JPH0269676A - Watt-hour meter - Google Patents

Abstract

PURPOSE:To make a watt-hour meter capable of coping with a power rate change by inputting a using unit price from a unit price setting means and displaying a consumed power rate in a digital value. CONSTITUTION:An electric current is made to flow to a current transformer in accordance with a load and an electric energy calculating means calculates consumed electric energy based on current signals and set data of a voltage, etc., through a signal conversion circuit. Then an integrated electric energy calculating means calculates the integrated electric energy. On the other hand, a consumed power rate calculating means calculates the consumed power rate by a using power rate unit price set by a unit price setting means. The integrated electric energy and consumed power rate are displayed in a displaying means in digital values. Therefore, a change in power rate can be coped with when the unit price is reset by means of the unit price setting means.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Field of Industrial Application The present invention relates to an integrating wattmeter, and particularly to an integrating wattmeter that numerically displays the power consumption rate.

(B) Conventional Technology In general, a moving magnetic field type inductive integrating wattmeter is used to measure the amount of power at commercial frequencies used in businesses and homes. In this type of integrated wattmeter, the amount of power used is displayed by a mechanical needle indicating the number of rotations of an aluminum disc that is obtained according to the amount of power used, or by a mechanical digital display. Ta.

(c) Problems to be Solved by the Invention The above-mentioned conventional integrating wattmeter is a fixed type, and there is a problem in that it is difficult to set it freely, and usage charges cannot be read directly. In order to solve this problem, a current transformer that is connected to the power line to be measured and detects the current, a signal conversion circuit that amplifies the current signal detected by the current transformer and converts it into a DC signal, Based on the current signal from this signal conversion circuit, a power amount calculation means calculates power, an integrated power amount calculation means integrates the calculated power amount, and a predetermined operation is performed on this integrated power amount to calculate the integrated power amount. We have created a product W wattmeter consisting of a usage fee calculation means for calculating the usage fee and a display means for digitally displaying the integrated power amount and usage fee, and have already filed a separate application.

However, if the usage fee calculation means stores a usage fee table for the integrated power amount or a usage fee unit price fixedly in a ROM, etc., there is a problem that it cannot respond when the usage fee is revised. was there.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an integrating power meter that can respond to rate revisions.

(d) Means and Effects for Solving the Problems The integrating wattmeter of the present invention includes a current transformer that is coupled to a power line to be measured and detects current, and amplifies the current signal detected by the current transformer. and a signal conversion circuit that converts it into a DC signal, a power amount calculation means that calculates power based on the current signal from this signal conversion circuit, an integrated power amount calculation means that integrates the calculated power amount, and a power amount calculation means that calculates the amount of power used. a unit price setting means for inputting and setting a unit price;
It is comprised of a usage fee calculation means that calculates the usage fee by multiplying the calculated integrated power amount by the input and set unit price, and a display means that digitally displays the integrated power amount and usage fee ( (See Figure 1).

In this integrated wattmeter, when a current transformer is connected to the power line to be measured, a current flows through the current transformer in accordance with the load power, and this current signal is amplified and converted to direct current in a signal conversion circuit, resulting in the amount of power The calculation means multiplies the current signal by setting data such as a set voltage, and calculates the electric energy. Then, as time passes, this power amount is integrated by the integrated power amount calculation means, and the integrated power amount for a predetermined period is calculated. On the other hand, since the unit price of the usage fee is input and set by the unit price setting means, the usage fee calculation means multiplies the integrated power amount and the unit price to calculate the usage fee. Then, the calculated integrated power amount and usage fee are digitally displayed on the display means. If you want to change the unit price, enter it again using the unit price setting method.

(E) Examples The present invention will be explained in more detail with reference to Examples below.

FIG. 2 is a circuit diagram of an integrating power meter showing an embodiment of the present invention. This integrating power meter includes a CPUI, a clock oscillator 2 for generating a synchronization signal, and terminals P+-Pz-(P+b
, Pzb) is externally connected to the current transformer CT+ (CT
z) (see Figure 3), a signal conversion circuit 3a (3b) that converts the current detected by the current transformers CT and (CT2) into a signal and inputs it to the CPUI, and a display that displays a 4-digit numerical value. (
LED) 4 and a finger drive circuit 6 that drives the display 4.
, the segment decoder 7 and the terminals P3 and Pa receive a commercial voltage of 100 cm, and each circuit receives +12V and -12V.

A power supply circuit 7 that supplies a power supply voltage such as +5V, a power supply voltage drop detection circuit 8 that detects a drop in power supply voltage, and a CPUI.
It consists of a backup circuit 9 for backing up the internal memory (RAM), indicator lights L+, Lz, . . . L4, and various setting switches SW1, SW2, .

The signal conversion circuit 3a is an operational amplifier AM, AM.

It includes an absolute value rectifier circuit consisting of terminals Pi, Pea
It has the functions of amplifying, full-wave rectifying, and smoothing the signal corresponding to the detected current input through the sensor.

Furthermore, a smoothing circuit that further smoothes the rectified and smoothed current signal and includes a delay function to suppress sudden changes is provided at the subsequent stage of the operational amplifier AM2. The signal conversion circuit 3a converts a current corresponding to the current flowing through the system under test detected by the current transformer CT into a DC component and inputs it to the CPUI. In this integrated power meter, in addition to the current transformer CTC1 signal conversion circuit 3a, a current transformer CT2 and a signal conversion circuit 3b are arranged in parallel so that the electric energy of two systems can be measured. The signal conversion circuit 3b is a circuit having the same configuration and function as the signal conversion circuit 3a.

Switches SW1, SW2, ..., SWl. dip switches are used in both, among which switches SW,
, S W z and S W x are setting switches related to the current transformer CT, and are set to 100 V/200 of the load power supply voltage.
V, single phase/three phase, and current transformer rating 2OA/1
It is not possible to set a different value for 00A. Similarly, switches SW4, SW3, SW are setting switches for current transformer CT2, each with 10 n V/200
This is for setting V, single phase/three phase, and 20A/100A. Switches SW1, SW6, SW9 are I
This is to add and set the unit price per KWh. Regarding the unit price, the standard unit price of 18 yen is registered and stored in the CPUI in advance, and the yen to be added to this is set using switches sw, , 5Wll, and SWq. Set.

Set +1 yen, +2 yen, and +4 yen, respectively. Therefore, in this example integrated wattmeter, a unit price of 18 yen to 25 yen can be set. For example, if 20 yen is to be set as the unit price, switch SW8 may be turned on. As a result, +2 yen and the basic fee of 18 yen will be added,
20 yen is stored as the unit price. Switch SW...
This is for setting the two-phase detection mode in three phases.

The switch SW + + is for resetting, and the switch SW, 2 is a switch for changing the display.

Switches SW1, SW2, ..., SWlg 0N10
The FF state is taken into the CPU 1.

The CPUI has an A/D conversion function, a function of converting the current signal ■ into a digital signal from the two signal conversion circuits 3a and 3b, and taking in the digital signal, and switches SWI, . . . , S
W3, SW4, . . . It has a function of reading reference data determined by the setting conditions of SW6 from the built-in ROM and multiplying it by the current signal I to calculate the amount of electric power. Here, the reference data is the amount of power output when a current signal equivalent to 1 bit is input from the A/D converter, and the reference data is 100V/200V, single phase/three phase, 20A/
Eight types of 100A are stored. For example, if the A/D converter is 256 bits, the current transformer CT
, if the settings are 200■, three-phase, and 2OA, then the reference data D has a power factor fixed at 0.85.

The CPU also has a function that calculates the cumulative power amount by integrating the power amount, a function that calculates the usage fee by multiplying the calculated cumulative power amount by the set unit price, and a function that calculates the usage fee by turning on switch 5WI2.
10 FF It has a function of switching and outputting the integrated power amount and usage fee to the display 4 according to the FF setting status.

The indicator light L+ lights up when the display is switched to fare. This indicator light has a weight of 100 yen. Therefore, if the indicator light is lit and the display on the display 4 is 52, the estimated usage fee is 5,200 yen. The indicator light L2 lights up when the display is switched to the integrated power amount. indicator light,
, L, respectively, the specifications of current transformers CT, , Cr2 are 10
It is an OA and lights up when the switches SW3 and SW are turned on.

FIG. 4 is an external plan view of the integrated power meter of the above embodiment.

In the figure, a display 4,
Indicator light Ll % LX, reset button SW, display switching button SW, 2. is placed so that it can be seen visually,
The other circuit sections shown in FIG. 2 are housed within the main body case 20. Most button SW,,,,SW1□
1 is covered by a transparent cover 20a of the main body case 20, and the reset button SW++- is covered by the main body case 20.
If you do not remove a, you will not be able to operate the display switch button 5W.
12° cannot be set to 0N10FF unless a rod or the like is inserted through the small hole 20b, thereby preventing erroneous settings caused by easy touching with hands or the like.

When using this embodiment of the integrated power meter, the terminal P Ill
, P, and the current transformer CT connected to P, and the terminal P0, Pub
The current transformers CT2 connected to the current transformers CT2 are respectively inserted and connected to a tree of the load power lines to be measured. Then, the settings for each current transformer CT, CT2 are set using the switch SW.
, . . . is performed with SW6. In this case, the current transformer CT +
The settings for the current transformer CT and the current transformer CT are made individually, and if the power systems are different, the settings for both current transformers may be different.

Therefore, for current transformer CT r , switch SW1
is set to 100V, whereas the setting of switch SW4 by current transformer CT2 can be set to 200V. Also, while the setting by switch SW2 is two-phase, the setting by switch SW5 can be set to 200V. There is no problem even if it is single-phase. However, the two-way flow device CT, ,C
This is a case where R2 is connected to one of the same three-phase load power lines, and a current signal corresponding to the amount of power is detected by each series, and the amount of power obtained based on this is averaged. SW. In the case of two-phase detection in three phases when is ON, current transformers CT, ,
It is necessary that Cr2 have the same condition settings.

Further, an additional charge for 18 yen is set using switches SW, . . . , SW. 18 whose unit price corresponds to the standard charge
In the case of a circle, the switches S W ”r, SWl.

All you have to do is turn off the SW.
To set the unit price to 25 yen, switch sw, ,
Both SWs and SWl will be turned on.

Next, the overall operation of the integrated power meter of the above embodiment will be explained according to the flowchart shown in FIG.

When the power is turned on and operation starts, CPU1
First, initial processing of the system is performed [step ST (
(hereinafter referred to as ST)1], then it is determined whether a counter reset is requested (Sr2).

Here, the counter reset request is a request to set the count value for counting the integrated power amount to O, and
, , are turned on, and a reset request flag is set by the key interrupt caused by this.

When this reset request flag is ON, the determination as to whether it is a counter reset request becomes YES. Sr2 judgment is Y
If it is ES, then the reset request flag is cleared (Sr3), the counter is reset, that is, the contents of the counter are set to 0 (5T4), the contents of the counter are converted to BCD (5T5), and the display stack is The operation is performed (S76). Here, by display stack operation, the contents of the counter are transferred to the display 4 via the segment recorder 6.
will be output and displayed as is.

Therefore, when the reset is performed, the accumulated power amount and usage charges up to that point are all set to 0.
0 will be displayed. After that, the process moves to ST7. On the other hand, if the reset request flag is 0 in Sr2, this determination becomes NO, and the process jumps to Sr7, where it is determined whether there is a display switching request.

Here, the display switching request means that when the switch SW1□ is turned on, a switching request flag is set due to an interrupt caused by the switch operation, and the switch SW1□ is turned on.
When z is operated, the switching request flag is turned on, and in this case, the determination is YES. If there is a switching request, the switching request flag is cleared with Sr1, and when the switch SW, 2 is turned on with the indicator light I7□ indicating kilowatt hours initially lit, the indicator light is turned on,
Performs LED display processing to light up the LED (Sr9), and performs BCD conversion processing for the charge calculated by the charge counter (Sr9).
T10) This converted usage fee data is operated on the display stack (STII) to display the usage fee in units of 100 yen on the display 4. In Sr7, if the indicator light L is lit before the display is switched, that is, if the display is the usage fee display, the indicator light L2 is switched to light in the LED display process of Sr9, and in the same way. 5TIO1STII BCD conversion processing and display stack operation are performed, display 4
Displays the cumulative amount of power used.

Next, the process moves to 5T12, and it is determined whether or not it is an execution request. This execution request is generated by a time interrupt provided separately every second, and when the condition for an execution request every second becomes YES, the process moves from 5TI2 to 5T13, and the execution output is set.

This running output set is set for testing. Next, 5T14 performs A/D conversion processing,
The current inputs detected by the current transformers CT and Cr2 respectively taken in from the signal conversion circuits 3a and 3b are taken in and stored, and then it is determined at 5T15 whether or not power integration is to be stopped (ST15). This power integration stop is detected before the integrated power amount counter counts up, and an error is displayed. If the power integration is to be stopped, the process moves to step 5T28, which will be described later, but if the power integration is not to be stopped, the inputs of each dip switch are taken in (ST16). Here, the dip switch input is the setting conditions of each current transformer CT, CT2 from switch SW to switch SW6, the additional amount of charges for switch SW7 to switch SWq, and the switch SW, o 3-phase 2-wire processing 0N10FF signal, etc.

Next, determine whether there is a 3-phase 2-wire setting error or not (5T17)
, in the case of a 3-phase 2-wire setting error, it also jumps to Sr18. The conditions for determining a 3-phase 2-wire setting error are that 3-phase 2-wire detection switch SW1° is ON, and switches SW1 and SW6 are OFF.
This is a case where N10FF matches. If there is no three-phase, two-wire setting error, then it is determined whether or not three-phase, two-wire detection has occurred (ST18). Here, for 3-phase 2-wire detection, switch S
The judgment is whether or not the switch SW1° is turned on. If the switch SW1° is not turned on, it is a normal two-system power detection process. Therefore, first the current transformer CT
(ST19), the current value taken in through the signal conversion circuit 3a and the input terminal AN is multiplied by the reference data corresponding to each setting condition, and the power connected to the current transformer CT at this point is calculated. The power of the grid is calculated (ST20). Then, after the reset, until then R
The currently calculated power amount is integrated into the cumulative power amount stored in the AM counter (ST21). Next, a set of calculations regarding current transformer CT2 is performed (ST22).
, Similarly, the power of the power system to which the current transformer CT2 is connected is calculated (ST23), and the current OCT is added to the integrated power amount related to the current transformers OCT+ and CT.

The electric energy of the electric power system related to is integrated, and the total integrated electric energy of the two systems is calculated (ST24).

This total integrated power amount is multiplied by the set unit price charge (standard charge of 18 yen plus the value set by switches SW7, SWl!, SW,) to calculate the usage charge (ST
25). Of course, this usage fee is also stored in the RAM within the CPUI. Next, it is determined whether the usage fee exceeds one million yen (5T26), and if it exceeds one million yen, Sr1
Jump to 8. If it is not over one million yen, perform BCD conversion processing (ST27), perform display stack operation,
The usage fee or integrated power amount is displayed on the display 4 according to the switching conditions (ST28). In this case, L
ED display processing is also performed (ST29).

The LED display process is the same as in the case described above, in that in the case of displaying the power rate, the indicator light is turned on, and in the case of the integrated power amount, the indicator light L2 is turned on. In addition, Sr18
, when an error occurs, such as when the display is not normal, when the integrated power value is stopped due to a drop, or when the judgment is YES that the value exceeds one million yen, a flashing light or a special display should be displayed to indicate each. become. When the LED display process of Sr11 is completed, the execution request flag that has been turned on until then is cleared (5T30), and backup judgment data is set (ST31).

Here, the backup judgment data is the CPUIORAM
This data is set to make a backup decision within the process, and is used in another routine to check whether the backup is sufficient. After that, the execution output is reset (5T32), the process returns to 5T26, and the same process is repeated sequentially. If there is a request to reset the counter, the processes from Sr1 to Sr1 are performed.
If there is a display switching request, the processes Sr1 to 5TII are performed, and if there is a request for execution every second, the processes 5T12 to Sr12 are repeated, and each
It calculates the power of each power system every second, integrates the currently calculated power amount with the previous integrated power amount, calculates charges for the total integrated power amount, and continues operation.

Note that in the above embodiment, two lines of electric power intake units each consisting of a current transformer and a signal conversion circuit are provided, but the present invention is not limited to this, and one line or three lines are provided.
More than one series may be provided.

In addition, the setting switches SW1 to SW each set two types of conditions for the current transformer, but they are fixed to one type, that is, the switches SW...1 and SW6 are omitted. Alternatively, three or more types of conditions may be selected and set depending on what is required.

Furthermore, in the above embodiment, to set the unit price, the standard charge is stored in the CPU and the additional amount is set using dip switches SW9, SW8, and SW9. However, the value set by the dip switch may be subtracted from the standard fee, or may be added to or subtracted from the standard fee.

Furthermore, a numeric keypad or digital switch may be provided, and the unit price itself may be input using the numeric keypad or digital switch.

In addition, in the above example, the integrated power amount and usage fee are:
The display is switched and displayed on the display 4, but these may be displayed in parallel with separate displays, and in addition to the integrated power amount and usage fee, the power amount can also be displayed in parallel. The display may be switched and displayed.

(F) Effects of the Invention According to this invention, since the unit price setting means for calculating the usage fee is provided, when the fee is revised, the fee can be revised by re-inputting the settings using the unit price setting means. can correspond to

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a circuit diagram of an integrating wattmeter showing an embodiment of the present invention, and FIG.
The figure is a circuit diagram showing the current transformer part connected to the terminals of the integrating wattmeter, Figure 4 is an external plan view of the integrating wattmeter, and Figure 5 shows the operation of the integrating wattmeter. It is a flow diagram for explanation. 1: CPU, 3a3b: Signal conversion circuit, 4: Display,
CT, -CT2: Current transformer, SW7 ・sw, -3W,
? Switch for setting unit price additional value. Patent distributor Tateishi Electric Co., Ltd. Agent Patent attorney Shigeru Nakamura Figure 3 Figure 1 b Denryokujo

Claims (1)

[Claims] (1) A current transformer that is connected to the power line under test and detects current, a signal conversion circuit that amplifies the current signal detected by this current transformer and converts it into a DC signal, and A power amount calculation means for calculating the power amount based on the current signal, an integrated power amount calculation means for integrating the calculated power amount, a unit price setting means for inputting and setting a unit price of usage fee, and the calculated integrated power amount. An integrating power meter comprising: a usage fee calculating means for calculating a usage fee by multiplying the amount by the input and set unit price; and a display means for digitally displaying the integrated power amount and the usage fee.