JPH0727842A - Electronic watt-hour meter - Google Patents

Abstract

PURPOSE:To obtain an electronic watt-hour meter from which errors can be easily measured and error-measured results can be easily recognized. CONSTITUTION:A master meter 3 sends a reference electric power signal which is converted corresponding to a signal obtained from an electric power generating source 2 to the input section 9 of a meter 1 to be measured. In the meter 1, the signal corresponding to electric power is obtained by performing multiplication on the signal obtained from the source 2 by means of a multiplier 6 through a CT (current transformer) 4 and PT (transformer) 5 and a CPU 7 calculates an error by comparing the output signal of the input section 9 obtained through a counter 10 with the output signal of the multiplier 6 and displays the calculated results in a displaying section 8.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to an electronic watt hour meter.

[0002]

2. Description of the Related Art An error measurement in an electronic watt hour meter is
Generally, a comparison method called RC method is adopted. In this method, as shown in FIG. 3, the electric power generated from the electric power generation source 2 is adjusted by a measured meter (electronic watt hour meter) 30 to be subjected to error measurement and another highly sensitive measuring device. It is supplied to both of the master masters 3 that have been processed.

The measured meter 30 and the master meter 3 are
The power is measured, and a metering pulse and a reference pulse proportional to the power are output. The measured pulse from the measured meter 30 and the reference pulse from the master meter 3 are counted by the measured meter counter 21 and the master meter counter 22 of the RC counter 20 for a predetermined period and output. . The output count values of the counter 21 for the measured meter and the counter 22 for the master meter are the CPU 41 of the display terminal 40.
The calculated values of both counting values are calculated according to the following equation (1), and the error of the counting value of the measuring pulse of the measured meter 30 with respect to the counting value of the reference pulse of the master meter 3 is calculated. The display terminal 40 displays the calculation result of the CPU 41 on the display unit 42.

[0004]

[Equation 1] Error (%) = (measured pulse count value−reference pulse count value) × 100 / (reference pulse count value) (1) In this method, the accuracy of the master meter 3 affects the measurement accuracy. The power generation source 2 does not require high accuracy and stability, and the generated power may vary.

FIG. 4 is a block diagram showing a circuit configuration of the measured meter 30. In the figure, the current and voltage components of the power to be measured are converted into signals proportional to the current and voltage values detected by the current transformer (CT) 31 and the transformer (PT) 32, respectively. The signal from the current transformer 31 and the signal from the transformer 32 are the power-frequency (W / F) converter.
It is multiplied by a converter 33 and converted into a pulse number proportional to the multiplication value. This pulse signal is frequency-divided by the frequency divider 34 into an appropriate frequency that can be easily counted, and then the RC counter 20 is output through the output section 35.
Is output to the counter 36 and is counted by the counter 36, and the count value is displayed on the display unit 37 as the measured power amount.

[0006]

However, in such an electronic watt-hour meter, the RC counter 20 and the display terminal 40 in which the dedicated software is incorporated are required to measure the error, and therefore the error measurement is performed. Sometimes it is necessary to move the measured meter 30 to the place where these devices are installed. Therefore, the error measurement work was inefficient and uneconomical.

In recent years, the number of watt-hour meters using other multiplication principles that do not use a W / F converter has been increasing, and in particular, digitization of measured data has been greatly advanced. In such a case, normally, the pulse output cannot be obtained from the measured meter 30 side, and it is difficult to measure the error using the pulse from the measured meter 30, and It was not possible to know the error value at measurement meter 30. An object of the present invention is to provide an electronic watt-hour meter that can easily perform error measurement and can recognize the error measurement result.

[0008]

In order to achieve the above object, in the first invention, the first conversion means for converting into a signal corresponding to the power to be measured, and the conversion corresponding to the reference power. It comprises an input means for inputting a signal, an error calculating means for calculating an error by comparing the output signals from the input means and the first converting means, and a display means for displaying a calculation result by the error calculating means. Use as a summary.

In the second invention, the first converting means for converting into a signal corresponding to the power to be measured, the input means for inputting the converted signal corresponding to the reference power, and the input means. The gist is that the output signal from the first conversion means is compared to calculate an error, and the output means outputs the calculation result of the error calculation means to the outside.

[0010]

With such a structure, in the first invention, when the error calculating means calculates the error of the output signal of the first converting means with respect to the output signal of the input means, the calculation result is displayed on the display means. Therefore, the error measurement can be easily performed, and the error measurement result can be recognized by the instrument body.

Further, in the second invention, when the error calculating means calculates the error of the output signal of the first converting means with respect to the output signal of the input means, the calculation result is output to the outside by the output means. The error measurement can be performed easily, and the error measurement result can be recognized even in a remote place.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an electronic watt hour meter of the present invention. In the figure, it is composed of a measured meter 1 which is an electronic watt-hour meter for measuring an error and the same power generation source 2 and master meter 3 as shown in FIG. The generated power is supplied to both the master meter 3 and the measured meter 1. It is assumed that the power generation source 2 does not require special precision and stability, and that the master meter 3 is adjusted by another high precision measuring device.

The meter to be measured 1 supplies a current component and a voltage component of the power to be measured from the power generation source 2 to a current transformer (CT) 4 and a transformer (PT) 5, respectively. The signal is converted into a signal proportional to the value and the voltage value and supplied to the multiplier 6. The multiplier 6 multiplies the signal proportional to the current value from the current transformer 4 by the signal proportional to the voltage value from the transformer 5, and supplies the output signal to the CPU 7. At this time, the multiplier 6 converts the frequency into a frequency by a W / F converter and outputs it through a counter, for example,
Alternatively, it indicates that the signal proportional to the current value from the current transformer 4 and the signal proportional to the voltage value from the transformer 5 are respectively A / D converted and multiplied to output the result.

On the other hand, the master meter 3 measures the electric power supplied from the electric power source 2, converts it into a reference pulse signal having a pulse frequency proportional to the electric power, and inputs it to the measured meter 1 by the input section 9. Is entered. The input reference pulse signal is counted by the counter 10 and supplied to the CPU 7, where C
The PU 7 performs an error calculation as in the above-mentioned formula (1). The calculation result is displayed on the display unit 8 as an error value.

In such a structure, the measured data 1
Since the CPU 7 and the display unit 8 are provided in the measured data, the error can be measured in the measured data 1 and the error value can be measured.
Can be recognized from. Therefore, the RC counter and the display terminal, which were required for the conventional error measurement, are not required, and the error measurement can be performed regardless of whether the pulse output can be obtained from the measured device 1 or not. The measurement work becomes efficient and economical.

FIG. 2 is a block diagram showing another embodiment of the electronic watt hour meter of the present invention. In the figure, an output unit 11 is provided on the output side of the CPU 7 in addition to the configuration of the above embodiment. The output unit 11 outputs the error calculation result of the CPU 7 as, for example, a serial signal to an external device, for example, a device installed at a remote place.

In such a structure, in addition to the effects of the above-described embodiment, there is an effect that an error value can be recognized even by a device installed at a remote place. If only the external device needs to be able to recognize the error value, the display unit 8 may not be provided and only the output unit 11 may be provided.

[0018]

As described above, according to the present invention, a signal corresponding to the power to be measured obtained from the first conversion means,
From the signal corresponding to the reference power obtained from the input means, the error calculation means performs a comparison operation to calculate the error,
Since the calculation result is displayed or output to the outside, the error measurement can be easily performed, and the error measurement result can be recognized by the device under test or the external device.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an error measurement of an electronic watt hour meter showing an embodiment of the present invention.

FIG. 2 is a diagram for explaining error measurement of an electronic watt hour meter showing another embodiment of the present invention.

FIG. 3 is a diagram for explaining error measurement of a conventional electronic watt hour meter.

FIG. 4 is a block diagram of the measured meter 30 shown in FIG.

[Explanation of symbols]

3 ... Master meter, 6 ... Multiplier, 7 ... CPU, 8 ... Display section, 9 ... Input section

Claims (2)

[Claims] 1. A first conversion means for converting into a signal corresponding to the power to be measured, an input means for inputting a signal converted corresponding to the reference power, the input means and the first An electronic watt-hour meter having an error calculating unit that compares an output signal from the converting unit to calculate an error, and a display unit that displays a calculation result of the error calculating unit. 2. A first conversion means for converting into a signal corresponding to the power to be measured, an input means for inputting the signal converted corresponding to the reference power, the input means and the first An electronic watt-hour meter having an error calculating unit that compares an output signal from the converting unit to calculate an error, and an output unit that outputs the calculation result of the error calculating unit to the outside.