JPH0269675A - Watt-hour meter - Google Patents

Abstract

PURPOSE:To make a watt-hour meter generally usable to various systems to be measured with current transformer of various standards and, at the same time, to make the meter to display integrated electric energy and the power rate in digital values by providing a setting means which sets the voltage, phase number, specifications of used current transformer, of a system to be measured. CONSTITUTION:The voltage, phase number, and specifications of used current transformer of a system to be measured are previously selected and set by means of a setting means. A reading out means reads out reference data corresponding to the selected and set combination from a reference data storing means in accordance with the setting. On the other hand, current signals from the current transformer are inputted to an electric energy calculating means through a signal conversion circuit and the consumed electric energy is calculated by multiplying the current signals by the read-out reference data. Then an integrated electric energy calculating means calculates the integrated electric energy and an energy charge calculating means calculates the energy charge. Therefore, the integrated electric energy and the energy charge can be displayed in digital values.

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 an integrated 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 you use a current transformer and a signal conversion circuit to capture the current signal of the power line under test and calculate the amount of power based on this current signal, even if the same current signal is captured, the current specifications of the current transformer The amount of power consumed by the system under test varies depending on the voltage, number of phases, etc. of the system under test. Therefore, if the current specification of the current transformer, the voltage of the system under test, and the number of phases are fixed in the power calculation method, there is a problem that the integrating wattmeter can only be used for the system under test of the fixed standard. There is. In addition, in order for integrated wattmeters to become popular for general household use, they need to be provided at low cost and are required to be configured simply.

The present invention has been made in view of the above-mentioned problems, and can be used for general purpose in various systems to be measured and current transformer standards. The purpose is to provide an integrated wattmeter that can calculate the following.

(d) Means and operation for solving the problems The integrating wattmeter of the present invention includes a current transformer that is connected to the power line to be measured and detects the current, and a current signal that is detected by the current transformer. ．．
and a signal conversion circuit that converts it into a DC signal, and a power amount calculation that calculates power by multiplying the current signal from this signal conversion circuit by data determined by the current specification of the current transformer, the number of phases and voltage of the power line to be measured. means, an integrated power amount calculation means for integrating the calculated wattmeter, a usage fee calculation means for calculating a usage fee for the integrated power amount by performing a predetermined operation on the integrated power amount, and the integrated power amount and usage fee. a display means for digitally displaying the current transformer; and a setting means for individually selecting and setting the current specification, number of phases, and voltage of the current transformer; and a display means for individually selecting and setting the current specification, number of phases, and voltage of the current transformer; A reference data storage means for storing basic data for each combination in advance for quantity calculation; (See Figure 1)
.

In this integrated wattmeter, the voltage of the system to be measured, the number of phases, and the specifications of the current transformer to be used are selected and set in advance by the setting means (eg, 100V, single phase, 20A). Depending on this selection setting,
The reading means reads reference data corresponding to the combination of the selection settings from the reference data storage means.

On the other hand, a current corresponding to the load power flows through a current transformer coupled to the power line to be measured, and this current signal is amplified and converted to direct current by a signal conversion circuit, and is input to the power amount calculation means.

The power amount calculation means multiplies the current signal and the read reference data to calculate the power amount. Then, as time passes, this power amount is integrated by the integrated power calculation means, and the integrated power amount for a predetermined elapsed period is calculated. Further, the usage fee calculation means multiplies the integrated power amount by, for example, a preset unit price and calculates the usage fee.

Then, the calculated integrated power amount and usage fee are digitally displayed on the display means.

(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 integrated wattmeter has a CP (J1), a clock oscillator 2 for generating a synchronizing signal, and terminals P, P
Current transformer C externally connected to Z, (Plb,, P2b)
TI (Cr2) (see Figure 3), current transformer CT+
Convert the current detected by (CTz) into a signal and convert it to CP
A signal conversion circuit 3a (3b) input to the UI, a display (LED) 4 that displays a 4-digit numerical value, a finger drive circuit 6 that drives the display 4 with a finger, a segment decoder 7, a terminal P, , P receives a commercial voltage of 100■, and +1 is applied to each circuit.
A power supply circuit 7 that supplies power supply voltages such as 2V, -12V, +5V, a power supply voltage drop detection circuit 8 that detects a drop in power supply voltage, a backup circuit 9 that backs up the memory (RAM) in the CPUI, and a display. Light L + L 2
,... ■74 and various setting switches SW, ,S
It is composed of W2, . . . , SW1□.

The signal conversion circuit 3a includes an absolute value rectification circuit composed of operational amplifiers AM1 and AM2, and has the function of amplifying the signal corresponding to the detected current input through the terminals P11 and PZa, as well as performing full-wave rectification and smoothing. We are prepared. 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 the current (2) corresponding to the current flowing through the circuit under test detected by the current transformer CT into a DC component and inputs it to the CPUI.

The integrated power meter of this embodiment has a current transformer CT2 and a signal conversion circuit 3b arranged in parallel in addition to the current transformer CT and signal conversion circuit 3a 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,..., SW,. In both cases, dip switches are used, and among these, switch SW1
, SW2, and SW3 are setting switches related to the current transformer CT, and are 100V/20V of the power supply voltage of the load (system under test).
OV, single phase/three phase, and current transformer rating 2OA/
This is for setting the difference between 100A and 100A. Similarly, switches SW4, SW3, and SW6 are setting switches for current transformer CT2, each with a voltage of 100 V/200
This is for setting V, single phase/three phase, and 2OA/100A. Switch SW7, SWs, S
Wq is for adding and setting the unit price,
Regarding the unit price, a standard unit price of 18 yen is registered and stored in advance in the CPU I, and the yen to be added to and corrected is set using switches SW7, SW8, and SW9.

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. Switch SW1゜ is
This is for setting the two-phase detection mode in three phases. Switch SW, , is for reset, and switch S
W1□ is a switch for changing the display.

Switch sw, , sw, ,..., SW, □○N
The 10FF state is imported into the CPUI.

The CPU 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 SW, ..., S.
It has a function of reading reference data determined by the setting conditions of W, SW4, and SW6 from the built-in ROM and multiplying it by the current signal ■ 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, 2° A/10
The following eight types are stored depending on the 0A.

However, 256 is the number of bits of the A/D converter, and the power factor is 0.
．． It is fixed at 85.

These reference data DI, ..., D8 are the ON10 F F of the switches SW, ..., SW6 shown in FIG.
They are each read out from the ROM according to the mode shown in FIG.

The CPUI also has a function to calculate the cumulative power amount by integrating the power amount, a function to calculate the usage fee by multiplying the calculated cumulative power amount by the set unit price, switch SW, 0N of 2.
It has a function of switching and displaying the integrated power amount and usage fee on the display 4 according to the 10FF setting status.

The indicator light lights up when the display changes to fare. This indicator light has a weight of 100 yen. Therefore, if the indicator light is on and the display 4 shows 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 L3,
L4 has current transformers CT, , and C70 specifications of 10O.
A, and lights up when switches SW3 and SW6 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,
The indicator light 7, L2, reset button SW, display switching button SW1□, are arranged so that they can be seen visually.
The other circuit sections shown in FIG. 2 are housed within the main body case 20. Most buttons SW +, -, SW
12- is covered by the transparent cover 20a of the main body case 20, and the reset buttons SW, ... cannot be operated unless the main body case 20a is removed, and the display switching button SW1□3 can be operated by inserting a bar etc. through the small hole 20b. It is designed so that it cannot be turned on/off unless it is inserted and operated, which prevents erroneous settings caused by easy touching.

When using this embodiment of the integrated power meter, the terminal P Ias
A current transformer CT connected to P Za, and a terminal P lb
The current transformers CT2 connected to sPZb are each pushed through and connected to one of the load power lines to be measured (see, for example, FIG. 3). Then, the settings regarding each current transformer CT1, C70 are set by switches SW1, ..., SW6.
Do it with In this case, the settings for current transformer CT and current transformer CT2 are made individually and independently, and if the power systems are different,
There may be different settings for double flow devices.

Therefore, for current transformer CT, switch SW1 is 1
It is also possible to set the current transformer CT2 to the 00V side, and set the switch SW by the current transformer CT2 to 200V.Also, while the setting by the switch SW2 is three-phase, the switch SW.

There is no problem in the setting even if it is single phase. However, this is a case where the two-way current transformers CT and C70 are each coupled to one of the same three-phase load power lines, and each series detects a current signal corresponding to the amount of electric power, and the electric power obtained based on this is detected. In the case of averaging the amount, that is, in the case of two-phase detection in three phases when the switch SW,0 is turned on, it is necessary that the current transformers CT, , C70 are set under the same conditions.

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 yen, it is sufficient to turn off the switches SVI/l,...SW, and on the other hand, if the unit price is 25
When setting to circle, switch SW7, SW8, SW
, both 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.

The power is turned on and operation starts.CPU1
First, initialize the system (STEP ST).
(hereinafter referred to as ST)1], then it is determined whether a counter reset is requested (Sr1).

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 the reset request is for the power counter becomes YES. Judgment of Sr1 is Y
If it is ES, then the reset request flag is cleared (Sr3), counter reset processing is performed, that is, the contents of the counter are set to 0 (5T4), the contents of the counter are converted to BCD (5T5), and display stack operation is performed. (Sr1). Here, by the display stack operation, the contents of the output counter are output to the display 4 via the segment recorder 6, and are displayed as they are.

Therefore, when the reset has been performed, the accumulated power amount and usage charges up to that point will all be O.
0 will be displayed. After that, the process moves to ST7. On the other hand, if the reset request flag is O in ST2, this determination becomes NO, and the process jumps to ST7, where it is determined whether or not there is a display switching request.

Here, the display switching request means that when the switch SWl□ is turned on, a switching request flag is set due to an interrupt caused by the switch operation, and the switching request flag is set by the switch SW1□.
When □ is operated, the switching request flag is turned ON, and in this case, the determination becomes YES. If there is a switching request, the switching request flag is cleared in ST8, and with the indicator light L2 indicating kilowatt hours initially lit,
When the switch SW, 2 is turned on, L F, D display processing is performed to light up the indicator light L+ (ST9), and BCD conversion processing of the charge calculated by the charge counter is performed (ST
10) 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 ST7, before switching the display,
If the indicator light L1 is lit, that is, the display is the usage fee display, the indicator light L2 is turned on in the LED display process of ST9.
Switch to ST10. in the same way. STI 1(7)B
CD conversion processing and display stack operation are performed, and the integrated power consumption is displayed on the display 4.

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 CT z taken in from the signal conversion circuits 3a and 3b are respectively taken in and stored, and then it is determined at 5T15 whether or not the power integration is stopped (ST15). . This power integration chart detects and displays an error before the integrated power counter counts up. If the power integration is stopped, the process moves to 5T2B, which will be described later.
If the power integration is not stopped, the human power of each dip switch is taken in (ST16). Here, the dip switch input refers to the setting conditions of each current transformer CT, C70 from switch SWI to switch SWb, and switch S
W'? , . . . , the additional amount of charges for SW, and the ON10 FF signal of the three-phase two-wire processing of switch SW1°. Next, check whether there is a 3-phase 2-wire setting error or not.
T17), in case of 3-phase 2-wire setting error, 5T
Fly to 28.

The condition for determining a 3-phase 2-wire setting error is when the 3-phase 2-wire detection switch SW1° matches the on/off states of the switches SW:l and SWb. If it is not a 3-phase 2-wire setting error, then it is determined whether 3-phase 2-wire detection is detected (S
T18). Here, the three-phase two-wire detection is a determination as to whether or not the switch SW1° is turned on.
, , are not turned on, it is a normal two-series power amount detection process, and therefore, first, a calculation set is performed for the current transformer CT (ST19), and power calculation is performed (ST20).

This power calculation is performed by sequentially outputting the corresponding reference data from the ROM based on the setting data of the switches SW1, .

The reference data D is multiplied by the current value . For example, if switches sw, , sw2, and SW are all ON, the settings are 200■, 3-phase, 100A
In this case, the reference data Dll is read out, and the electric energy ■×Dl+ is calculated.

After the reset, the currently calculated power amount is integrated into the cumulative power amount stored in the RAM counter up to that point (ST21). Next, a set of calculations regarding the current transformer CT z is performed (ST22), and similarly, power calculations for the power system to which the current transformer CT is connected are performed (ST2).
3) The integrated power amount of the current power system related to C70 is integrated with the integrated power amount of the current transformer OCT and CT z so far, and the total integrated power amount of the two series is calculated (ST24). This total integrated power amount is multiplied by the set unit price to calculate the usage fee (ST25). Of course, this usage fee is also stored in the RAM within the CPUI. Next, check 5T to determine whether the usage fee exceeds 1 million yen.
26), if the amount exceeds one million yen, jump to Sr28.

If it is not over one million yen, after performing BCD conversion processing (Sr27), a display stack operation is performed and the usage fee or electric power amount is displayed on the display 4 according to the switching conditions (Sr28). In this case, LED display processing is also performed in the same way (Sr29). 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 L2 is turned on, and in the case of the integrated power amount, the indicator light L2 is turned on. In addition, in 5T28, if the display is not normal,
In other words, if the integrated power value is stopped, it is determined whether it is over 1 million yen Y
When an error occurs, such as in the case of ES, a blinking light or a special display is performed to indicate the respective conditions. When the LED display process of Sr21 is completed, the execution request flag that was turned on until then is cleared.
0), set backup judgment data (Sr31
). Here, the backup judgment data is the CPU RA
This is data set in M to make a backup decision, 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 Sr2, and the same process is repeated sequentially. If there is a request to reset the counter, the process from Sr2 to Sr6 is performed.
If there is a display switching request, the processes Sr7 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.

In the above embodiment, two lines of the current signal acquisition unit consisting of the current transformer and the signal conversion circuit are provided, but the present invention is not limited to this, and the present invention is not limited to this. It may be.

In addition, the setting switches SW to SW6 each set two types of conditions for the current transformer, but depending on what is required, three or more types of conditions may be selected and set. good.

In addition, in the above embodiment, to calculate the usage fee,
The integrated power amount is multiplied by the set unit price, but a price table corresponding to the integrated power amount is registered in advance in the CPU storage device, and this is selectively read out. It's okay.

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 the switching can also be done by displaying the amount of electricity in addition to the cumulative amount of electricity and the usage fee. The display may be switched and displayed.

(f) Effects of the Invention According to the present invention, since the present invention is equipped with a setting means for individually switching and setting the specifications of the current transformer, the number of phases of the system under test, and the voltage, the state of the system under test, that is, the load, etc. Accordingly, it is possible to calculate the electric power amount appropriately, and therefore, it is possible to obtain a highly versatile integrating power meter that can be used in various systems to be measured.

In addition, the reference data corresponding to the combination of the current transformer specifications, the number of phases of the measured system, and the voltage set by the setting means is read out from the storage means, and the current signal taken in is multiplied by the reference data to generate the electric power. Since the amount of electricity is calculated, calculations can be made quickly, and in terms of configuration, only a storage means for storing a small amount of reference data is required, making it simple and eliminating the need for complicated calculations for calculating the amount of electricity. Software is also not required, making it possible to provide an integrated power meter that is inexpensive overall.

[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. A flowchart for explanation, FIG. 6, shows the switches sw, , s of the integrated power meter.
w, , . . . is a diagram showing the relationship between the 0N10FF state of SWb and reference data. 1: CPU, 3a-3b: Signal conversion circuit, 4: Display, CT, -CT2: Current transformer, SW, SW z
,... S W b : Setting switch related to the system under test. Patent Applicant Tateishi Electric Co., Ltd. Agent Patent Attorney Shin Nakamura Shigeru Nakamura Figure Figure h Figure SW++a 0b 0a Figure 1'' → 0N O1 Order OFF

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 power by multiplying the current signal by data determined by the current specification of the current transformer, the number of phases and voltage of the power line to be measured; and an integrated power amount calculation means for integrating the calculated power amount. , a usage fee calculation means for calculating a usage fee for the integrated power amount by performing a predetermined calculation on the integrated power amount;
The integrating wattmeter includes a display means for digitally displaying the integrated power amount and the usage fee, and a setting means for individually selecting and setting the current specification, number of phases, and voltage of the current transformer, and a setting means for individually selecting and setting the current specification, the number of phases, and a standard data storage means for storing in advance standard data for calculating electric energy corresponding to the combination of number and voltage for each combination; and in response to the combination of current specification, number of phases and voltage set by the setting means, reading means for reading reference data corresponding to the combination from the reference data storage means, and the power amount calculation means calculating the power amount by multiplying the current signal and the read reference data. Integrating power meter.