JP2000162252A - Watthour meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a watthour meter which can easily measure changes in power consumption. SOLUTION: The voltage value of an a.c. distribution line is detected by a voltage input part 11, and a current value of the a.c. distribution line is detected by a current input part 12. The detected voltage value and current value are multiplied by an operating means 20, whereby the amount of electrical energy passing the a.c. distribution line is obtained. The obtained amount of electrical energy is displayed by a liquid crystal display device 31. The operating means 20 has a clock part 23. The clock part 23 measures in units of weeks, days and hours, so that the amount of electrical energy for every unit can be displayed at the liquid crystal display device 31.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a watt hour meter which is attached to a power supply path to a load on a wiring path and displays and displays the amount of power supplied to the load.

[0002]

2. Description of the Related Art As a watt-hour meter of this type, recently, a watt-hour meter which obtains a power amount by multiplying a voltage value and a current value of a wiring path and integrating over time (that is, integration) has been provided. This type of watt hour meter can generally display the amount of power that has elapsed since the start of measurement.
That is, at present, only the accumulated value of the electric energy (integrated power) can be displayed.

[0003]

However, in recent years, it has been proposed to promote energy saving, and for this purpose, it is necessary to analyze the transition of the power consumption of each customer or each facility. Deemed necessary.

[0004] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a watt hour meter capable of easily measuring a change in power consumption.

[0005]

According to a first aspect of the present invention, there is provided a voltage input section for detecting a voltage value of a wiring path, a current input section for detecting a current value of a wiring path, and a method for detecting the detected voltage value and current value. Calculating means for calculating the amount of power passed through the wiring path using the display means, and display means for displaying the amount of power obtained by the calculating means, wherein the calculating means displays the elapsed time and the unit date and time from the start of measuring the amount of power. A clock section for measuring time, and an arithmetic circuit for respectively obtaining an electric energy from the start of measurement and an electric energy for each unit date and time, wherein the display means displays the electric energy from the start of measurement and the electric energy for each unit date and time. It is. here,
The unit date and time is an hour unit in the embodiment described below,
It means one day or one week. That is, it is possible to display the amount of power for each hour, the amount of power for each day, and the amount of power for each week. Thus, not only can the power amount from the start of measurement be displayed, but also the power amount for each unit date and time can be displayed, so that it is easy to know the transition of the power consumption.

According to a second aspect of the present invention, in the first aspect of the present invention, an operation means for instructing the display means to selectively display the electric energy from the start of the measurement and the electric energy for each unit date and time is added. The amount of power from the start of the measurement and the amount of power for each unit date and time are selectively displayed on the display means, so that the information can be displayed at once on the display means, but various information can be displayed even if the amount of information is small. Yes, resulting in miniaturization. In addition, if the amount of power from the start of measurement is always displayed on the display means, information that does not need to be displayed at all times, such as the amount of power per unit day, is not displayed, which is convenient.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the calculating means has a function of obtaining an instantaneous power, and comprises a storage unit for storing a peak value of the instantaneous power. By storing the peak value of the instantaneous power, the maximum power required by the customer or facility can be known.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the clock unit has a function of measuring the current date and time, and the storage unit stores the instantaneous power peak value and the date and time when the peak value occurred. Since it is possible to know the peak value of the instantaneous power and the date and time when the peak value occurred, power transmission according to the power demand becomes possible.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description, as shown in FIG.
An AC wiring path L including three lines L1 to L3 connecting an AC power supply AC and a load LD, such as a single-phase three-wire system or a three-phase three-wire system, is assumed to be a wiring path. In the present embodiment, three probes P1 to P3 that are connected to the lines L1 to L3 of the AC wiring path L and detect line voltage, and two lines L1 and L3 of the AC wiring path L are It has two current sensors CT1 and CT2 penetrated. Current sensor C
T1 and CT2 are provided with openable and closable annular cores. After the annular core is opened and the lines L1 and L3 of the AC wiring path L are introduced and the annular core is closed, the lines L1 and L1 of the AC wiring path L are inserted into the annular core. A clamp sensor that restricts L3 to penetrate and a current transformer that is generally used are used.

As shown in FIG. 1, the probes P1 to P3 constitute a part of the voltage input section 11, and the current sensors CT1 and C3
T2 constitutes a part of the current input unit 12. Voltage input 1
1 and a current input unit 12, a filter for removing a frequency component unnecessary for detecting power supplied from the AC power supply AC to the load LD through the AC wiring path L, and a gain set according to the input value. And a current-current conversion circuit are provided as appropriate. The voltage value and the current value detected by the voltage input unit 11 and the current input unit 12, respectively, are converted into a pre-processing circuit 13
And the polarities and absolute values of the voltage value and the current value are obtained. That is, the preprocessing circuit 13 detects the
Are provided with polarity detection circuits 14a and 14b for respectively detecting the polarities of the voltages of the other probes P1 and P3 when the voltage applied to is set to the reference potential (0 V), and rectifier circuits 15a and 14b for full-wave rectification of both voltages. 15b. Also,
The preprocessing circuit 13 includes polarity detection circuits 16a and 16b for detecting the polarities of the currents detected by the two current sensors CT1 and CT2, respectively, and includes rectification circuits 17a and 17b for full-wave rectification of both currents.

Each of the polarity detection circuits 14a, 14b, 16a,
16b is configured to detect a zero-cross point of a voltage waveform or a current waveform, and generate a binary signal corresponding to the polarity between adjacent zero-cross points. Therefore, the probes P1 to P3 or the current sensors CT1,
If the AC voltage or AC current detected by CT2 is, for example, a sine wave as shown in FIG. 3 (a), the output of each polarity detection circuit 14a, 14b, 16a, 16b is shown in FIG.
A rectangular wave signal as shown in FIG. In addition, the rectifier circuit 15
The outputs of a, 15b, 17a, and 17b have a pulsating waveform as shown in FIG.

The polarity detection circuits 14a, 14b, 16a, 1
The polarity of the AC voltage or the AC current detected by 6b and the absolute value of the AC voltage or the AC current detected by the rectifier circuits 15a, 15b, 17a, and 17b are each provided with an arithmetic circuit 21 mainly composed of a microcomputer. Is input to the calculating means 20. The arithmetic circuit 21 includes the rectifier circuits 15
A, 15b, 17a, and 17b have the function of A / D converting the output, and the digital value after A / D conversion has a code corresponding to the polarity detected by the polarity detection circuits 14a, 14b, 16a, 16b. Will be added.

Here, since the object to be subjected to A / D conversion is a pulsating waveform, the AC waveform (see FIG. 3 (a)) is converted into an A / D converter without changing the dynamic range of the A / D converter.
As compared with the case where the / D conversion is performed, the step width per bit can be reduced, and as a result, the resolution is increased. The thus obtained instantaneous values of the AC voltage and the AC current are multiplied by a signed digital value corresponding to the instantaneous value. Here, the sampling cycle at the time of A / D conversion is set appropriately (to a cycle sufficiently shorter than the cycle of the AC power supply AC), and after the sum of the multiplied values for one cycle of the AC power supply AC is obtained, This value corresponds to the instantaneous power (effective value) when divided by the number of samplings. In addition, for the power amount in the desired period, the sum of the instantaneous power in the period is obtained.
This calculation is equivalent to integrating the power over time.

FIG. 4 shows a procedure for calculating the power in the arithmetic circuit 21. That is, the outputs of the rectifier circuits 15a and 15b corresponding to the absolute value of the AC voltage are converted to A / D
After the conversion (S1), the code detected by the polarity detection circuits 14a and 14b is input (S2), and a code is added to the digital value obtained by the A / D conversion (S3). Also,
After the A / D conversion of the outputs of the rectifier circuits 17a and 17b corresponding to the absolute value of the alternating current (S4), the polarity detection circuit 16
a, the code detected by 16b is input (S5), and A
A sign is added to the digital value obtained by the / D conversion (S6). When the values V1 and I1 corresponding to the voltage value and the current value of the AC power supply are obtained in steps S3 and S6 in this manner, the arithmetic means 10 calculates these values V1 and I1.
Is obtained as the instantaneous value W1 (= V1 × I1) (S7). The obtained instantaneous values W1 are sequentially added (S8),
Instantaneous value W1 for one cycle of the voltage waveform of AC power supply AC
Is obtained (S9), and the added value W0 is divided by the number N of samples (S10). The division value thus obtained corresponds to the instantaneous power.

The electric energy is often obtained within a fixed period, such as weekly, daily, or hourly. These periods are measured by a clock unit 23 provided in the arithmetic means 20. That is, when the operation is started, a signal indicating a break of week, day, and time is input to the arithmetic circuit 21 by the clock unit 23, and when this signal is input to the arithmetic circuit 21, the electric energy in the corresponding period is reduced. Unnecessary data that has been written into the storage unit 22 composed of an EEPROM and that has become old is deleted from the storage unit 22. The storage unit 22 also stores the peak value of the instantaneous power and the date and time when the peak value occurred. The clock unit 23 also has a function of measuring the elapsed time from the start of the measurement of the electric energy. A display operation unit 30 having a liquid crystal display 31 and a keypad 32 as display means is connected to the arithmetic means 20. The function of the display operation unit 30 will be described later.

By the way, the preprocessing circuit 13 and the arithmetic means 2
0, the internal power supply of the display operation unit 30 and the like is a probe P1,
It is supplied from the AC wiring path L through P2. That is,
A power supply circuit 40 is connected to the probes P1 and P2, and a constant DC voltage is output from the power supply circuit 40 and used as an internal power supply. This power supply circuit 40 is, as shown in FIG.
Is connected to the voltage input unit 11 via a power switch SW (not shown), and the AC voltage input through the high-frequency blocking filter circuit F is subjected to full-wave rectification by a rectifier DB composed of a diode bridge, and thereafter, by a smoothing capacitor C1. Smooth. A series circuit of a switching element Q1 composed of a MOSFET and a resistor R1 for current detection is connected between both ends of the smoothing capacitor C1 via a primary winding of a transformer T1. Therefore, if the switching element Q1 is turned on / off at a high frequency, an AC output can be obtained on the secondary side of the transformer T1, and a DC voltage is generated by rectifying the AC output on the secondary side. . This type of circuit configuration is known as a DC-DC converter.

The secondary output of the transformer T1 is taken out of three secondary windings, and one secondary winding is provided with a center tap. That is, in the pre-processing circuit 13, the polarity detection circuits 13a, 13b, 15a, and 15b are provided, and this type of circuit is generally configured using an operational amplifier. Since a positive / negative bipolar power supply (for example, ± 12 V) is required, the secondary winding of the portion for supplying power to the preprocessing circuit 13 is provided with a center tap so that a positive / negative bipolar power supply can be easily configured.
The power supply to the arithmetic means 20 and the display / operation unit 30 is set to, for example, 5V. Preprocessing circuit 13, arithmetic means 20,
Since the display operation unit 30 requires a constant DC voltage,
Rectifier diodes D2 to D2 are provided on the secondary side of the transformer T1.
4 and a smoothing capacitor C2 to C4 as well as a constant voltage circuit 41a as a constant voltage means for making the voltage across the capacitors C2 to C4 constant.
To 41c to stabilize the supply voltage.

The remaining secondary winding provided in the transformer T1 is
The control circuit CN is provided to supply power to a control circuit CN for turning on and off the switching element Q1, and the control circuit CN is provided with a control power supply circuit 42 to which power is supplied from the transformer T1. However, since power cannot be supplied to the control power supply circuit 42 through the transformer T1 before the on / off of the switching element Q1 is started, power can be supplied to the control power supply circuit 42 from the smoothing capacitor C1 through the resistor R2 at startup. It is. The control circuit CN basically includes an oscillating circuit 43 for generating a pulse signal for determining the ON / OFF timing of the switching element Q1, and a switching element Q based on the output of the oscillating circuit 43.
A feedback circuit 45 for keeping the input voltage to the constant voltage circuit 41c substantially constant, and a current flowing through the switching element Q1 to both ends of the resistor R1. The control circuit CN is provided with a current limiter circuit 46 which monitors by voltage and limits the current flowing through the switching element Q1. The output of the voltage detection circuit 47 for monitoring the input voltage of the constant voltage circuit 41c is supplied to the feedback circuit 45 by a photocoupler PC.
Has been entered through. That is, the switching element Q is controlled so that the input voltage to the constant voltage circuit 41c is kept substantially constant.
The on / off timing of 1 is feedback-controlled.

As described above, since the power is supplied to the power supply circuit 40 for generating the internal power from the AC wiring line L through the probes P1 and P2, it is possible to use a battery as the internal power or to obtain the internal power. It is not necessary to separately provide an adapter, and the connection work to the AC wiring path L is facilitated. Moreover, in order to stabilize the secondary output of the transformer T1, a circuit configuration for feedback-controlling the ON / OFF timing of the switching element Q1 is employed, and furthermore, since the constant voltage circuits 41a to 41c are provided, the voltage of the AC power supply AC is reduced. Constant voltage circuits 41a to 41
The output voltage of c is maintained at a constant voltage, so that even if the specifications of the AC power supply AC are different, it is possible to cope with the same configuration.

Incidentally, the AC power supply AC may cause a power failure, and if the power supply to the clock unit 23 is stopped when the power failure occurs, it is necessary to reset the time of the clock unit 23 when the power is restored, which is troublesome. It is something that takes. Therefore, a backup power supply circuit 48 is provided so that power can be supplied to the clock unit 23 even when the power supply from the power supply circuit 40 to the arithmetic unit 20 is stopped. The backup power supply circuit 48 uses a secondary battery, and this secondary battery is charged by the output voltage of the power supply circuit 40 during normal operation, and supplies power to the clock unit 23 during a power failure. Therefore, even during a power failure, the clock unit 23 operates normally, and it is not necessary to set the time when the power is restored. In addition, since the secondary battery is a secondary battery, it does not need to be replaced for a long time. Further, since the secondary battery is normally charged, it is not necessary to separately charge the secondary battery.

By the way, the keypad 3 of the display operation unit 30
2 is a start / stop key K as shown in FIG.
The keypad 32 includes five operation units: a mode switching key K2, selection keys K3, K4, and a reset key K5.
Is used in combination with the liquid crystal display 31,
It is possible to set the time, set the measurement period of the electric energy, selectively display the electric energy to be displayed among the electric energy in various measurement periods, and the like. The selective display of the electric energy means that the electric energy is selected and displayed, for example, weekly, daily, or hourly.

This will be described more specifically. In the present embodiment, it is assumed that data for analyzing a daily change, a weekly change, a monthly or yearly change of the electric energy is obtained, and the electric power for each period such as week, day, and time is obtained. Since it has a function of measuring the amount, the power is turned on as shown in FIG.
1) Immediately after that, time adjustment is required (S2, S3).
As shown in FIG. 8, the time adjustment is performed by pressing the mode switching key K2 for one second or more immediately after the power is turned on to select the time adjustment mode. The measurement of the electric energy is not performed while the time adjustment mode is selected. When the time setting mode is selected, the date is displayed as shown in FIG. 8A, and the numerical value corresponding to the year blinks (the blinking is indicated by surrounding it with a square). Thereafter, the mode switching key K
Each time the operation 2 is performed, the numerical value corresponding to the month blinks as shown in FIG. 8B, the numerical value corresponding to the day blinks as shown in FIG. 8C, and as shown in FIG. 8D. The state in which the hour and minute are displayed and the numerical value corresponding to the hour blinks, and the state in which the numerical value corresponding to the minute blinks as shown in FIG.
When the mode switching key K2 is pressed in the state of (e) (that is, when the mode switching key K2 is pressed five times in the time setting mode), the time setting mode ends (S3).
By operating the selection keys K3 and K4 when the numerical value is blinking in each state of FIGS. 8A to 8E, the blinking numerical value can be increased or decreased. You can match the minutes. Further, if the mode switching key K2 is kept pressed for one second or more in the time setting mode, the time setting mode is canceled.

After the completion of the time adjustment, a selection is made as to whether the AC wiring path L is single-phase or three-phase. That is, the phase setting mode is selected by the mode switching key K2,
The operation of K4 selects single phase or three phase. The liquid crystal display 31 displays 1 for single-phase and 3 for three-phase. Thereafter, the timer setting mode is selected by the mode switching key K2, and an operation for designating the start time and the end time of the measurement of the electric energy is performed.

The timer setting mode includes an on mode and an off mode. In the on mode, an on time (year, month, day, hour, minute) is set. In the off mode, an off time (year, month, day, hour, minute) is set.
Can be set. The timer setting mode can be selected with the mode switching key K2, and the ON mode and the OFF mode are selected by the selection keys K3 and K4. The operations in the ON mode and the OFF mode of the timer setting mode are operations for designating the year, month, day, hour, and minute, respectively, and are the same operations as those in the time setting mode, as shown in FIGS. In short, after selecting which numerical value for year, month, day and time is to be set with the mode switching key K2, the numerical value is changed using the select keys K3, K4 in a state where the numerical value is selected. Here, in the ON mode or the OFF mode of the timer setting mode, if the reset key K5 is operated, 1
The previous item (year, month, day, hour, minute) can be returned to the selected state. When the mode switching key K2 is pressed for one second or longer, the screen returns to the initial screen of the timer setting mode, that is, the screen for selecting the ON mode and the OFF mode. put it here,
In the ON mode, the timer setting mode does not end with the fifth pressing operation of the mode switching key K2, but shifts to the OFF mode. In the off mode, the timer setting mode ends with the fifth operation of the mode switching key K2. After the setting of the start time and the end time of the measurement of the electric energy is completed by the above operation (S4 to S6), the clock unit 2
When the current time measured in Step 3 reaches the set start time (S7), the measurement of the electric energy is started (S9). Even when the start time and the end time of the measurement of the electric energy are not set, when the start of the electric energy measurement is instructed by the start / stop key K1 (S8), the measurement of the electric energy is started (S9). ). The start / stop key K1 is used to start and end the measurement for each pressing operation.

In the measurement of the electric energy, as shown in FIG. 4, the voltage value and the current value of the AC wiring line L are obtained (S10, S10).
11) An instantaneous power is obtained based on the voltage value and the current value (S12). Further, the integrated value of the obtained instantaneous power is set as the power amount (S13), and the power amount is written in the storage unit 22 in units of one hour, one day, and one week (S14 to S2).
4). Specifically, one hour after the start of measurement (S
14) The electric energy within one hour is obtained (S15), and the timer for limiting the one hour is reset (S16). The same processing is performed when one day has passed (S17) and one week has passed (S20). In this way, the power amount obtained at each time point when the power amount for each hour, day, and week is obtained is displayed on the liquid crystal display 31 (S23), and the power amount is stored in the storage unit 22. (S24).

When the set measurement end time has elapsed (S25), the power measurement ends (S26), and even if the measurement end time has not elapsed, the end of measurement is instructed by the start / stop key K1. (S27), the power measurement ends.

By the way, during the measurement of the electric energy, a display mode having different contents to be displayed on the liquid crystal display 31 can be selected by pressing the mode switching key K2. The display mode includes a current value display mode for displaying the value being measured, a peak power display mode for displaying the peak value of instantaneous power, an integrated power display mode for displaying the amount of power (integrated power) from the start of measurement, and each time. Hourly display mode in which the amount of power can be displayed up to 167 hours, daily display mode in which the amount of power can be displayed up to seven days ago, and week in which the amount of power can be displayed up to four weeks ago Each display mode can be selected.

In the present value display mode, the selection keys K3, K
4, the instantaneous electric power as shown in FIG.
The display content can be selected from three types, that is, a voltage (see FIG. 3B) and a current (see FIG. 3C). Also, when any value is displayed, the mode switching key K2
The display can be shifted to another display mode by pressing the button. The current value display mode displays each value of voltage, current, and instantaneous power together with the current time and minute.

In the peak power display mode, the peak value of the instantaneous power is displayed.
2 (a)) and hour and minute (see FIG. 12 (b)) can be selected with the selection keys K3 and K4. The date or hour and minute and the peak value are displayed on the screen of the liquid crystal display 31 in two stages. As is clear from the operation in the time setting mode or the like, the liquid crystal display 31 in the present embodiment has a relatively small screen, and it is necessary to display the date and time separately from the screen. Therefore, the display of the date is switched between the display of the date and the display of the hour and minute. Further, when the reset key K5 is operated in the peak power display mode, the peak value of the instantaneous power after the reset key K5 is pressed is obtained, and when the peak power display mode is next selected, the peak power display mode is set before. The peak value from the point when the reset key K5 is selected and operated is displayed. This display mode ends when the mode switching key K2 is pressed.

In the integrated power display mode, the elapsed time from the start of the measurement and the integrated power are displayed on the screen of the liquid crystal display 3 in two stages as shown in FIG. Further, by operating the selection keys K3 and K4 in this mode, the date when the measurement is started (see (b) in the same figure),
It is possible to select and display the hour and minute (see FIG. 3C). Furthermore, when this mode is selected after the end of the measurement, in addition to the elapsed time, the start date, the start time, and the end date (see FIG. 3D), the end time (see FIG. ) Can be displayed. This display mode ends when the mode switching key K2 is pressed.

The hourly display mode, the daily display mode, and the weekly display mode are basically similar modes.
4), a day (see FIG. 15), and a weekly (see FIG. 16) data are read and displayed on the liquid crystal display 31. However, the period during which display can be performed retroactively is limited as described above due to the storage capacity and practical necessity. In each display mode, the display period can be selected by operating the selection keys K3 and K4. For example, it is possible to select how many hours before the current hour the power amount is displayed. Further, in the hourly display mode and the daily display mode, how many hours ago (how many days ago) the display is made by pressing the reset key K5 (see FIGS. 14 (a) and 15 (a)), hour, minute and year Whether the date and time are specified (FIG. 14 (b), FIG. 15 (b)
Reference) can be selected. In these display modes, if the start / stop key K1 is pressed,
The contents of the storage unit 22 can be deleted. These display modes are terminated by pressing the mode switching key K2.

[0032]

According to the first aspect of the present invention, there is provided a voltage input section for detecting a voltage value of a wiring path, a current input section for detecting a current value of the wiring path, and a wiring path using the detected voltage value and current value. Computing means for calculating the amount of power passed through, and display means for displaying the amount of power determined by the computing means, the computing means,
A clock unit for measuring the elapsed time from the start of the measurement of the electric energy and for each unit date and time; and an arithmetic circuit for respectively obtaining the electric energy and the electric energy for each unit date and time from the start of the measurement. It displays the amount of electricity and the amount of power for each unit date and time. This has the effect of making it easier to know

According to a second aspect of the present invention, in the first aspect of the present invention, an operation means for instructing the display means to selectively display the electric energy from the start of the measurement and the electric energy for each unit date and time is added. Since the amount of power from the start of measurement and the amount of power for each unit date and time are selectively displayed on the display means, it is possible to display the information at once on the display means, but it is possible to display various information even if the amount of information is small. There is an advantage that it leads to miniaturization as a result. In addition, if the amount of power from the start of measurement is always displayed on the display means, there is an advantage that information that does not need to be displayed at all times, such as the amount of power per unit day, is not displayed and the usability is good.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the calculating means has a function of obtaining instantaneous power, and comprises a storage unit for storing a peak value of the instantaneous power. By storing the peak value of the power, there is an effect that the maximum power required by the customer or the facility can be known.

According to a fourth aspect of the present invention, in the third aspect, the clock section has a function of measuring the current date and time, and the storage section stores the instantaneous power peak value and the date and time when the peak value occurred. Because it is possible to know the date and time when the peak value occurred along with the peak value of the instantaneous power,
There is an effect that power transmission according to power demand becomes possible.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a schematic view showing a usage pattern of the above.

FIG. 3 is an operation explanatory view of the above.

FIG. 4 is an operation explanatory diagram of the above.

FIG. 5 is a circuit diagram showing a power supply circuit used in the power supply circuit;

FIG. 6 is a front view showing the keypad in the above.

FIG. 7 is an operation explanatory diagram of the above.

FIG. 8 is an operation explanatory view of the above.

FIG. 9 is an operation explanatory view of the above.

FIG. 10 is an operation explanatory view of the above.

FIG. 11 is an operation explanatory diagram of the above.

FIG. 12 is an operation explanatory view of the above.

FIG. 13 is an explanatory diagram of the operation of the above.

FIG. 14 is an operation explanatory view of the above.

FIG. 15 is an explanatory diagram of the operation of the above.

FIG. 16 is an operation explanatory view of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Voltage input part 12 Current input part 20 Arithmetic means 21 Arithmetic circuit 22 Storage part 23 Clock part 30 Display operation part 31 Liquid crystal display 32 Keypad L AC wiring path

Claims (4)

[Claims] 1. A voltage input section for detecting a voltage value of a wiring path, a current input section for detecting a current value of the wiring path, and calculating an amount of power passing through the wiring path using the detected voltage value and current value. Computing means, and display means for displaying the amount of power obtained by the computing means, the computing means comprising: a clock section for measuring the time elapsed from the start of the measurement of the electric energy and the unit date and time; and the electric power from the start of the measurement. A watt hour meter, comprising: an arithmetic circuit for calculating the amount and the amount of power for each unit date and time, wherein the display unit displays the amount of power from the start of the measurement and the amount of power for each unit date and time. 2. The electric energy according to claim 1, further comprising operation means for instructing the display means to selectively display the electric energy from the start of the measurement and the electric energy for each unit date and time. Total. 3. The watt hour meter according to claim 1, wherein said calculating means has a function of obtaining instantaneous power, and comprises a storage unit for storing a peak value of instantaneous power. 4. The clock unit according to claim 3, wherein the clock unit has a function of measuring a current date and time, and the storage unit stores a peak value of instantaneous power and a date and time when the peak value occurs. Watt hour meter.