protrusion is disposed on the second surface of the second circuit board so as to face the first protrusion with a predetermined gap, and is electrically connected to the second ground terminal. The The predetermined interval is set so that the first protrusion and the second protrusion are electrically connected when a surge occurs.

An eighth aspect of the power measuring instrument according to the present invention includes, in the seventh aspect, a first case that houses the first circuit board and a second case that houses the second circuit board. The first case has a first opening that exposes the first surface of the first circuit board. The second case has a second opening that exposes the second surface of the second circuit board. The second case is attached to the first case so that the second opening faces the first opening.

According to a ninth aspect of the present invention, there is provided a power measuring instrument according to any one of the first to eighth aspects, wherein the power terminal is used for connection to a power line from an external power source, and is connected to the power terminal. A power supply circuit unit that feeds power to the power measurement unit and the communication unit based on power received from the external power supply through the power line. The first connection terminal is connected to the power supply circuit unit.

In the power meter of the tenth aspect according to the present invention, in any one of the first to ninth aspects, the first connection terminal is connected to the power measurement unit.

It is a block diagram which shows the state in which the communication line is not connected in the main body unit of the electric power measuring device of one Embodiment of this invention. It is a block diagram which shows the state in which the communication line is connected in the main body unit of the said electric power measuring device. It is a schematic sectional view of the main unit of the power meter. (A) is a front view of the power meter, (b) is a top view of the power meter, and (c) is a bottom view of the power meter. It is a left view of the said electric power measuring device. It is a right view of the said electric power measuring device. It is an external appearance perspective view of the power meter. It is an external appearance perspective view of the state which isolate | separated the main body unit and extension unit of the said electric power measuring device. It is a schematic sectional drawing which shows the 1st modification of the said electric power measuring device. It is a schematic sectional drawing which shows the 2nd modification of the said electric power measuring device.

1. Configuration of power measuring instrument A power measuring instrument according to an embodiment of the present invention is installed together with a main switch and a branch switch in a panel such as a switchboard or a distribution board, for example. Used to measure the amount of power.

As shown in FIGS. 4 to 8, the power measuring instrument of the present embodiment includes a main unit 1A and one or more extension units 1B connected to the main unit 1A as necessary.

1 and 2 are block diagrams of the main unit 1A.

The power meter displays the power consumption measurement result on the display unit or stores it in a memory card, and uses it to send the measurement result to an external device connected via a communication line. There is a method.

FIG. 1 shows a wiring configuration when the power meter is used alone, and FIG. 2 shows a wiring configuration when the power meter is connected to the management apparatus 100 which is an external device.

Generally, it is considered that the power meter is often used alone at the initial stage of introduction of the power meter into the power distribution system. When the power meter is used alone, the user needs to regularly go to the place where the power meter is installed and collect the memory card in order to collect the measurement data stored in the memory card. . During the subsequent operation, the user is expected to increase the number of measurement objects. When the measurement object exceeds a certain scale, a communication line is used between the power meter and the management apparatus 100 to facilitate collection of measurement data. It is thought that measurement data will be transmitted by communication after connection.

The main unit 1A constituting the power measuring instrument of the present embodiment includes a power measuring unit 10 (current measuring unit 11, voltage measuring unit 12, and power calculating unit 13), a memory card interface unit 14, and a communication unit 15. A display unit 16, a power supply circuit unit 17, and a gap arrester 18. The main unit 1A only needs to include at least the power measuring unit 10, the communication unit 15, and the gap arrester 18.

The output line CB4 of the current transformer 11a is connected to the current measuring unit 11. An electric wire through which a current to be measured flows is inserted into the core hole of the current transformer 11a. The current measuring unit 11 measures the current value to be measured based on the output signal of the current transformer 11a.

In the three-phase four-wire distribution method, current is measured in each of the R phase, S phase, and T phase, so that three current transformers 11a are required, and the connection portions to which the current transformers 11a are connected respectively. Three (not shown) are required for each circuit.

Further, in the present embodiment, three connection portions are set as one set so that the current for three circuits can be measured by one main unit 1A, and three sets (that is, nine) of connection portions are the main unit 1A. Is provided.

The voltage measuring unit 12 detects the voltage applied to the circuit to be measured, that is, the power supply voltage of the commercial AC power supply AC that is an external power supply. In the three-phase four-wire distribution method, the voltage of each phase is measured by the voltage measuring unit 12. Note that the voltage applied to the circuit to be measured is not limited to the voltage of the external power supply.

The power calculation unit 13 periodically fetches the measurement results from the current measurement unit 11 and the voltage measurement unit 12, and uses the measured values of the current and voltage and the phase difference between the current and voltage, Data such as power consumption is calculated. The power calculation unit 13 outputs measurement results such as power consumption and power consumption to the memory card I / F unit 14, the communication unit 15, and the display unit 16. The current measuring unit 11, the voltage measuring unit 12, and the power calculating unit 13 constitute a power measuring unit 10.

That is, the power measuring instrument of this embodiment includes a power measuring unit 10 that measures power. In the present embodiment, the power measuring unit 10 is configured to measure the power consumption of the load. The power measured by the power measuring unit 10 includes power supplied from a power source (supplied power), power generated by a power generation device (such as a solar cell) (power generation power), and power stored in a power storage device (power storage power). )

The memory card interface unit (hereinafter referred to as a memory card I / F unit) 14 includes a card slot to which a memory card MC1 such as an SD card is detachably connected. When the measurement result is input from the power calculation unit 13, the memory card I / F unit 14 writes data to the memory card MC1, and the measurement data such as power consumption and power consumption for each circuit is sometimes stored. Records in series on the memory card MC1. The power calculation unit 13 may store measurement data such as power consumption and power consumption measured for each circuit in a main body memory (not shown).

The communication unit 15 conforms to the RS485 standard, which is a communication standard for serial communication. As shown in FIG. 2, the communication unit 15 is connected to an external device (transmission side and reception side communication line CB5 (Tx line, Rx line) each composed of a twisted pair line. In this embodiment, it is connected to the management apparatus 100) and performs serial communication with the management apparatus 100.

When the management device 100 is connected to the main unit 1 A, when the measurement result is input from the power calculation unit 13, the communication unit 15 transmits the measurement result to the management device 100. As will be described later, the management apparatus 100 is connected to the power meter using the communication line CB5. The power meter has a communication terminal (connection terminal) T15 used for connection with the communication line CB5. The communication unit 15 outputs the power value measured by the power measurement unit 10 to the communication line CB5 connected to the communication terminal 15. In this way, the communication unit 15 transmits the measurement result (the power value measured by the power measurement unit 10) to the management apparatus 100.

In addition, the main unit 1A transmits the past measurement result stored in the memory card MC1 from the communication unit 15 to the management apparatus 100 in response to a transmission request from the management apparatus 100. The main unit 1 A may cause the past measurement results stored in the main body memory to be transmitted from the communication unit 15 to the management apparatus 100 in response to a transmission request from the management apparatus 100.

The display unit 16 is configured by a liquid crystal display, for example, and displays the measurement result when the measurement result is input from the power calculation unit 13. The display unit 16 displays various setting contents and operation states in addition to the measurement results. The display unit 16 may be integrated with the main unit 1A, may be a separate unit, or may be a display lamp such as a light emitting diode.

The power supply circuit unit 17 is supplied with power from the commercial AC power supply AC, which is an external power supply, via the power cable CB1, and receives a current measurement unit 11, a voltage measurement unit 12, a power calculation unit 13, and a memory card I / F unit 14. Then, operation power for the communication unit 15 and the display unit 16 is generated and supplied to each unit. The power supply circuit unit 17 supplies operating power to the extension unit 1B connected to the main unit 1A.

Here, among the circuits shown in FIGS. 1 and 2, the high-power circuit including the power measurement unit 10 (comprising the current measurement unit 11, the voltage measurement unit 12, and the power calculation unit 13) and the power supply circuit unit 17 is the first. The low-power circuit including the communication unit 15 mounted on the circuit board B1 is mounted on the second circuit board B2.

A strong electric circuit is, for example, a circuit for supplying power as power (a circuit that uses electricity as energy). The weak electric system circuit is, for example, a circuit for transmitting an electric signal (a circuit using electricity as a signal). In general, the voltage of a strong electric circuit is higher than the voltage of a weak electric circuit. If the voltage applied to the circuit is greater than or equal to a predetermined value (48V or 60V), the circuit may be a high-power circuit, and if the voltage applied to the circuit is less than a predetermined value, the circuit may be a weak-electric circuit.

1 and 2, the current measurement unit 11, the voltage measurement unit 12, and the power calculation unit 13 are illustrated as being mounted on the first circuit board B 1, but the current measurement unit 11 and the power calculation unit 13 are illustrated. Since a strong current does not flow through the capacitor, it may be mounted on the second circuit board B2.

Further, each of the first circuit board B1 and the second circuit board B2 may be composed of one circuit board, or may be composed of a plurality of circuit boards. In this way, the strong electric circuit and the weak electric circuit are mounted on separate circuit boards, and the strong electric first circuit board B1 and the weak electric second circuit board B2 are arranged apart from each other. The noise applied to the weak electric circuit is reduced by the influence of the current and voltage flowing through the circuit.

Further, as shown in FIGS. 1 to 4, the main unit 1A includes connection terminals T11 to T13 and T15 to T17 each formed of a screw terminal device and a receptacle-type connector for electrical connection with an external circuit. Connector CN11. In the block diagrams of FIGS. 1 and 2, the connection terminal T17 and the connector CN11 are not shown. The connection terminals T11 to T13 and T15 to T17 are not limited to screw terminal devices.

The two-core power cable CB1 from the commercial AC power supply AC is connected to the connection terminal T11. A commercial AC power supply AC is supplied to the power supply circuit unit 17 via a connection terminal T11. That is, the connection terminal T11 is a power supply terminal used for connection with a power supply line (power supply cable CB1) from an external power supply (commercial AC power supply AC in this embodiment).

The connection terminal T12 is connected to a cable for inputting the voltage at the measurement point to the voltage measuring unit 12. In the case of three-phase four-wire distribution, the voltages of the R phase, S phase, and T phase are set. Are input through the cable CB2. That is, the connection terminal T12 is a voltage measurement terminal used for connection with a voltage measurement connection line.

The ground line CB3 for connecting the power supply circuit unit 17 to the ground (ground) is connected to the connection terminal T13 which is the first ground terminal. That is, the first ground terminal T13 is used for connection with the ground line CB3 for grounding the power meter. In this embodiment. The first ground terminal T13 is used for connection to the ground line CB3 for grounding the power supply circuit unit 17 of the power meter.

The communication line CB5 that connects between the communication unit of the management apparatus 100 and the communication unit 15 is connected to the connection terminal T15. The communication line CB5 is composed of one pair or two pairs of twisted pair lines (Tx line, Rx line), and the connection terminal T15 is composed of two or four screw terminal devices. That is, the connection terminal T15 is a communication terminal used for connection with the communication line CB5.

The connection terminal T16, which is the second ground terminal, is composed of two screw terminal devices, and each screw terminal device is connected to a shield wire CB6 that electromagnetically shields one or two pairs of twisted pair wires constituting the communication line CB5. Is done. That is, the second ground terminal T16 is used for connection with the shield line CB6 that electromagnetically shields the communication line CB5.

The connection terminal T17 and the connector CN11 are provided for connecting the output line CB4 of the current transformer 11a, and the output signal of the current transformer 11a is input to the current measuring unit 11 via the connection terminal T17 or the connector CN11. That is, the connection terminal T17 and the connector CN11 are current measurement terminals used for connection with a current measurement connection line. Note that the power meter only needs to include at least one of the connection terminal T17 and the connector CN11.

In the present embodiment, the current measurement unit 11 can be connected to any of two types (for example, 400A and 5A) of current transformers 11a having different measurement ranges. The circuit on the input side differs depending on the type of the current transformer 11a, and the output line CB4 is connected to the connection terminal T17 made of a screw terminal device in the current transformer 11a having a measurement range of 400A. In the current transformer 11a having a measurement range of 5A, the plug-type connector connected to the terminal of the output line CB4 is connected to the connector CN11 formed of a receptacle-type connector.

The gap arrester 18 is composed of, for example, a gas-filled discharge tube, and is mounted on the first circuit board B1 together with a high-voltage circuit as shown in FIG.

One terminal 181 of the gap arrester 18 is electrically connected to the connection terminal T13 (first ground terminal) via the wiring pattern 20 of the first circuit board B1. The other terminal 182 of the gap arrester 18 is electrically connected to a plated through hole (not shown) provided in the first circuit board B1 via the wiring pattern 21 of the first circuit board B1.

The second circuit board B2 is provided with a plated through hole (not shown) electrically connected to the connection terminal T16 (second ground terminal) via the wiring pattern 22 of the second circuit board B2. .

Both ends of the cable CB7 are soldered to the plated through holes of the first circuit board B1 and the second circuit board B2, respectively, and the gap between the first ground terminal T13 and the second ground terminal T16 via the gap arrester 18. A gap will be joined.

The gap arrester 18 is a surge protection means connected between the first ground terminal T13 and the second ground terminal T16. The surge protection means is configured to conduct between the first ground terminal T13 and the second ground terminal T16 when a surge occurs. For example, when a surge occurs, the potential difference between the first ground terminal T13 and the second ground terminal T16 exceeds a predetermined threshold. That is, the surge protection means electrically connects the first ground terminal T13 and the second ground terminal T16 if the potential difference between the first ground terminal T13 and the second ground terminal T16 is less than a predetermined threshold. Insulate. The surge protection means conducts between the first ground terminal T13 and the second ground terminal T16 if the potential difference between the first ground terminal T13 and the second ground terminal T16 is equal to or greater than a predetermined threshold. The predetermined threshold is a value (determination value) for determining whether or not a surge has occurred. For example, the predetermined threshold is larger than the voltage of the high voltage circuit and smaller than the surge voltage.

When this power measuring unit is used alone, the communication line CB5 is not connected to the connection terminal T15, and the shield line CB6 for electromagnetically shielding the communication line CB5 is also not connected to the second ground terminal T16. The communication unit 15 is not grounded.

The connection terminal T15 and the second ground terminal T16 are provided in a state of being exposed on the surface of the main unit 1A so that the communication line CB5 and the shield line CB6 can be connected.

Therefore, there is a possibility that the operator's body may come into contact with the connection terminal T15 or the second grounding terminal T16 when any work is performed in the panel on which the main unit 1A is installed. There is a possibility of flowing into the communication unit 15 from the connection terminal T15 or T16.

Even in such a case, in the present embodiment, since the first ground terminal T13 and the second ground terminal T16 are gap-coupled via the gap arrester 18, the static electricity is generated by the gap arrester 18 being conducted. One ground terminal T13 can escape to the ground.

Therefore, since the surge voltage and surge current applied to the circuit components constituting the communication unit 15 are reduced, it is not necessary to use a high-voltage component for the circuit components constituting the communication unit 15, thereby reducing the cost. Can do.

In addition, the main unit 1A of the present embodiment can measure the power for three circuits when measuring the power consumption of the load by, for example, a three-phase four-wire power distribution method, but the power can be measured by four or more circuits. When measurement is desired, the extension unit 1B is connected to the main unit 1A.

As with the main unit 1A, the extension unit 1B can measure power for three circuits, and only the required number of extension units 1B are connected to the main unit 1A. The extension unit 1B has a current measuring unit (not shown) for a plurality of circuits (for example, three circuits), and outputs a current measurement result measured by the current measuring unit to the main unit 1A.

In the main unit 1A, the power calculation unit 13 periodically fetches the current measurement value of the circuit to be measured from the extension unit 1B, and the measurement target is based on the current measurement value and the voltage value measured by the voltage measurement unit 12. Data such as power consumption and power consumption of the circuit is obtained by calculation.

Then, when the power calculation unit 13 calculates data such as power consumption and power consumption of the circuit that is the measurement target of the extension unit 1B, the measurement result is sent to the memory card I / F unit 14, the communication unit 15, and the display unit. 16 and so on.

The circuit configurations of the main unit 1A and the extension unit 1B are as described above, and the structure of the main unit 1A and the extension unit 1B will be described below with reference to FIGS. In the following description, unless otherwise specified, the vertical and horizontal directions are defined in the state of being mounted in the panel (that is, the direction shown in FIG. 4A), and the right side in FIG. That is, the longitudinal direction of the power measuring instrument (the main unit 1A and the extension unit 1B) is the left-right direction in FIG. 4A, and the width direction of the power measuring instrument is the up-down direction in FIG. The thickness direction is the left-right direction of FIG.

The main unit 1A includes, as circuit elements, a current measurement unit 11, a voltage measurement unit 12, a power calculation unit 13, a memory card interface unit 14, a communication unit 15, a display unit 16, and a power supply circuit unit 17. , A gap arrester 18, connection terminals T11 to T13, T15 to T17, and a connector CN11.

In the main unit 1A, the circuit elements are mounted on the circuit boards (the first circuit board B1 and the second circuit board B2).

The main unit 1A includes a container body 50 that stores circuit boards (first circuit board B1 and second circuit board B2) on which circuit elements are mounted. The vessel 50 is not essential.

The container 50 of the main unit 1A is configured by combining a body 51 and a cover 52 each made of a synthetic resin molded product.

The body 51 is formed in a rectangular box shape whose front side is open. The cover 52 is formed in a substantially box shape with an open rear side, and is attached to the front side of the body 51 so as to close the opening of the body 51. The protrusions 51e provided on the upper side surface and the lower side surface of the body 51 are fitted into the through holes 52c of the cover 52, so that the body 51 and the cover 52 are coupled (see FIGS. 4 and 7). ).

On the front surface of the cover 52 (the right surface in FIG. 5),

step portions

54 and 55 are provided on both sides in the width direction (vertical direction), and a trapezoidal shape is provided so as to project forward between the

step portions

54 and 55. The protrusion 53 is provided.

As shown in FIG. 5, a rectangular groove 51a extending in the left-right direction is provided near the center in the up-down direction on the back surface of the body 51 (left surface in FIG. 5). A rail member (for example, a rail member standardized by the DIN standard or the like) for mounting an internal unit (for example, a main switch or a branch switch) is inserted into the rectangular groove 51a.

The upper end face of the rectangular groove 51a is provided with a claw 51b that is engaged with the upper piece of the rail member. On the other hand, a claw 56a provided at the upper end of the latch piece 56 projects from the lower end surface of the rectangular groove 51a. The latch piece 56 is provided so as to be movable in the vertical direction with respect to the body 51, and always receives an upward elastic force by a spring portion (not shown).

Therefore, in a state where the rail member is inserted into the rectangular groove 51a, the claw 51b is locked to the upper piece of the rail member, and the claw 56a of the latch piece 56 is locked to the lower piece of the rail member. The container 50 is attached to the rail member.

The lower part of the latch piece 56 projects downward from the lower end surface of the container body 50, and when the operator pulls the lower part of the latch piece 56 downward, the claw 56a is located inside the lower end face of the rectangular groove 51a. Be drawn into. Thereby, since the latching state of the nail | claw 56a and a rail member is cancelled | released, the container 50 can be removed from a rail member.

As shown in FIG. 3, a first circuit board B1 and a second circuit board B2 are accommodated inside the container body 50. The high-power first circuit board B 1 is housed in the body 51, and the low-power second circuit board B 2 is housed in the cover 52.

That is, the container 50 includes a first case (the body 51 in the present embodiment) that houses the first circuit board B1, and a second case (the cover 52 in the present embodiment) that houses the second circuit board B2. Prepare. The first case (body 51) has a first opening that exposes the first surface (the upper surface in FIG. 3) of the first circuit board B1. The second case (cover 52) has a second opening that exposes the second surface (the lower surface in FIG. 3) of the second circuit board B2. The second case (cover 52) is attached to the first case (body 51) so that the second opening faces the first opening.

Of the connection terminals T11 to T13, T15 to T17 and the connector CN11 described above, the connection terminals T11 to T13 are connected to the first circuit board B1 of the high electrical system, and the connection terminals T15 to T17 and the connector CN11 are connected to the second circuit board B2 of the weak electrical system. Are implemented respectively.

That is, since the connection terminals T11 to T13 are included in the high-power circuit together with the power supply circuit unit 17 and the power measurement unit 10, they are mounted on the first circuit board B1. The connection terminals T15 to T17 and the connector CN11 are mounted on the second circuit board B2 because they are included in the low-power circuit together with the communication unit 15. The light electrical circuit further includes a memory card 1 / F unit 14 and a display unit 16.

An electric wire is inserted into the connection terminals T11 and T13 through a rectangular hole 51c opened on the lower surface of the body 51, and an electric wire is inserted into the connection terminal T12 through a rectangular hole 51d opened on the lower surface of the body 51.

The terminal screws of the connection terminals T11 to T13 are exposed to the front side from the through

holes

55a and 55b provided in the lower step portion 55 of the cover 52, and are screwed with a screwdriver inserted through the through

holes

55a and 55b. By tightening, the electric wires are fastened to the connection terminals T11 to T13.

In addition, the communication line CB5 and the shield line CB6 are inserted into the connection terminals T15 and T16 through the through hole 52a for electric wire insertion provided on the upper side surface of the cover 52.

The terminal screws of the connection terminals T15 and T16 are exposed to the front side from the through holes 54a provided on the front surface of the stepped portion 54, and are tightened with a screwdriver inserted from the through holes 54a. An electric wire is fastened to the connection terminals T15 and T16.

Further, the output line of the current transformer 11a is inserted into each connection terminal T17 through a through hole 52b for inserting an electric wire provided on the upper side surface or the lower side surface of the cover 52.

The terminal screw of each connection terminal T17 is exposed to the front side from the through hole 54b of the step portion 54 or the through hole 55c of the step portion 55, and is tightened with a screwdriver inserted from the through

hole

54b or 55c. As a result, the output line is fastened to the connection terminal T17.

In the present embodiment, twelve connection terminals T17 are arranged in the upper step portion 54, and six connection terminals T17 are arranged in a row in a group of six connection terminals T17 in the lower step portion 55. Three connectors CN11 are arranged side by side with the six connection terminals T17 arranged together. Then, six wire connection portions of the connection terminal T17 are exposed from each through hole 52b, and six terminal screws of the connection terminal T17 are exposed from the through

holes

54b and 55c, and six connection terminals T17. The three connectors CN11 are exposed side by side.

Further, the DIP switch 19 for setting addresses and the light emitting diodes LD1 to LD4 for performing various displays are mounted on the second circuit board B2.

The dip switch 19 is exposed to the front surface side from a through hole 53b provided on the front surface of the protruding portion 53.

The light emitted from the light emitting diodes LD1 to LD4 is emitted forward from a through hole 53c provided in the front surface of the protruding portion 53.

Further, a through hole 53d for exposing the card slot SL1 of the memory card I / F portion 14 is also provided on the front surface of the protruding portion 53.

Next, the structure of the extension unit 1B will be described. The container 60 of the extension unit 1B is configured by connecting a body 61 and a cover 62 each made of a synthetic resin molded product. The body 61 is formed in a rectangular box shape whose front side is open. The cover 62 is formed in a substantially box shape with an open rear side, and is attached to the front side of the body 61 so as to close the opening of the body 61. The protrusions 61c provided on the upper side surface and the lower side surface of the body 61 are respectively fitted into the through holes 62b of the cover 62, so that the body 61 and the cover 62 are coupled to each other (see FIGS. 4 and 8). ).

On the front surface of the cover 62,

step portions

64 and 65 are provided on both sides in the vertical direction, and a table-like protruding portion 63 is provided between the step portion 64 and the step portion 65 so as to protrude forward.

Further, as shown in FIG. 6, a rectangular groove 61a extending in the left-right direction is provided on the back surface of the body 61 in the vicinity of the center in the up-down direction.

The upper end surface of the rectangular groove 61a is provided with a claw 61b that is engaged with the upper piece of the rail member (not shown) described above. A claw 66a provided at the upper end of the latch piece 66 protrudes from the lower end surface of the rectangular groove 61a. The latch piece 66 is provided so as to be movable in the vertical direction with respect to the body 61 and always receives an upward elastic force by a spring portion (not shown).

Therefore, in a state where the rail member is inserted into the rectangular groove 61a, the claw 61b is locked to the upper piece of the rail member, and the claw 66a of the latch piece 66 is locked to the lower piece of the rail member. The container 60 is attached to the rail member.

The lower portion of the latch piece 66 protrudes downward from the lower end surface of the container body 60. When the operator pulls the lower portion of the latch piece 66 downward, the claw 66a is located inside the lower end surface of the rectangular groove 61a. Be drawn into. Thereby, since the latching state of the nail | claw 66a and a rail member is cancelled | released, the container 60 can be removed from a rail member.

Also, two slits 61d opened at the left end are formed on the upper and lower side walls of the body 61, and a flexible piece 61e is provided between the two slits 61d.

The right end of the flexible piece 61e is cantilevered on the side wall of the body 61, and the left end of the flexible piece 61e can be bent in the vertical direction. A claw 61f that projects outward is provided at the left end of the flexible piece 61e.

Further, on the right side surface of the vessel body 60, grooves 61g are provided on both sides in the vertical direction. On the right side surface of the main body 50 of the main unit 1A, grooves (not shown) similar to those of the extension unit 1B are provided on both sides in the vertical direction.

Thus, the main unit 1A and the extension unit 1B are connected to each other by locking the claw 61f of the extension unit 1B in the groove of the main unit 1A while being attached to the rail member. Further, the extension units 1B are also connected to each other by engaging the claws 61f provided on one extension unit 1B with the groove 61g of the other extension unit 1B in a state where each of the extension units 1B is attached to the rail member. .

A substrate (not shown) on which circuit components such as a current measuring unit are mounted is accommodated in the container body 60. As with the main unit 1A, the current measurement unit of the extension unit 1B includes two connection units (connection terminal T21 and connector CN21) to which two types of current transformers 11a having different measurement ranges can be connected.

And the current transformer selected according to the magnitude of the load current is connected to the corresponding connection section in the current measurement section of the extension unit 1B, and the current value to be measured is measured. In the present embodiment, three sets of connection terminals T21 and connector CN21 are set as one set so that three circuits (in the case of three-phase four-wire power distribution) can be measured with one extension unit 1B. A connection terminal T21 and a connector CN21 are provided in the extension unit 1B.

The connection terminal T21 is constituted by a screw terminal device. Twelve connection terminals T21 are provided in the upper step portion 54 of the container body 60, and six connection terminals T21 are provided in the lower step portion 65. It is arranged in a row as a group. Three connectors CN21 are arranged side by side with the six connection terminals T21 arranged together.

And the electric wire connection part of the connection terminal T21 is exposed from the through hole 62a for electric wire insertion provided in the upper surface or the lower surface of the cover 62, and the output cable of the current transformer 11a passes through the through hole 62a. Is inserted into the wire connection portion of the connection terminal T21.

Further, six terminal screws of the connection terminal T21 are exposed from the through hole 64a of the stepped portion 64 or the through hole 65a of the stepped portion 65, and the terminal screws are screwed with a screwdriver inserted from the through hole 64a or the through hole 65a. By tightening, the output cable is fastened to the connection terminal T21.

From the through

holes

64a and 65a, three connectors CN21 are exposed alongside the six connection terminals T21, and a plug-type connector (not shown) provided on the output cable of the current transformer 11a is a connector. Connected to CN21.

2. Operation of Power Measuring Instrument The power measuring instrument of the present embodiment has the above-described configuration, and a power cable CB1 from an external power source is connected to the connection terminal T11. The cable CB2 is connected to the connection terminal T12, and the voltage of the circuit to be measured is input to the voltage measurement unit 12.

The main unit 1A is provided with a plurality of sets of connection terminals T17 and connectors CN11 for current measurement, and a current transformer 11a corresponding to the circuit current to be measured is selected, and the corresponding connection terminal T17 or connector CN11 is selected. Connected to.

The power calculation unit 13 takes in the measurement results of the current measurement unit 11 and the voltage measurement unit 12 at a predetermined timing, obtains power consumption and power consumption for each circuit, and displays them on the display unit 16.

The power calculation unit 13 outputs the measurement result to the memory card I / F unit 14 and stores the measurement result in the memory card MC1.

When the extension unit 1B is connected to the main unit 1A, the power calculation unit 13 takes in the measurement current of each circuit from the extension unit 1B and uses the measurement current and the measurement result of the voltage measurement unit 12 to consume. Find the amount of power.

And the electric power calculating part 13 displays the measurement result of the measuring object by the extension unit 1B on the display part 16, or memorize | stores it in the memory card MC1.

When the management device 100 is connected to the main unit 1A, the main unit 1A transmits the history data of the measurement results stored in the memory card MC1 periodically or in response to a request from the management device 100. To the management apparatus 100. Based on the measurement result transmitted from the main unit 1A, the management device 100 can grasp the power consumption change trend due to the load.

3. Features of Power Measuring Device As described above, the power measuring device of this embodiment includes a power measuring unit (consisting of a current measuring unit 11, a voltage measuring unit 12, and a power calculating unit 13), a communication unit 15, and a power supply circuit. The unit 17 includes a connection terminal T13 that is a first ground terminal, and a connection terminal T16 that is a second ground terminal. The power measuring unit measures power consumption by the load. The communication unit 15 outputs the measurement result of the power measurement unit to an external device (for example, the management device 100) connected via the communication line CB5. The power supply circuit unit 17 receives power supply from an external power supply (for example, commercial AC power supply AC) and supplies operating power to the power measurement unit and the communication unit 15. A ground line CB3 for protective grounding of the power supply circuit unit 17 is connected to the connection terminal T13 which is the first ground terminal. The connection terminal T16 as the second ground terminal is provided for connecting the shield line CB6 that electromagnetically shields the communication line CB5. The connection terminal T13, which is the first ground terminal, and the connection terminal T16, which is the second ground terminal, are gap-coupled via a discharge gap (consisting of the gap arrester 18 in this embodiment).

That is, it can be said that the power meter of the present embodiment has the following first feature. In the first feature, the power meter includes a power measuring unit 10 that measures power, a communication terminal (connection terminal) T15 used for connection to the communication line CB5, and a communication line CB5 connected to the communication terminal 15. A first grounding terminal T13 used for connecting the communication unit 15 that outputs the value of the power measured by the power measuring unit 10 to the ground line CB3 for grounding the power meter, and the communication line CB5 are electromagnetically connected. A surge protection means (gap arrester 18 in the example shown in FIG. 1) connected between the second ground terminal T16 used for connection with the shielded shield line CB6 and the first ground terminal T13 and the second ground terminal T16. And).

Further, it can be said that the power measuring instrument of the present embodiment has the following second feature in addition to the first feature. In the second feature, the surge protection means is configured to conduct between the first ground terminal T13 and the second ground terminal T16 when a surge occurs. Note that the second feature is an arbitrary feature regarding the power measuring instrument of the present embodiment.

Further, it can be said that the power measuring instrument of the present embodiment has the following third feature in addition to the first or second feature. In the third feature, the power meter includes a power supply terminal T11 used for connection to a power supply line CB1 from an external power supply (commercial AC power supply AC in the present embodiment), and a power supply line CB1 connected to the power supply terminal T11. And a power supply circuit unit 17 that feeds power to the power measurement unit 10 and the communication unit 15 based on the power received from the external power source. The first connection terminal T13 is connected to the power supply circuit unit 17. Note that the third feature is an arbitrary feature regarding the power measuring instrument of the present embodiment.

As a result, even when no shield wire is connected to the connection terminal T16 (the communication unit 15 is not grounded), when static electricity is applied to the connection terminal T15 or T16, the discharge gap becomes conductive, so that the first Static electricity can be released to the ground via the ground terminal. Therefore, the circuit components constituting the communication unit 15 can be protected from static electricity, and components having a low withstand voltage can be used for the circuit components constituting the communication unit 15, so that the cost can be reduced.

As described above, according to the power measuring instrument of the present embodiment, static electricity is applied to the terminal (connection terminal T15) to which the communication line CB5 is connected while the shield line CB6 is not connected to the second ground terminal (connection terminal T16). When added, the discharge gap becomes conductive, and static electricity can be released from the first ground terminal (connection terminal T13) to the ground, so that the circuit components constituting the communication unit 15 can be protected from static electricity.

In this embodiment, a ground wire for protective grounding of the power supply circuit unit 17 is connected to the connection terminal T13 which is the first ground terminal. However, the first ground terminal may be used for grounding the power measuring unit 10. Good. That is, it is only necessary that a grounding wire for protective grounding at least one of the power supply circuit unit 17 and the power measuring unit 10 is connected to the first grounding terminal. If it is to do. That is, the first connection terminal T13 may be connected to the power measurement unit 10 (particularly the voltage measurement unit 12) instead of the power supply circuit unit 17. Alternatively, the first connection terminal T13 may be connected to the power supply circuit unit 17 and the power measurement unit 10 (particularly the voltage measurement unit 12).

That is, the power meter of the present embodiment may have the following fourth feature in addition to any one of the first to third features. In the fourth feature, the first connection terminal T 13 is connected to the power measurement unit 10.

In the present embodiment, the discharge gap is a gap arrester. According to the present embodiment, the discharge gap is configured by the gap arrester 18, and the discharge gap can be realized with parts having good availability.

That is, it can be said that the power meter of the present embodiment has the following fifth feature in addition to any one of the first to fourth features. In a fifth feature, the surge protection means is a surge protection device. Note that the fifth feature of the power measuring instrument of the present embodiment is an arbitrary feature.

Moreover, it can be said that the power meter of the present embodiment has the following sixth feature in addition to the fifth feature. In a sixth feature, the surge protection device is a gap arrester. Note that the sixth feature is an arbitrary feature regarding the power measuring instrument of the present embodiment. Here, the surge protection device is preferably a gap arrester, but may be a gapless arrester.

Further, instead of configuring the discharge gap with the gap arrester 18, for example, the discharge gap may be configured with a pattern gap formed on the first circuit board B1, and the discharge gap can be realized at low cost.

In other words, the first modification of the power measuring instrument of the present embodiment is a weak circuit system including the first circuit board B1 on which the high power circuit including the power measuring unit 10 and the power supply circuit unit 17 is mounted, and the communication unit 15. And a second circuit board B2 on which a circuit is mounted. The discharge gap is a pattern gap 25 formed in one of the first circuit board B1 and the second circuit board B2.

In the first modification, the surge protection means is the pattern gap 25. As shown in FIG. 9, the pattern gap 25 is composed of a first conductive layer 251 and a second conductive layer 252 formed on the first circuit board (B1) so as to face each other with a predetermined distance Dg.

The first conductive layer 251 is electrically connected to the first ground terminal T13 mounted on the first circuit board B1. The second conductive layer 252 is electrically connected to the second ground terminal T16 mounted on the second circuit board B2 using a cable or the like.

The predetermined interval Dg is set so that the first conductive layer 251 and the second conductive layer 252 are electrically connected when a surge occurs. That is, the predetermined interval Dg is selected so that a discharge occurs between the first conductive layer 251 and the second conductive layer 252 when a surge occurs. In other words, it is determined according to a voltage value or a current value that causes dielectric breakdown between the first conductive layer 251 and the second conductive layer 252.

That is, the pattern gap 25 is a conductor pattern formed on the substrate so as to face each other with a predetermined distance Dg. The pattern gap 25 may be formed on the second circuit board B2 on which a circuit including the communication unit 15 is mounted, and is formed on at least one of the first circuit board B1 and the second circuit board B2. The discharge gap may be constituted by the pattern gap.

That is, it can be said that the first modification of the power measuring instrument of the present embodiment has the following seventh feature in addition to any one of the first to fourth features. In the seventh feature, the power meter includes circuit boards (B1, B2) on which the first ground terminal T13 and the second ground terminal T16 are mounted. The surge protection means includes a first conductive layer 251 connected to the first ground terminal T13 and a second conductive layer 252 connected to the second ground terminal T16. The first conductive layer 251 and the second conductive layer 252 are formed on the circuit boards (B1, B2) so as to face each other with a predetermined distance Dg. The predetermined distance Dg is set so that the first conductive layer 251 and the second conductive layer 252 are electrically connected when a surge occurs. Note that the seventh feature is an arbitrary feature regarding the power measuring instrument of the present embodiment.

Moreover, it can be said that the 1st modification of the electric power measuring device of this embodiment has the following 8th characteristics in addition to the 7th characteristic. In an eighth feature, the circuit board includes a first circuit board B1 and a second circuit board B2. The first ground terminal T13 is mounted on the first circuit board B1. The second ground terminal T16 is mounted on the second circuit board B2. The first conductive layer 251 and the second conductive layer 252 are formed on either the first circuit board B1 or the second circuit board B2. Note that the eighth feature of the power measuring instrument of this embodiment is an arbitrary feature.

In the present embodiment, the circuit board is composed of two substrates, the first circuit substrate B1 and the second circuit substrate B2, but may be composed of one substrate.

Further, as shown in FIG. 10, the second modification of the power measuring instrument of the present embodiment includes a power measuring unit (consisting of a current measuring unit 11, a voltage measuring unit 12, and a power calculating unit 13) and a power supply circuit unit 17. Including a first circuit board B1 on which a circuit (high-electric circuit) including the second circuit board B2 on which a circuit (light-electric circuit) including the communication unit 15 is mounted is provided. The container body 50 for housing the first circuit board B1 and the second circuit board B2 is configured by combining a body 51 and a cover 52. The first circuit board B1 is accommodated in one of the body 51 and the cover 52 (the body 51 in the present embodiment), and the second circuit board B2 is disposed in the other of the body 51 and the cover 52 (the cover 52 in the present embodiment). Is stored. The first circuit board B1 and the second circuit board B2 are provided with

conductive protrusions

23 and 24 that face each other with a predetermined gap in a state where the body 51 and the cover 52 are assembled. The

protrusions

23 and 24 form a discharge gap.

In the second modification, instead of the gap arrester 18, as shown in FIG. 10, the body 51 and the cover 52 are assembled to the first circuit board B1 and the second circuit board B2 through a predetermined gap.

Conductive protrusions

23 and 24 are provided opposite to each other. In other words, in the second modification, the surge protection means includes the first protrusion 23 and the second protrusion 24 having conductivity, which are arranged to face each other with a predetermined distance Lg.

The first protrusion 23 is disposed on a surface (first surface, upper surface in FIG. 10) of the first circuit substrate B1 that faces the second circuit substrate B2. The protrusion (first protrusion) 23 provided on the first circuit board B1 is electrically connected to the connection terminal T13 that is the first ground terminal via the wiring pattern 20.

The second protrusion 24 is disposed on the surface (second surface, the lower surface in FIG. 10) facing the first circuit substrate B1 in the second circuit substrate B2. The protrusion (second protrusion) 24 provided on the second circuit board B2 is electrically connected to the connection terminal T16, which is the second ground terminal, via the wiring pattern 22.

Thus, the connection terminal T13 serving as the first ground terminal and the connection terminal T16 serving as the second ground terminal are gap-coupled via the discharge gap formed by the

protrusions

23 and 24.

That is, it can be said that the second modification of the power measuring instrument of the present embodiment has the following ninth feature in addition to any one of the first to fourth features. In the ninth feature, the power meter includes a first circuit board B1 having a first surface (upper surface in FIG. 10) and a second circuit board having a second surface (lower surface in FIG. 10) opposite to the first surface. B2. The first ground terminal T13 is mounted on the first circuit board B1. The second ground terminal T16 is mounted on the second circuit board B2. The surge protection means includes a first protrusion 23 and a second protrusion 24. The first protrusion 23 is disposed on the first surface of the first circuit board B1 and is electrically connected to the first ground terminal T13. The second protrusion 24 is disposed on the second surface of the second circuit board B2 so as to face the first protrusion 23 with a predetermined distance Lg, and is electrically connected to the second ground terminal T16. The The predetermined interval Lg is set so that the first protrusion 23 and the second protrusion 24 are electrically connected when a surge occurs. Note that the ninth feature is an arbitrary feature regarding the power measuring instrument of the present embodiment.

As a result, even when the shield wire CB6 is not connected to the connection terminal T16 (the communication unit 15 is not grounded), if static electricity is applied to the connection terminal T15 or T16, dielectric breakdown occurs between the

protrusions

23 and 24. Occurs, and the

protrusions

23 and 24 are electrically connected.

Therefore, the static electricity applied to the communication unit 15 can be released from the first ground terminal T13 to the ground, and the surge voltage and surge current applied to the circuit components constituting the communication unit 15 can be reduced. Therefore, it is possible to use a component having a low withstand voltage as the circuit component constituting the communication unit 15, so that the cost can be reduced.

Moreover, it can be said that the 2nd modification of the electric power measuring device of this embodiment has the following 10th characteristics in addition to the 9th characteristic. In the tenth feature, the power meter includes a first case (body 51 in the present embodiment) that houses the first circuit board B1 and a second case (cover 52 in the present embodiment) that houses the second circuit board B2. And). The first case has a first opening (the upper opening in FIG. 10) that exposes the first surface of the first circuit board B1. The second case has a second opening (lower opening in FIG. 10) that exposes the second surface of the second circuit board B2. The second case is attached to the first case so that the second opening faces the first opening. Note that the tenth feature is an optional feature with respect to the power meter of the present embodiment.

The gap length (predetermined interval) Lg between the tip of the projection 23 and the tip of the projection 24 is such that the first projection 23 and the second projection 24 are electrically connected when a surge occurs. Is set. That is, the predetermined interval Lg is selected so that discharge occurs between the first protrusion 23 and the second protrusion 24 when a surge occurs. In other words, the gap length Lg may be determined according to the voltage value or current value that causes dielectric breakdown between the

protrusions

23 and 24.

Claims

A power meter,
A power measurement unit for measuring power;
A communication terminal used for connection with a communication line;
A communication unit that outputs a value of power measured by the power measurement unit to the communication line connected to the communication terminal;
A first ground terminal used for connection to a ground wire for grounding the power meter;
A second ground terminal used for connection with a shielded wire that electromagnetically shields the communication line;
Surge protection means connected between the first ground terminal and the second ground terminal;
A power measuring instrument comprising:
The power measuring instrument according to claim 1, wherein the surge protection means is configured to conduct between the first ground terminal and the second ground terminal when a surge occurs.
The power measuring instrument according to claim 1, wherein the surge protection means is a surge protection device.
The power measuring instrument according to claim 3, wherein the surge protection device is a gap arrester.
A circuit board on which the first ground terminal and the second ground terminal are mounted;
The surge protection means has a first conductive layer connected to the first ground terminal, and a second conductive layer connected to the second ground terminal,
The first conductive layer and the second conductive layer are formed on the circuit board so as to face each other with a predetermined gap therebetween,
The power meter according to claim 1, wherein the predetermined interval is set so that conduction between the first conductive layer and the second conductive layer occurs when a surge occurs.
The circuit board includes a first circuit board and a second circuit board,
The first ground terminal is mounted on the first circuit board;
The second ground terminal is mounted on the second circuit board;
The power measuring instrument according to claim 5, wherein the first conductive layer and the second conductive layer are formed on one of the first circuit board and the second circuit board.
A first circuit board having a first surface;
A second circuit board having a second surface facing the first surface;
With
The first ground terminal is mounted on the first circuit board;
The second ground terminal is mounted on the second circuit board;
The surge protection means has a first protrusion and a second protrusion,
The first protrusion is disposed on the first surface of the first circuit board and is electrically connected to the first ground terminal.
The second protrusion is disposed on the second surface of the second circuit board so as to face the first protrusion with a predetermined gap, and is electrically connected to the second ground terminal. ,
The power meter according to claim 1, wherein the predetermined interval is set so that the first protrusion and the second protrusion are electrically connected when a surge occurs.
A first case for housing the first circuit board;
A second case for accommodating the second circuit board;
With
The first case has a first opening that exposes the first surface of the first circuit board;
The second case has a second opening that exposes the second surface of the second circuit board;
The power meter according to claim 7, wherein the second case is attached to the first case so that the second opening faces the first opening.
A power supply terminal used for connection with a power supply line from an external power supply;
A power supply circuit unit that feeds power to the power measurement unit and the communication unit based on power received from the external power supply through the power supply line connected to the power supply terminal;
With
The power measuring instrument according to claim 1, wherein the first connection terminal is connected to the power supply circuit unit.
The power measuring instrument according to claim 1, wherein the first connection terminal is connected to the power measuring unit.