JP7248382B2 - electronic electricity meter - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electronic watt-hour meter having a function of displaying the state of a load.

2. Description of the Related Art Conventionally, an electronic watt-hour meter of this type is disclosed, for example, in Japanese Unexamined Patent Application Publication No. 2002-200013. In this electronic watt-hour meter, when all-phase power, which is the total power of all phases being measured, flows in the opposite direction from the load side to the power supply side, the reverse current mark lights up on the status display section. Furthermore, the reverse current mark blinks at a speed corresponding to the magnitude of the reverse direction all-phase power to indicate the state of the load. In addition, the direction of each phase power is determined, and when the 1-side power is in the opposite direction, "1" is lit on each phase reverse current display unit, and when the 3-side power is in the opposite direction, "3" is lit. , indicates the phase in which the connection error occurs.

However, in the electronic watt-hour meter disclosed in Patent Document 1, when the power factor of the load is extremely low in the actual usage state, even though the wiring is normal, "1" or "3" is displayed along with the operation lighting. ” lights up, giving the user the impression that the connection is incorrect. For this reason, the electronic watt-hour meter disclosed in Patent Document 2 includes a power factor state monitoring unit that monitors the value of the power factor of each phase power. When the value is between 0 and 0.5, the "1" and "3" of each phase reverse current display section are extinguished. Therefore, even when the power factor is between 0 and 0.5, the reverse current display for each phase is extinguished to indicate that there is no misconnection.

Japanese Patent No. 4986931 Japanese Patent No. 5322981

However, in the electronic watt-hour meter disclosed in Patent Document 2, when the value of the power factor is 0 to 0.5, the reverse current display for each phase is turned off, so the detailed state of the load can be displayed. unable to comprehend. For this reason, even if it turns out that the wiring is correct, it is impossible to accurately grasp the current status of what kind of load is currently connected to the electronic watt-hour meter, and it is difficult to deal with it. is assumed.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems. A power flow direction discriminating unit that discriminates as a power flow, and the power flow direction discriminating result of the active power and reactive power of each phase by this power flow direction discriminating unit , for each phase of phase 1, phase 2, and phase 3, the active power A pair of vertically aligned "+" and "-" symbols and a vertically aligned pair of "+" and "-" symbols for reactive power are arranged horizontally, and each "+" in each phase The symbol and each "-" symbol are arranged in a horizontal line, and each "+" symbol is highlighted when the power flow direction determination result is forward flow, and each "-" symbol is highlighted when it is reverse power flow. The active power of each phase is displayed by the load status display section and the power flow direction discrimination section, which always displays as a combination of forward power flow or reverse power flow discrimination results arranged for each phase regardless of the power factor value of the load. and a display control section for controlling the display of the load state display section based on the power flow direction determination result for reactive power.
Also, a power calculation unit that calculates the active power and reactive power of each phase, a power flow direction determination unit that determines the power flow direction of the active power and reactive power of each phase as forward flow or reverse power flow, and this power flow direction determination unit The power flow direction discrimination results for the active power and reactive power of each phase are shown for each phase of phase 1 and phase 3 by vertically arranging "+" and "-" symbol pairs for active power, and for reactive power The pairs of "+" and "-" symbols that are aligned vertically are arranged horizontally, and each "+" symbol and each "-" symbol in each phase are arranged in a horizontal row, and the power flow direction discrimination result Each "+" symbol is highlighted when there is forward power flow, and each "-" symbol is highlighted when there is reverse power flow. The load status display unit displays the combination of forward power flow or reverse power flow determination results arranged in a row, and the load status display unit display based on the power flow direction determination results for the active power and reactive power of each phase by the power flow direction determination unit. A three-phase, three-wire electronic watt-hour meter is configured by including a display control unit that controls the .

According to this configuration, the power flow direction determining unit determines whether the power flow direction of the active power and reactive power of each phase is forward flow or reverse power flow. A combination of forward flow or reverse flow discrimination results arranged for each phase is displayed in the section. This load status display is always displayed regardless of the value of the power factor of the load. Therefore, the current load state can be grasped in detail regardless of the power factor value of the load based on the combination of the power flow direction determination results for the active power and reactive power of each phase displayed for each phase. You will always be able to accurately grasp the current situation and quickly deal with the situation.

According to this configuration, by visually recognizing the symbol pair of "+" and "-" displayed for each phase on the load state display section and confirming which symbol is highlighted, The power flow directions for active and reactive power can be recognized at a glance. Therefore, it is possible to deal with the matter more quickly.

According to the present invention, the current load state can be determined in detail regardless of the power factor value of the load based on the combination of the power flow direction determination results for the active power and reactive power of each phase displayed for each phase. An electronic watt-hour meter is provided that can be grasped and always accurately grasps the current situation.

1 is a front view of an electronic watt-hour meter according to an embodiment of the present invention; FIG. (a) is a display example of active power W when the electronic watt-hour meter according to one embodiment is used as a normal meter, (b) is a display example of reactive power Var when it is used as a reactive meter, ( c) is a diagram showing a display example of active power W and reactive power Var when used as a composite instrument. 1 is a block diagram showing a schematic configuration of an electronic circuit configured in an electronic watt-hour meter according to an embodiment; FIG. (a) is the display mode of the power flow direction determination result when the electronic watt-hour meter according to the embodiment is a three-phase four-wire system, and (b) is the power flow direction determination when it is a three-phase three-wire system. FIG. 10(c) is a display form of the results, showing a display form indicating that phase 3 is unloaded in the case of a three-phase three-wire system. (a) is a display mode in which the voltage identified by the applied voltage identification unit is out of the predetermined range of the rated voltage when the operation signal from the load state display switch is an ON signal, and (b) is a load state display. FIG. 10 is a diagram showing a display mode in which the voltage identified by the applied voltage identification unit is not within the predetermined range of the rated voltage when the operation signal from the switch is an off signal; (a) is a display mode in which an open phase is detected in phase 3 when the operation signal from the load state display switch is an ON signal, and (b) is when the operation signal from the load state display switch is an OFF signal. 2 is a diagram showing a display mode in which an open phase is detected in phase 3. FIG. (a) is a vector diagram of voltages V1, V3 and currents I1, I3 when only pure resistors are connected to a single-phase three-wire electronic watt-hour meter; (b) is a vector diagram with only capacitors connected; (c) is a vector diagram of line voltages V12, V32 and phase currents I1, I3 when only pure resistance is connected to a three-phase three-wire electronic watt-hour meter, (d) is a vector diagram when only capacitors are connected;

Next, the form for implementing the electronic watt-hour meter according to the present invention will be described.

FIG. 1 is a front view of an electronic watt-hour meter 1 according to one embodiment of the present invention.

The electronic watt-hour meter 1 is constructed by incorporating parts such as an electronic circuit board in a rectangular parallelepiped housing. The electronic watt-hour meter 1 has a power supply terminal provided on its rear surface to which a power supply line is connected, and a load terminal to which a load device is connected. Then, the power consumed by the load equipment connected to the load terminal is measured, the result of the measurement is displayed on the front display unit 2, and a measurement pulse proportional to the power consumption is sent to the external equipment.

FIG. 2(a) shows an example of display on the display unit 2 of the active electric energy Wh [kWh] consumed by the load equipment when the electronic watt-hour meter 1 is used as an ordinary meter. FIG. 4(b) shows an example of display of the reactive power amount Varh [kvarh] on the display unit 2 when the electronic watt-hour meter 1 is used as a reactive meter. During the measuring operation of these active electric energy Wh [kWh] and reactive electric energy Varh [kvarh], the display of "operation ●" blinks at a speed proportional to the magnitude of the electric energy. FIG. 1(c) shows the active energy Wh [kWh] shown on the left side of the figure and the reactive energy Varh [kvarh] ] and are alternately displayed cyclically over time. During this cyclic display, the display of "action ● w ● var" blinks at a speed proportional to the magnitude of each of the active energy and the reactive energy. In the lower portion of the display section 2, pulse constants for two types of transmitted pulse outputs are shown.

FIG. 3 is a block diagram showing a schematic configuration of an electronic circuit configured on an electronic circuit board inside the three-phase, three-wire electronic watt-hour meter 1. As shown in FIG.

The electronic circuit board includes a power calculator 11 that calculates active power W and reactive power Var of each phase. When the phase format is a three-phase three-wire system, the line voltages V12, V32 and the phase currents I1, I3 are input to the power calculator 11, and the power consumption of the load equipment is calculated by the two-wattmeter method. That is, the product (V12·I1) of the line voltage V12 and the phase current I1 is multiplied by cos (φ+30°), which is the cosine of the phase (φ+30°) between the line voltage V12 and the phase current I1. , the active power W1 for phase 1 is calculated by the following equation (1).
W1=V12・I1・cos (φ+30°) (1)

Further, by multiplying the product (V12·I1) of the line voltage V12 and the phase current I1 by sin (φ+30°), which is the sine of the phase (φ+30°) between the line voltage V12 and the phase current I1, , the reactive power Var1 for phase 1 is calculated by the following equation (2).
Var1=V12・I1・sin (φ+30°) (2)

Also for phase 3, from the values of the line voltage V32 and the phase current I3 and the phase (φ-30°) between the line voltage V32 and the phase current I3, the active power W3 is similarly calculated by the following equation (3): , and the reactive power Var3 are calculated by the following equation (4).
W3=V32・I3・cos (φ-30°) …(3)
Var3=V32・I3・sin (φ-30°) …(4)

The power flow direction determination unit 12 determines the power flow direction of the active powers W1 and W3 and the reactive powers Var1 and Var3 of each phase. That is, the power flow directions of active power W1 and reactive power Var1 are determined from the respective directions of line voltage V12 and phase current I1 for phase 1. FIG. Also, from each direction of line voltage V32 and phase current I3 for phase 3, the power flow direction of active power W3 and reactive power Var3 is determined. If the direction of power flow is from the power supply terminal to the load terminal, it is determined to be forward power flow, and if it is from the load terminal to the power supply terminal, it is determined to be reverse power flow.

A display unit 2 provided on the front surface of the electronic watt-hour meter 1 is composed of an LCD (liquid crystal display device) 13 . The LCD 13 displays the power flow direction discrimination results of the active powers W1, W3 and the reactive powers Var1, Var3 of each phase by the power flow direction discrimination unit 12 for each phase. The LCD 13 constitutes a load status display unit that displays the load status of load equipment connected to the load terminals of the electronic watt-hour meter 1 . The display control unit 14 causes the LCD 13 to display the active powers W1, W3 and the reactive powers Var1, Var3 of the phases calculated by the power calculation unit 11. The display on the LCD 13 is controlled based on the power flow direction discrimination results for W1, W3 and reactive powers Var1, Var3.

In this embodiment, as shown in FIG. 1, a load state display switch 4 is provided on the upper right side of the front surface of the electronic watt-hour meter 1, along with the weighing pulse setting switches 3a and 3b. These setting changeover switches 3a and 3b and the load state display switch 4 are hidden by a setting section cover (not shown) when they are not operated. The load state display switch 4 is connected to the display control section 14 as shown in the block diagram of FIG. The load state display switch 4 is a display selection switch for selecting display or non-display on the LCD 13 of the power flow direction determination result of the active powers W1, W3 and the reactive powers Var1, Var3 of each phase by the power flow direction determination unit 12. Configure. Based on an operation signal from the load state display switch 4, the display control unit 14 causes the LCD 13 to display or hide the power flow direction determination result according to the operation.

FIG. 4(a) shows how the power flow direction determination result is displayed on the LCD 13 when the electronic watt-hour meter 1 is a three-phase four-wire system and the operation signal from the load state display switch 4 is an ON signal. . The display control unit 14 causes the LCD 13 to display the power flow direction determination result of the active power W and the reactive power Var of each phase by the power flow direction determination unit 12 for each phase. When the power flow direction discrimination result is forward flow, the "+" symbol is highlighted, and when it is reverse power flow, the "-" symbol is highlighted. In this embodiment, this highlighting is done by making the background of the "+" or "-" symbol black. In the figure, the "+" sign is highlighted for the active power W and reactive power Var for all phases Phase 1, Phase 2 and Phase 3. FIG.

FIG. 2(b) shows how the power flow direction determination result is displayed on the LCD 13 when the electronic watt-hour meter 1 is of the three-phase three-wire type and the operation signal from the load state display switch 4 is an ON signal. . In the case of the three-phase three-wire system, the display control unit 14 turns off the display of phase 2. In the case of the single-phase two-wire system, the display of phase 3 is similarly deleted. In the figure, the "+" symbol is highlighted for phase 1 active power W and reactive power Var, while the "+" symbol is highlighted for phase 3 active power W and the phase 3 reactive power Var is highlighted. is highlighted with a "-" sign. Therefore, it can be known from this display mode of the power flow direction that the reactive power Var of phase 3 is reverse power flow.

FIG. 4(c) shows that the electronic watt-hour meter 1 is similarly a three-phase, three-wire system, and phase 3 is unloaded when the operation signal from the load state display switch 4 is an ON signal. The display mode of LCD13 is shown. The display control unit 14 indicates on the LCD 13 the no-load phase 3 for which the active power W and the reactive power Var are not calculated by the power calculation unit 11 by a single symbol "-" as shown.

In addition, the applied voltage identification section 15 is connected to the display control section 14 as shown in the block diagram of FIG. The applied voltage identification unit 15 identifies the magnitude of the voltage applied to the power supply terminal and outputs the identification result to the display control unit 14 . When the voltage identified by the applied voltage identification unit 15 does not fall within a predetermined range of the rated voltage, for example, ±30% of the rated voltage, the display control unit 14 changes the load state display mode of each phase to time. change over time.

For example, when the electronic watt-hour meter 1 is a three-phase three-wire system, the operation signal from the load state display switch 4 is an ON signal, and the voltage identified by the applied voltage identification unit 15 is not within a predetermined range of the rated voltage. Then, as shown in FIG. 5(a), the display control unit 14 changes the load state display mode of each phase to the display mode shown on the left side of the figure and the display mode shown on the right side according to the passage of time. Cyclic display alternately. In the display mode shown on the left side of the figure, the load states of phases 1 and 3 are displayed by symbol pairs of "+" and "-". In the display mode shown to the right, the phase 1 and phase 3 load conditions are indicated by only one of the symbols highlighted "+" or "-", and further indicated by "Phase 1" and "Phase 3". disappears.

Further, when the operation signal from the load state display switch 4 is switched to the OFF signal, the display control unit 14 changes the load state display mode of each phase to the left side of the figure as shown in FIG. The display mode shown and the display mode shown on the right side are alternately cyclically displayed according to the passage of time. In the display mode shown on the left side of the same figure, the active power W and reactive power Var of phases 1 and 3 are indicated by "-" symbols, and in the display mode shown on the right side, the load states of phases 1 and 3 are displayed. All display disappears.

The display control unit 14 is also connected to an open-phase detection unit 16 as shown in the block diagram of FIG. An open-phase detector 16 detects an open-phase in each phase. The display control unit 14 changes the load state display mode only for the phase whose open phase is detected by the open phase detection unit 16 over time.

For example, when the electronic watt-hour meter 1 is a three-phase three-wire system, the operation signal from the load state display switch 4 is an ON signal, and an open phase is detected in the phase 3, the display control unit 14 performs the operation shown in FIG. As shown in (a), the load state display mode of only phase 3 in which an open phase is detected is alternately cyclically displayed on the left side of the same figure and the display mode on the right side according to the passage of time. indicate. In the display mode shown on the left side of the figure, the symbol "-" is displayed for the active power W and reactive power Var of phase 3, and in the display mode shown on the right side, the load state display for phase 3 disappears.

Further, when the operation signal from the load state display switch 4 is switched to the OFF signal, the display control unit 14 changes the load state display mode of the phase 3 to the left side of the figure as shown in FIG. The display mode shown and the display mode shown on the right side are alternately cyclically displayed according to the passage of time. In the display mode shown on the left side of the figure, only phase 3 is displayed with a "-" sign for the active power W and the reactive power Var, and in the display mode shown on the right side, the load state display of phase 3 is completely erased.

According to the electronic watt-hour meter 1 according to the present embodiment, the power flow direction determination unit 12 determines the power flow direction of the active power W and the reactive power Var of each phase, and the power flow direction determination result is used for display control. Each phase is displayed on the LCD 13 by the display control of the unit 14 . This load status display is always displayed regardless of the value of the power factor of the load. Therefore, based on the power flow direction of the active power W and reactive power Var of each phase displayed for each phase, the current load state can be grasped in detail regardless of the value of the power factor of the load. The installer or the like of the meter 1 can always accurately grasp the current situation and quickly deal with the situation.

For example, when the single-phase three-wire electronic watt-hour meter 1 is connected with only pure resistance as a load and the power factor is 1, the vector diagram of voltages V1, V3 and currents I1, I3 is shown in FIG. , voltage V1 and current I1 and voltage V3 and current I3 point in the same direction. In this case, the phase between the respective voltage currents in phases 1 and 3 is 0°, cos0° is a positive value of 1, and sin0° is 0. Therefore, the active powers W1 and W3 of phases 1 and 3, respectively, are positive values, and the reactive powers Var1 and Var3, respectively, are zero. Therefore, the load status indication displayed on the LCD 13 is forward power flow for phase 1 and phase 3 active powers W1 and W3 and no load for reactive powers Var1 and Var3.

Further, when only a capacitor is connected as a load to the single-phase three-wire electronic watt-hour meter 1, the vector diagram of the voltages V1, V3 and the currents I1, I3 is as shown in FIG. I1 and I3 lead voltages V1 and V3 by 90°, respectively. In this case, the phase between the respective voltages and currents in phases 1 and 3 is -90°, cos(-90°) is 0 and sin(-90°) is a negative value of -1. Therefore, the active powers W1 and W3 of phases 1 and 3 are 0, and the reactive powers Var1 and Var3 are negative values, respectively. Therefore, the load status display displayed on the LCD 13 is no load for phase 1 and phase 3 active powers W1 and W3 and reverse power flow for reactive powers Var1 and Var3.

When the three-phase, three-wire electronic watt-hour meter 1 is connected only to a pure resistance as a load and the power factor is 1, the vector diagrams of the line voltages V12, V32 and the phase currents I1, I3 are as follows: As shown in (c), a 60° phase occurs between line voltages V12 and V32, phase current I1 lags line voltage V12 by 30°, and phase current I3 lags line voltage V32 by 30°. ° to move forward. In this case, the phase between the respective voltages and currents in phases 1 and 3 is +30° for phase 1 and -30° for phase 3. cos(+30°), cos(-30°) and sin(+30°) will be positive values and sin(-30°) will be negative values. Therefore, the active powers W1 and W3 and the reactive powers Var1 and Var3 of phases 1 and 3 have positive values, respectively, and the reactive power Var3 has a negative value. Therefore, the load status display displayed on the LCD 13 is such that the active powers W1 and W3 of the phases 1 and 3 and the reactive power Var1 are forward flow, and the reactive power Var3 is reverse power flow.

However, for example, an elevator having a motor as an inductive load and a phase-advancing capacitor is connected as a load device, and the inductive load moves in a state where the phase-advancing capacitor is connected to the electronic watt-hour meter 1 as a load. If not, the vector diagrams of the line voltages V12, V32 and the phase currents I1, I3 are as shown in FIG. That is, the phase current I1 leads the line voltage V12 by 60°, and the phase current I3 leads the line voltage V32 by 120°. In this case, the phase between the voltage and current in phase 1 is -60°, with cos(-60°) being a positive value and sin(-60°) being a negative value. However, the phase between the voltage and current in phase 3 is -120°, and cos(-120°) and sin(-120°) are both negative values. Therefore, the phase 1 active power W1 is positive, but the phase 1 reactive power Var1, the phase 3 active power W3, and the phase 3 reactive power Var3 are negative. Therefore, in the load status display displayed on the LCD 13, the active power W1 of the phase 1 is forward flow, but the reactive power Var1 of the phase 1, the active power W3 and the reactive power Var3 of the phase 3 are reverse power flow.

That is, for phase 3, the phase difference between the voltage V32 and the current I3 exceeds 90°, and the active power W3 is in a reverse power flow state. That is, in the case of a three-phase three-wire system, when the power factor becomes worse than 0.5 (the phase difference is 60°), reverse power flow is detected even if there is no misconnection. At this time, in the conventional electronic watt-hour meter disclosed in Patent Document 2, the power factor falls within the range of 0 to 0.5, and "1" and "3" of each phase reverse current display section are extinguished. Therefore, detailed load status is not known. However, in the electronic watt-hour meter 1 of the present embodiment, unlike the conventional electronic watt-hour meter, the load state display on the LCD 13 is such that the active power W1 for phase 1 is a forward power flow and the reactive power Var1 indicates reverse power flow, and active power W3 and reactive power Var3 for phase 3 both indicate reverse power flow. For this reason, the installer of the electronic watt-hour meter 1 can visually confirm the load state on the LCD 13, so that even if the power factor is extremely low, the capacitor load is currently connected to the electronic watt-hour meter 1. Therefore, it is possible to quickly grasp that there is no erroneous connection in the connection and that no action is required.

Here we describe the case where the load is only a capacitor and the reactive power on the phase 1 side and the reverse power flow on the phase 3 side are detected. A current is detected. Even in this case, the current load state can be known in detail by visually checking the load state displayed on the LCD 13 in the electronic watt-hour meter 1 of the present embodiment. In addition, when reverse power flow is detected without misconnection in this way, if only "reverse power flow" is displayed, misunderstanding may occur. By displaying the load status of each phase in detail, such misunderstandings can be avoided.

Further, for example, when the current line of the phase 1 of the three-phase three-wire electronic watt-hour meter 1 is reversely connected, the phase difference between the voltage V12 and the current I1 for the phase 1 exceeds 90° and the reverse power flow state occurs. becomes. At this time, in the electronic watt-hour meter 1 of the present embodiment, the active power W1 and reactive power Var1 for phase 1 on the LCD 13 are both reverse power flows, the active power W3 for phase 3 is forward power flow, and the reactive power Var3 is reverse power flow. indicates For this reason, the installer of the electronic watt-hour meter 1 recognizes this load state on the LCD 13, and the phase 1 current line is now reversely connected, and it is necessary to reconnect the phase 1 current line. It is possible to quickly grasp that there is a certain state.

Further, according to the electronic watt-hour meter 1 according to the present embodiment, as shown in FIGS. However, by confirming which symbol is highlighted, the power flow direction for each phase can be recognized at a glance. Therefore, it is possible to deal with the matter more quickly.

Further, according to the electronic watt-hour meter 1 according to the present embodiment, as shown in FIG. is informed that Therefore, it is notified that the connection state cannot be determined.

Further, according to the electronic watt-hour meter 1 according to the present embodiment, as shown in FIG. The change over time indicates that the rated voltage of the electronic watt-hour meter 1 is wrong. For this reason, it is urged to change the specifications of the electronic watt-hour meter 1 to one with a rated voltage that matches the voltage of the wiring.

Moreover, according to the electronic watt-hour meter 1 according to the present embodiment, as shown in FIG. be informed that you are For this reason, it is urged to check the wiring connection for the phase displayed as an open phase.

Further, according to the electronic watt-hour meter 1 according to the present embodiment, by operating the load state display switch 4, it is possible to select display or non-display of the power flow direction determination result on the LCD 13. FIG. Therefore, when the load state display on the LCD 13 is not desired, the load state display switch 4 is turned off to hide the load state display, thereby stopping the display of unnecessary information. Gone.

DESCRIPTION OF SYMBOLS 1... Electronic watt-hour meter 2... Display part 4... Load state display switch (display selection switch)
DESCRIPTION OF SYMBOLS 11... Electric power calculating part 12... Power flow direction discrimination|determination part 13... LCD (liquid crystal display device; load state display part)
14 Display control unit

Claims (2)

A power calculation unit that calculates the active power and reactive power of each phase, a power flow direction determination unit that determines whether the power flow direction of the active power and reactive power of each phase is forward flow or reverse power flow, and each The power flow direction determination results for the active power and reactive power of the phase are obtained for each phase of phase 1, phase 2, and phase 3. By arranging vertically aligned pairs of "+" and "-" symbols for each phase horizontally, and by aligning each of the "+" symbols and each of the "-" symbols in each phase in a row, the tidal current When the direction determination result is forward power flow, each "+" symbol is highlighted, and when it is reverse power flow, each "-" symbol is highlighted, regardless of the value of the power factor of the load. Based on the power flow direction determination result of the active power and reactive power of each phase by the load state display unit that always displays as a combination of the determination results of forward power flow or reverse power flow arranged for each phase, and the power flow direction determination unit A three-phase four-wire electronic watt-hour meter, comprising: a display control section for controlling display of the load state display section. A power calculation unit that calculates the active power and reactive power of each phase, a power flow direction determination unit that determines whether the power flow direction of the active power and reactive power of each phase is forward flow or reverse power flow, and each The power flow direction determination results for phase active power and reactive power are shown for each phase of phase 1 and phase 3, and the symbol pair of "+" and "-" arranged vertically for active power and the symbol pair for reactive power Sets of pairs of "+" and "-" symbols arranged vertically are arranged horizontally, and each "+" symbol and each "-" symbol in each phase are arranged horizontally in a row to determine the power flow direction. With each "+" sign highlighted if the result is forward flow and each "-" sign if reverse flow, regardless of the value of the load power factor, always: A load state display unit that displays a combination of the determination results of forward power flow or reverse power flow arranged for each phase; A three-phase three-wire electronic watt-hour meter, comprising: a display control section for controlling display of a state display section.

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