JP3029320B2 - Automatic adjustment device for electronic wattmeter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[Object of the Invention]

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic adjusting device for an electronic wattmeter for automatically adjusting an error in measured power of the electronic wattmeter.

[0003]

2. Description of the Related Art Measurement of an error in an electronic watt-hour meter
A comparison method called RC method is adopted. In this system, as shown in FIG. 3, the power generated from the power source 2 is supplied to both the meter 1 to be adjusted and the master meter 3 adjusted by another highly sensitive measuring device. You. Adjusted meter 1 and master meter 3
Measures the power and outputs a count pulse and a reference pulse proportional to the power, respectively. The metering pulse from the adjusted meter 1 and the reference pulse from the master meter 3 are counted by the adjusted meter counter 42 and the master meter counter 41 of the RC counter 4, respectively, for a predetermined period. The RC counter 4 is a counter 4 for the meter to be adjusted.
2 and the respective counter values of the master meter counter 41 are displayed, and both the count display values are calculated according to the following formula, and the count display value of the metering pulse of the adjusted meter 1 with respect to the count display value of the reference pulse of the master meter 3 Is calculated.

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

FIG. 4 is a block diagram showing a circuit configuration of the meter 1 to be adjusted. In the figure, the current and voltage components of the power to be measured are respectively a current transformer (CT) 11
And a signal proportional to the current value and the voltage value detected by the transformer (PT) 12. The signal from the current transformer 11 and the signal from the transformer 12 via the variable resistor 17 are multiplied by a power-frequency (W / F) converter 13 and converted into a pulse number proportional to the multiplied value. This pulse signal is frequency-divided by a frequency divider 14 to an appropriate frequency, which is then output to the RC counter 4 via an output unit 18 and counted by a counter 15, and the counted value is displayed on a display unit. At 16, the measured power is displayed.

In order to adjust the meter to be adjusted 1 configured as described above by the RC method, after the first error measurement, the RC
An error is calculated from the display value of the counter 4, and based on the error, the variable resistor 1 connected to the output of the transformer 12 is calculated.
After manually adjusting 7, make an error measurement again, check that the error is within the specified range, and if it is out of the specified range, repeat the adjustment and error measurement again until the error is within the specified range. We are making adjustments to confirm that there are some and then exit.

[0007]

In the above-described conventional method, since the error is eliminated while manually adjusting the variable resistor, the adjustment takes time and effort, and is inefficient and uneconomical. There is a problem that there is.

[0008] The present invention has been made in view of the above,
It is an object of the present invention to provide an electronic watt-hour automatic adjustment device capable of adjusting an error of the electronic watt-hour in a short time and accurately.

[Structure of the Invention]

[0010]

Means for Solving the Problems] To achieve the above object, an automatic adjustment device for an electronic watt-hour meter of the present invention, the power converting power to be measured to the signal of the corresponding frequency - a frequency conversion unit, An electronic watt-hour meter having frequency dividing means for frequency-dividing a signal from said power-frequency converting means and counting means for counting a frequency-divided signal from said frequency dividing means and displaying it as power. The power output from the means is supplied to the power-to-frequency conversion means and converted into a signal of a corresponding frequency, and the frequency of the signal is converted by the power supplied from the reference power generation means to the power-to-frequency conversion means. Sa
The gist of the present invention is to include an error calculating means for calculating an error between the two frequencies by comparing with the frequency of the obtained signal, and a correcting means for correcting the counting means based on the frequency error from the error calculating means.

[0011]

[0012]

According to the automatic electric energy meter of the present invention,
The power output from the reference power generation means is supplied to the power-frequency conversion means and converted into a frequency. Is calculated, and the counting means is corrected based on this error.

[0013]

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an automatic adjusting device for an electronic watt-hour meter according to one embodiment of the present invention. The automatic adjustment device for the electronic watt-hour meter shown in FIG.
The power generation source 2 and the master meter 3 are the same as those shown in FIG. 2, and the adjusted meter 5 which is an electronic wattmeter whose error is to be adjusted. The power generated from the power generation source 2 is the master meter 3 and the adjusted meter. 5 is supplied to both. The power source 2 does not require any special precision and stability, and the master meter 3 is adjusted by another high-precision measuring device.

The meter to be adjusted 5 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) 51 and a transformer (PT) 52, respectively. The signal is converted into a signal proportional to the value and supplied to a power-frequency (W / F) converter 53. Although the variable resistor as shown in FIG. 4 is not connected to the output of the transformer 52, the automatic adjusting device of the electronic watt-hour meter does not need to adjust the variable resistor as in the related art. ing.

The power-frequency converter 53 includes a current transformer 5
1 is multiplied by a signal proportional to the current value from the transformer 52 and a signal proportional to the voltage value from the transformer 52, and the output signal is converted into a signal of a corresponding frequency and supplied to the frequency divider 55. Error calculation unit 56 using the signal as a weighing pulse signal
To supply. The frequency divider 55 includes the power-frequency converter 5
The frequency of the signal from No. 3 is divided into a signal of a frequency that is easy to count and supplied to the counter 59. The counter 59 counts the frequency of the signal from the frequency divider 55, supplies the counting result to the display unit 50 via the correction unit 61, and displays it as power.

On the other hand, the master meter 3 measures the power supplied from the power generation source 2, converts the measured power into a reference pulse signal having a pulse number proportional to the power amount, and supplies the reference pulse signal to the error calculator 56 of the meter 5 to be adjusted. Supply.

The error calculating section 56 compares the count pulse signal supplied from the power-frequency converter 53 of the meter 5 to be adjusted with the reference pulse signal supplied from the master meter 3 to determine an error between the two pulse signals. That is, an error between the reference pulse signal representing the electric energy measured by the master meter 3 and the measuring pulse signal representing the electric energy measured by the adjusted meter 5 as shown in the above-mentioned equation (1) is calculated. The obtained error signal is supplied to the correction coefficient setting unit 57.

The correction coefficient setting section 57 sets a correction coefficient for canceling the error based on the error supplied from the error calculation section 56, and supplies the correction coefficient to the correction coefficient storage section 58 for storage. . The correction coefficient storage unit 58
Is constituted by, for example, an EEPROM or the like so that the stored correction coefficient is not erased due to a power failure or the like.

The correction coefficient storage section 58 supplies the stored correction coefficient to the correction section 61, and the correction section 61 multiplies the count value from the counter 59 by the correction coefficient to generate a counter 59.
The corrected count value is supplied to the display unit 50 and displayed as a correctly adjusted and corrected correct power value. The correction coefficient storage unit 58 initially stores a correction coefficient as a correction coefficient.
From 1.00 to 1.00 are stored. In this case, error correction is not performed.

FIG. 2 is a block diagram showing a configuration of an automatic adjusting device for an electronic watt-hour meter according to another embodiment of the present invention. In the embodiment shown in the drawing, the current transformer 51, the transformer 52, the power-frequency converter 53, and the error calculation of the power generation source 2, the master meter 3, and the adjusted meter 5 in the embodiment shown in FIG. The configuration and operation of the parts related to the part 56 are exactly the same, and the same reference numerals are shown.

In the embodiment shown in FIG. 2, the frequency division ratio of the frequency divider 67 for dividing the frequency of the signal output from the power-frequency converter 53 is controlled, thereby performing error correction. Things. More specifically, the frequency error calculated by the error calculation unit 56 is divided by the frequency division ratio setting unit 63
The frequency division ratio setting unit 63 sets a frequency division ratio based on the error to cancel the error, and stores the frequency division ratio in the frequency division ratio storage unit 65.

The frequency division ratio storage unit 65 is composed of, for example, an EEPROM or the like in preparation for a power failure or the like, like the correction coefficient storage unit 58, but supplies the stored frequency division ratio to the frequency divider 67.
The frequency divider 67 corrects the frequency division operation by multiplying the frequency division operation supplied from the frequency division ratio storage unit 65 by the frequency division operation, and outputs the signal of the corrected frequency division result via the AND circuit 69 to the counter. 59
To supply. The counter 59 counts the signal having the corrected frequency division result from the frequency divider 67 via the AND circuit 69, supplies the counted result to the display unit 50, and corrects and corrects the correct power amount. Display as

The AND circuit 69 is provided with a frequency division ratio storage unit 65.
When the frequency division ratio is stored in the frequency division ratio storage unit 65, the output signal from the frequency divider 67 is inhibited if the frequency division ratio is not stored in the frequency division ratio storage unit 65. It is supposed to. Specifically, until the division ratio is stored from the division ratio setting unit 63, the division ratio storage unit 65
Stores a frequency division ratio of, for example, 1/1, so that error correction is not performed, and the AND circuit 69
Is closed, and the signal from the frequency divider 67 is not supplied to the counter 59.

Although each of the above embodiments is mainly composed of hardware,
Even if this is replaced with software, the same configuration can be obtained.

When the master meter 3 has a known error, the error of the master meter 3 may be set in the error calculating section 56 so as to cancel the error.

Further, in the embodiment shown in FIG. 1, the correction coefficient is set as 1.00, and the master meter 3 performs the decimal representation of the significant digits with the required precision. It may be changed to a fraction expression such as 95. When the error-corrected count value is displayed, the corrected count may also be displayed.

[0029]

As described above, according to the present invention,
The power output from the reference power generation means is supplied to the power-frequency conversion means and converted into a frequency. Is calculated, and the frequency division ratio of the counting means or the frequency dividing means is corrected based on this error, so that the complicated work of manually adjusting the variable resistor as in the related art is unnecessary, and the adjustment cost and the adjustment time are reduced. Work errors can be prevented, and efficiency and economy can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a circuit configuration of an automatic adjustment device for an electronic watt-hour meter according to one embodiment of the present invention.

FIG. 2 is a block diagram showing a circuit configuration of an automatic adjusting device for an electronic watt-hour meter according to another embodiment of the present invention.

FIG. 3 is a configuration diagram of a conventional automatic adjustment device for an electronic watt-hour meter.

FIG. 4 is a configuration diagram of an electronic watt-hour meter used in the automatic adjustment device for the electronic watt-hour meter of FIG. 3;

[Description of Signs] 2 Power generation source 3 Master meter 5 Meter to be adjusted 53 Power-frequency converter 55 Frequency divider 56 Error calculation unit 57 Correction coefficient setting unit 59 Counter 61 Correction unit 63 Division ratio setting unit 67 Frequency divider

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mitsuhiro Sakoyama 70, Yanagicho, Saiwai-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Yanagimachi Plant, Toshiba Corporation (56) References JP-A-4-282463 (JP, A) JP-A-Hei 2-165065 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01R 11/00-11/66 G01R 21/00-22/04

Claims (1)

(57) [Claims] 1. A power converting power to be measured to the signal of the corresponding frequency - a frequency conversion unit, said power - dividing of the signal from the frequency converter from the frequency dividing means and frequency dividing means for dividing An electronic watt-hour meter having counting means for counting a signal and displaying it as electric power, wherein the electric power output from the reference electric power generating means is supplied to the electric power-frequency converting means and converted into a signal of a corresponding frequency. ,
The frequency of the signal is converted from the reference power generation means to the power−
Error calculating means for calculating the error between the two frequencies by comparing the frequency of the power supplied to the frequency converting means with the frequency of the signal, and correcting means for correcting the counting means based on the frequency error from the error calculating means An automatic adjustment device for an electronic watt-hour meter, comprising: