JP7281326B2 - electricity meter - Google Patents

Description

The present invention relates to a watt hour meter.

2. Description of the Related Art Conventionally, electronic watt-hour meters are known as watt-hour meters for measuring electric energy used by consumers. An electronic watt-hour meter consists of a terminal section where terminal fittings to which distribution lines are connected, a power calculation section that calculates power, a display section that displays power consumption, and a central control section that controls each section. It is configured. The board on which the electronic parts that make up the power calculation unit, central control unit, etc. are mounted, the display unit, etc., are fixed to the housing with screws, etc., and the terminals and the board, and between the board and the display unit, are electrically connected by cables, etc. properly connected.

In the terminal portion, connection between each terminal fitting and the distribution line is usually performed by screwing. Specifically, using an attached terminal screw, the crimp terminal to which the distribution line is crimped is fastened and fixed to the terminal fitting.

Conventionally, terminal screws are generally tightened step by step by an operator using an electric screwdriver and a torque wrench. Specifically, the operator first temporarily tightens the terminal screw using an electric screwdriver. After that, the worker checks whether or not each terminal screw is loose by touching the cable of the distribution line with his/her hand. Then, the terminal screws thought to be loose are further tightened with a torque wrench. Therefore, in some cases, the terminal screws that are thought to have no looseness are only temporarily tightened.

Thus, in the conventional tightening work, confirmation of the tightening state mainly relies on the sense of the operator. However, the operator is not necessarily a skilled worker, and in that case, there is a risk that the installation of the watt-hour meter may be completed in an insufficiently tightened state without being able to notice the slight looseness. If the watt-hour meter is used with insufficient tightening of the terminal screws, the temperature of the terminals increases due to an increase in contact resistance, and the resin housing may melt or catch fire.

Patent Literature 1 describes an electric meter provided with a temperature sensor that measures the heat generation temperature of the terminal portion and the ambient temperature of the housing. In this electric meter, an abnormal state of the terminal is detected from the difference between the heat generation temperature of the terminal and the ambient temperature of the housing. However, in the configuration of Patent Document 1, the detection unit functions only when the electric meter is in use. In other words, it is impossible to detect an abnormal state of the terminal portion before the electric meter is used.

JP 2011-013067 A

An object of one embodiment of the present invention is to provide a watt-hour meter capable of detecting the state of connection between a terminal portion and a distribution line before the meter is used.

According to one embodiment of the present invention, there is provided a watt-hour meter comprising a terminal portion configured to connect a crimp terminal to a terminal fitting, wherein the terminal portion comprises an insulating space defined by a partition wall portion of an insulating housing. , a terminal fitting fixed in the insulating space, and a terminal screw that can be tightened through the opening of the terminal fitting and the crimp terminal, and the watt-hour meter includes a detection unit that detects the tightening state of the terminal screw. The detection unit includes a displacement member disposed in the insulating space so as to be able to abut against the tip of the shaft portion of the terminal screw and displaceable in the axial direction of the terminal screw according to the tightening amount of the terminal screw. An electricity meter is provided, which is formed of a non-conductive material.

1 is a front view showing a watt-hour meter according to a first embodiment of the present invention; FIG. It is a figure which shows an example of a crimp terminal. It is a figure which shows the structure of a terminal part, (A) shows the loosened state of a terminal screw, (B) shows the state in which the terminal screw was completely tightened. FIG. 4 is a schematic diagram showing the overall configuration of the detection unit according to the first embodiment, and is a diagram showing a loosened state of a terminal screw. FIG. 4 is a schematic diagram showing the overall configuration of the detection unit according to the first embodiment, and shows a state in which terminal screws are completely tightened. FIG. 10 is a schematic diagram showing the overall configuration of the detection unit according to the second embodiment, and is a diagram showing a loosened state of the terminal screw. FIG. 10 is a schematic diagram showing the overall configuration of the detection unit according to the second embodiment, and shows a state in which terminal screws are completely tightened.

Hereinafter, each embodiment of the present invention will be described with reference to the drawings. Note that the following description is merely an example, and is not intended to limit the technical scope of the present invention to the following embodiments. In addition, in the drawings, the same or corresponding components are denoted by the same reference numerals, and redundant explanations are omitted. In the following description, terms indicating directions such as "up" and "down" are used for convenience in order to facilitate understanding of the present invention, and are not intended to limit the present invention.

[First embodiment]
FIG. 1 is a front view showing an electronic watt-hour meter 1000 as an example of the watt-hour meter according to the first embodiment. The electronic watt-hour meter 1000 is attached to the wall surface of a building or a general house in the illustrated direction. The electronic watt-hour meter 1000 of the first embodiment includes a terminal section 100 configured to connect a distribution line (not shown) to a terminal fitting 108 by tightening an attached terminal screw 110, and a central processing section 102 (FIG. 1). ), and a display unit 112 controlled by the central processing unit 102 . In the illustrated example, the electronic watt-hour meter 1000 is of a single-phase three-wire type, but the type of the electronic watt-hour meter 1000 is not particularly limited. Further, in the first embodiment, the liquid crystal display section is described as the display section 112, but the display section 112 is not limited to the liquid crystal display section.

The terminals 100 include a power source side terminal portion 100A (1S, 2S, 3S) to which the distribution line from the power supply facility is connected, and a load side terminal portion 100B (1L) to which the distribution line to the load in the consumer is connected. , 2L, 3L) are arranged to face each other in the vertical direction. The power-side terminal portion 100A and the load-side terminal portion 100B have an insulating space 104 electrically insulated from each other by a partition wall portion 106 of the resin housing of the electronic watt-hour meter 1000 . A terminal fitting 108 and a terminal screw 110 are disposed within each insulating space 104 . Each terminal fitting 108 is connected to a distribution line by, for example, inserting and crimping the distribution line into a cavity 122 of a crimp terminal 120 having a ring-shaped tip 118 as shown in FIG. can be performed by screwing the terminal screw 110 to the terminal fitting 108 .

FIGS. 3A and 3B are schematic partial cross-sectional views showing the configuration inside the insulating space 104 of the terminal section 100, and an electronic watt-hour meter (hereinafter referred to as a watt-hour meter) 1000 is shown in the lower part of FIG. The configuration is shown when viewed from the side. That is, in FIGS. 3A and 3B, the upper side is the front side of the watt-hour meter 1000, and the lower side is the rear side. In the terminal portion 100, the terminal fitting 108 and the nut 124 are positioned and fixed in advance in the insulating space 104 between the adjacent partition portions 106 so that the respective openings (reference numerals omitted) are aligned. Specifically, the partition wall portion 106 forms a stepped portion 126 projecting into the insulating space 104 , and the terminal fitting 108 is attached to the nut 124 arranged on the stepped portion 126 . A crimp terminal 120 is arranged between the attached terminal screw 110 and the terminal fitting 108 . Thus, the terminal screw 110 is tightened through the openings of the crimp terminal 120 , the terminal fitting 108 and the nut 124 , thereby connecting the crimp terminal 120 to the terminal fitting 108 . In the figure, 128 indicates a washer, but the washer is not an essential component in this embodiment.

A recess 132 having a bottom surface 130 is formed below the stepped portion 126 . The recess 132 can receive the tip of the shank of the tightened terminal screw 110 . Also, the recess 132 can accommodate a switch portion 134 attached to the bottom surface 130 . However, the specific shape of the partition 106 is not limited to that shown in FIGS. 3(A) and 3(B). As the switch section 134, for example, a general-purpose push button switch for substrate mounting can be used. The switch portion 134 forms part of a detection portion that detects the tightening state of the terminal screw 110 . The overall configuration of the detection unit will be described later with reference to FIG. 4 and the like.

FIG. 3A shows an example of the state of the terminal portion 100 before the terminal screw 110 is completely tightened (in other words, when the terminal screw 110 is in a loose state). 3A, there is a gap C between the crimp terminal 120 and the terminal fitting 108, and the tip of the shaft portion of the terminal screw 110 is not in contact with the button of the switch portion 134. In FIG. FIG. 3B shows the state of the terminal section 100 with the terminal screw 110 completely tightened. At this time, the crimp terminal 120 and the terminal fitting 108 are fixed in close contact with each other. Thus, the watt hour meter 1000 and the distribution line are connected. At this time, as shown in FIG. 3B, the tip of the shaft portion of the terminal screw 110 pushes down the button of the switch portion 134 . In the following description, "the terminal screw 110 is completely tightened" means a state in which the crimp terminal 120 and the terminal fitting 108 are brought into close contact with each other by the terminal screw 110 without fear of heat generation due to an increase in contact resistance. , and the “loose state” means a state in which the terminal screw 110 is not completely tightened. 3A and 3B each show only the configuration within one insulating space 104, each of the plurality of insulating spaces 104 of the terminal section 100 has the same configuration as shown in the drawings. are doing.

Next, the overall configuration and operation of the detector will be described with reference to FIGS. 4 and 5. FIG. The electronic watt-hour meter 1000 of the first embodiment includes a detector that detects the tightening state of the terminal screw 110 . FIG. 4 is a schematic diagram showing the overall configuration of the detection unit of electronic watt-hour meter 1000, showing a state before terminal screw 110 is completely tightened. FIG. 5 shows the terminal screw 110 fully tightened.

In the first embodiment, a detection unit including the above-described on/off switch unit 134 is provided. The switch section 134 includes a conductive movable piece 136 arranged inside a casing (not shown) and a displacement member 138 forming a button of the switch section 134 . The displacement member 138 can reciprocate in the casing so as to be able to come into contact with and separate from the movable piece 136 . Accordingly, the displacement member 138 may be biased toward the insulating space 104 (upward in FIG. 4) by, for example, a spring. Also, the displacement member 138 may be made of a non-conductive material such as resin. Displacement member 138 is operated by terminal screw 110 . Therefore, by forming the displacement member 138 from a non-conductive material, when the terminal screw 110 comes into contact with the displacement member 138, a high alternating current from the distribution line is applied to the displacement member 138 through the crimp terminal 120 and the terminal screw 110. can be prevented from being applied to

The form of the displacement member 138 is not particularly limited. In the illustrated example, the displacement member 138 is a rod-shaped member that is axially aligned with the shank of the terminal screw 110 and arranged at a position where it can come into contact with the tip of the shank of the terminal screw 110 . The displacement member 138 can be arranged to be displaceable in the axial direction of the terminal screw 110 according to the tightening amount of the terminal screw 110 (in other words, the amount of rotation or axial movement of the terminal screw 110). The displacement member 138 may protrude at least partially into the insulation space 104 .

A movable contact 140 provided at one end of the movable piece 136 is disposed so as to be capable of contacting and separating from a fixed contact 146 of a signal line 142 connected to an input port 141 of the central processing unit (CPU) 102 of the watt-hour meter 1000 . can be done. On the other hand, the other end of the movable piece 136 can always be connected to the ground terminal 148 inside the watt hour meter 1000 . A state signal indicating the tightening state of the terminal screw 110 (in other words, whether the terminal screw 110 is completely tightened) can be input to the central processing unit 102 via the signal line 142 .

Displacement member 138 and movable piece 136 of switch portion 134 can be positioned so that movable contact 140 contacts fixed contact 146 only when terminal screw 110 is completely tightened.

The signal line 142 can include a connection point 152 between the fixed contact 146 and the input port 141 and a power supply side terminal 150 inside the watt hour meter 1000 . The terminal voltage DV of the power supply side terminal 150 is equal to the DC power supply voltage supplied to the internal circuit of the central processing unit 102 . The power supply terminal 150 can be connected to the signal line 142 via the resistor 154 in order to input a voltage lower than the DC power supply voltage (hereinafter referred to as power supply voltage).

In the detection unit configured as described above, when the terminal screw 110 is in a loose state corresponding to, for example, FIG. Not connected. Therefore, the switch section 134 is in an open (off) state. At this time, the input port 141 of the central processing unit 102 receives a power supply side voltage (in other words, an open signal) as a state signal indicating the tightening state of the terminal screw 110 . At this time, the determination unit 156 of the central processing unit 102 determines that the switch unit 134 is in the open state, and displays "open" indicating the loosened state of the terminal screw 110 on the liquid crystal display unit 112 via the liquid crystal display control unit 158. "OPEN" or the like is displayed.

When the terminal screw 110 is completely tightened, as shown in FIG. 5, the movable contact 140 of the movable piece 136 is connected to the fixed contact 146 by the displacement member 138 pushed down by the tip of the shank of the terminal screw 110. . Thus, the switch section 134 is placed in a closed (on) state. At this time, the input port 141 of the central processing unit 102 is supplied with a ground side voltage (in other words, a closed signal) as a state signal indicating the tightening state of the terminal screw 110 . At this time, the determination unit 156 of the central processing unit 102 determines that the switch unit 134 is in the closed state, and notifies the liquid crystal display unit 112 via the liquid crystal display control unit 158 that the terminal screw 110 has been completely tightened. It is possible to display "CLOSE", "CLOSE", etc. to indicate the loosened state, or simply turn off the display of "OPEN", "OPEN", etc. to indicate the loosened state.

As described above, according to the first embodiment, the tightening state of the terminal screw 110 can be detected by the electrical detection section. Since the detection result can be viewed on the liquid crystal display unit 112, the operator does not need to check the tightening state of each terminal screw 110 by hand. In addition, since the tightening state can be confirmed without relying on the operator's sense, the terminal screw 110 can be securely and completely tightened. Therefore, since the watt-hour meter 1000 and the distribution line can be reliably connected when the watt-hour meter 1000 is installed, it is possible to eliminate the risk of an accident such as a fire due to abnormal heat generation caused by an increase in contact resistance. In addition, even if the terminal screw 110 is loosened after the watt-hour meter 1000 is installed, the occurrence of the loosening can be known by displaying “OPEN” or the like on the liquid crystal display section 112 .

[Second embodiment]
Next, with reference to FIGS. 6 and 7, the overall configuration and operation of the detection unit of the watt hour meter according to the second embodiment will be described. The watt-hour meter of the second embodiment can have the same configuration as the watt-hour meter 1000 of the first embodiment, except for the configuration of the detection unit described below. FIG. 6 is a schematic diagram showing the overall configuration of the detection unit according to the second embodiment, showing a state before the terminal screw 110 is completely tightened. FIG. 7 shows the terminal screw 110 fully tightened.

As shown in FIGS. 6 and 7, in the second embodiment, instead of the on/off switch section 134, a detection section having an analog output detector 170 capable of inputting a continuous voltage value to the central processing section 102 is provided. be done. In this case, an A/D conversion port can be used as the input port 143 of the central processing unit 102 . Analog output detector 170 can include a displacement member 172 , which can be constructed from a rod-shaped member similar to the first embodiment, and a conductive slider pin 174 fixed to displacement member 172 . One end 176 of the slider pin 174 is connected to a signal line 145 connected to the input port 143 of the central processing unit 102 of the watt hour meter. A connection point 152 connected via 154 may be included. A state signal indicating the tightening state of the terminal screw 110 (in other words, the degree of tightening of the terminal screw 110) can be input to the central processing unit 102 via the signal line 145 .

The other end of the slider pin 174 forms a slider portion 178 against a grounded variable resistor resistor 180 . The slider pin 174 fixed to the displacement member 172 is axially displaceable together with the displacement member 172 according to the tightening amount of the terminal screw 110 . Therefore, the resistance value of the resistor 180 can be changed by changing the position of the slider pin 174 .

In the illustrated circuit, the voltage output to the input port 143 can be expressed by the following equation.

R2 x DV/(R1 + R2)
Here, DV indicates the DC power supply voltage of the power supply side terminal 150 . R 1 represents the resistance value of resistor 154 and R 2 represents the variable resistance value of resistor 180 . The variable resistance value R2, for example, exhibits a minimum value when the displacement amount of the displacement member 172 is 0, and a maximum value when the displacement member 172 is displaced to the maximum (that is, when the terminal screw 110 is completely tightened). Can be configured to indicate a value.

6 and 7, the variable resistance value R2 is 0 when the displacement amount of the displacement member 172 is 0 (FIG. 6), and the variable resistance value R2 is 0 when the terminal screw 110 is completely tightened (FIG. 7). The resistance value R2 is the maximum resistance value R2max.

In this case, when the terminal screw 110 is completely tightened, the voltage value output to the input port 143 is
R2max x DV/(R1 + R2max)
can be expressed as

When the terminal screw 110 is tightened to such an extent that the displacement member 172 is displaced by, for example, half of its maximum displacement amount, the voltage value output to the input port 143 is
0.5*R2max*DV/(R1+0.5*R2max)
can be expressed as

Also, when the displacement amount of the displacement member 172 is 0, the voltage value output to the input port 143 is 0 because the value of R2 is 0.

The voltage value output from the analog output detector 170 in this manner is A/D converted at the input port 143 and input to the central processing unit 102 . The determination unit 156 of the central processing unit 102 can display the tightening state of the terminal screw 110 on the liquid crystal display unit 112 via the liquid crystal display control unit 158 based on the input value. The display can be an analog display corresponding to the analog output of analog output detector 170 . However, by appropriately setting the threshold value of the voltage value in advance, the determination unit 156 of the central processing unit 102 can be configured to perform stepwise display, such as displaying the tightening state in four steps.

As described above, in the second embodiment, the tightening state of the terminal screw 110 can be detected by the electrical detection section, as in the first embodiment. Since the detection result can be viewed on the liquid crystal display unit 112, the operator does not need to check the tightening state of each terminal screw 110 by hand. In addition, since the tightening state can be confirmed without relying on the operator's sense, the terminal screw 110 can be securely and completely tightened. Therefore, since the watt-hour meter and the distribution line can be reliably connected when the watt-hour meter is installed, it is possible to eliminate the risk of an accident such as a fire due to abnormal heat generation caused by an increase in contact resistance. Further, in the second embodiment, since the analog output detector 170 is used as the detector, the degree of tightening of the terminal screw 110 can be displayed. Therefore, if the terminal screw 110 becomes loose after the watt-hour meter is installed, it is possible to alert the operator during periodic inspection or the like.

In addition, in each embodiment, the liquid crystal display unit 112 may include a reporting unit using voice means. In this case, for example, in the first embodiment, the notification unit may be configured to emit a warning sound only when an open signal is input to the central processing unit 102 . Also, in each embodiment, the watt-hour meter does not necessarily have to be an electronic watt-hour meter. In this case, a display device may be provided separately from the power meter so that the tightening state of the terminal screw 110 can be confirmed by the display device.

Although the embodiment of the present invention has been described above, the above-described embodiment of the present invention is for facilitating understanding of the present invention, and does not limit the present invention. The present invention may be modified and improved without departing from its spirit, and the present invention includes equivalents thereof. In addition, any combination or omission of each component described in the claims and the specification is possible within the range that at least part of the above problems can be solved or at least part of the effect is achieved. is.

The present invention includes the following aspects.
1. A watt-hour meter comprising a terminal section configured to connect a crimp terminal to a terminal fitting,
The terminal portion includes an insulating space defined by a partition wall portion of the insulating housing, a terminal fitting fixed within the insulating space, and a terminal screw that can be tightened through openings of the terminal fitting and the crimp terminal,
The watt-hour meter is equipped with a detector that detects the tightening state of the terminal screw.
The detection unit includes a displacement member arranged in the insulating space so as to be able to abut against the tip of the shaft portion of the terminal screw and displaceable in the axial direction of the terminal screw according to the amount of tightening of the terminal screw,
The electricity meter, wherein the displacement member is made of a non-conductive material.
2. 1 above. The watt-hour meter according to
the electricity meter is an electronic electricity meter comprising a central processing unit and a display controlled by the central processing unit;
The power meter, wherein the central processing unit has an input port for inputting the detection result of the detection unit, and is configured to control the display unit based on the detection result.
3. 2. above. The watt-hour meter according to
The power meter, wherein the detection unit includes a movable piece having a movable contact that can be brought into and out of contact with a fixed contact of the signal line connected to the input port of the central processing unit, and the movable piece is driven by displacement of the displacement member.
4. 2. above. The watt-hour meter according to
The detection unit includes a slider pin fixed to the displacement member and a resistor, one end of the slider pin is connected to a signal line connected to the input port, and the other end of the slider pin is a movable contact to the resistor. form a watt-hour meter.

INDUSTRIAL APPLICABILITY The present invention can be widely applied to watt-hour meters configured to connect crimp terminals to terminal fittings with terminal screws.

C clearance 100 terminal portion 100A power supply side terminal portion 100B load side terminal portion 102 central processing portion 104 insulating space 106 partition wall portion 108 terminal fitting 110 terminal screw 112 liquid crystal display portion 118 tip portion 120 crimp terminal 122 hollow portion 124 nut 126 stepped portion 128 Washer 130 Bottom surface 132 Recess 134 Switch part 136 Movable piece 138 Displacement member 140 Movable contact 141, 143 Input port 142, 145 Signal line 146 Fixed contact 148 Ground side terminal 150 Power supply side terminal 152 Connection point 154 Resistor 156 Judgment part 158 Liquid crystal display Control Unit 170 Analog Output Detector 172 Displacement Member 174 Slider Pin 176 One End 178 Other End 180 Resistor 1000 Electronic Electricity Meter

Claims (1)

A watt-hour meter comprising a terminal section configured to connect a crimp terminal to a terminal fitting,
The terminal portion includes an insulating space defined by a partition wall portion of an insulating housing, a terminal fitting fixed within the insulating space, and a terminal screw that can be tightened through openings of the terminal fitting and the crimp terminal. ,
The electricity meter includes a detection unit that detects a tightening state of the terminal screw,
the detection unit includes a displacement member arranged in the insulating space so as to be able to abut against the tip of the shaft portion of the terminal screw and displaceable in the axial direction of the terminal screw according to the tightening amount of the terminal screw;
The displacement member is made of a non-conductive material ,
The watt-hour meter is an electronic watt-hour meter comprising a central processing unit and a display unit controlled by the central processing unit,
The central processing unit has an input port for inputting the detection result of the detection unit, and is configured to control the display unit based on the detection result,
The detection unit includes a slider pin fixed to the displacement member and a resistor, one end of the slider pin is connected to a signal line connected to the input port, and the other end of the slider pin is A power meter forming a movable contact for the resistor .

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