KR101179119B1 - Apparatus and method for metering discrete signals - Google Patents

Abstract

PURPOSE: An apparatus for measuring discrete signals and a method thereof are provided to precisely measure the discrete signals by automatically controlling the interval of a measurement size according to signal size when a continuous signal is changed into the discrete signal. CONSTITUTION: An A/D converter(140) comprises a measurement size interval setting part(141) and a hardware resolving power part(142). An input unit(110) inputs information including a metering method and a metering kind which is necessary for measurement information. A second MOF(Metering Out Fit) output signal part(120) determines a second MOF output signal by a PT ratio and a CT ratio based on the information inputted through the input unit. A second MOF output signal measurement range setting part(130) sets the measurement range of the second MOF output signal according to a kind of hardware.

Description

Discrete signal metering method and apparatus {APPARATUS AND METHOD FOR METERING DISCRETE SIGNALS}

The present invention relates to a method and apparatus for measuring discrete signals, and more particularly, to a method for measuring high precision discrete signals that minimizes measurement errors according to the magnitude of a measurement signal when measuring by converting a continuous signal of voltage and current into a discrete signal, and Relates to a device.

The precision of the metering device is determined by the continuous signal (analog) and the discrete signal (digital). In the power system, the instrument transformer (Metering Out Fit, hereinafter referred to as MOF) is installed to convert the 22.9kV high voltage on the primary side to 110V on the secondary side, and to convert the primary large current to small currents below the secondary 5A, such as power meters and protection relays. It is used as a continuous signal, and the discrete signal is measured by converting the continuous signal into a discrete signal in an internal electronic circuit device such as a power meter and a protection relay.

Taking the measurement error of the electricity meter as an example, the power generation customer installs and measures the power receiving meter and the power generation meter because the flow direction of the receiving power and the generating power are different.

Power meters measure transformer losses and on-site loads, while power meters measure power loads.

Power reception and power generation meters are used in the same line with two meters in series with the same MOF, and the MOF ratio is determined by the customer's transformer capacity or the transmission and reception contract capacity.

Therefore, the receiving power meter and the generating power meter using the same MOF magnification have a metering error in the unpowered meter due to the difference between the transformer loss power at no load and the power at power generation.

The reason is that the same MOF magnification of the receiving power and the generating power is used, so that the weighing error is generated by the continuous signal and the discrete signal, and the discrete signal has a relative resolution at no load because the hardware resolution capability, that is, the interval of the measurement size is fixed. Weighing error occurs.

In general, if the interval between the measurement size is narrow and the sampling interval is short, depending on the hardware resolution capability, the high performance measurement device is required. If the measurement size and time interval are small, expensive equipment performance with large data storage capacity is required.

Therefore, in order to minimize weighing errors, power meters, protection relays, and the like, which are commonly used in industrial fields, need a method of automatically adjusting a measuring range when a measurement signal such as a load current changes.

As mentioned above, the power generation customers measure the received power and the generated power at the same MOF magnification because the power generation difference between the received power and the generated power differs. Therefore, there is a need for a method for improving errors at no load or light load.

In addition, since the protection relay must measure a current several tens more times than the normal current or a current lower than the normal current when the line breaks down, there is a problem in that a measurement error occurs as much as the measurement interval of the discrete signal if the interval of the signal measurement size is fixed.

Accordingly, Korean Laid-Open Patent Publication No. 2006-0063829 (a current non-error test method and apparatus for live state transformers) discloses a method of detecting a failure of a transformer by finding a measurement error of a secondary current. It is only to find out the weighing error, and has not suggested any way to improve the error.

Korean Laid-Open Patent No. 2006-0063829, 'Current non-error test method and apparatus for live state transformer'

In order to solve the above problems of the prior art, the present invention provides a high precision discrete signal metering method and apparatus capable of increasing the measurement accuracy when measuring a continuous signal as a discrete signal.

The objects of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood from the following description.

In order to achieve the above object, the discrete signal metering apparatus according to an aspect of the present invention, MOF secondary output for setting the measurement range of the metering Out Fit (MOF) secondary output signal according to the type of hardware A signal measuring range setting unit, an amplification ratio calculating unit for calculating an amplification ratio using a predetermined magnification for each of the MOF secondary output signal value and DC / AC within the set measuring range, the set measuring range and the calculated amplification If the input signal input to the automatic amplification unit for calculating the automatic amplification ratio using the ratio, and outputs the calculated automatic amplification ratio, and the A / D conversion unit for converting the continuous signal into a discrete signal is less than a predetermined reference value, An input magnification adjusting unit for amplifying the magnitude of the input signal based on the output automatic amplification ratio and the output automatic amplification ratio within the set automatic amplification range. And an output magnification adjusting unit for adjusting an interval of the measurement size output from the A / D converter.

In one aspect of the present invention, the MOF secondary output signal measurement range setting unit sets to have a margin of a predetermined range in consideration of the measurement range of the set MOF secondary output signal.

In addition, in one aspect of the present invention, the amplification ratio calculating unit sets the amplification ratio to a maximum of 5 times in the case of a power meter, up to 50 times in the case of a protective relay.

In addition, in one aspect of the present invention, the amplification ratio calculator calculates the amplification ratio by multiplying the MOF secondary output signal value by a predetermined magnification for each DC / AC, the predetermined magnification for each DC / AC, DC Is 1 for ac and 2 for ac.

Further, in one aspect of the present invention, the amplification ratio calculator recalculates the calculated amplification ratio according to the sampled time.

In addition, in one aspect of the present invention, the automatic amplifying unit divides the maximum value of the measurement range of the secondary output signal by the amplification ratio value using a two-terminal division function, thereby dividing the signal of the automatic amplification ratio according to the load. Output

In addition, in one aspect of the present invention, the automatic amplifying unit sets a finite number of digits for the value of the output automatic amplification ratio.

In addition, in one aspect of the present invention, the automatic amplifying unit for measuring the load current in the steady state is a maximum number of digits of the finite number of points, the metering device for measuring the fault current in the transient state of the finite number of digits Set to minimum 1 and maximum 3

In addition, in one aspect of the present invention, the output magnification adjusting unit attenuates the output measurement size interval at a ratio of the automatic amplification ratio to correct an error with respect to the measurement size interval.

In order to achieve the above object, the discrete signal metering method according to an aspect of the present invention comprises the steps of (a) setting the measuring range of the metering Out Fit (MOF) secondary output signal according to the type of hardware, (b) multiplying the MOF secondary output signal value within the set measurement range by a predetermined magnification for each DC / AC, and calculating an amplification ratio (c) using the set measurement range and the calculated amplification ratio. Calculating an automatic amplification ratio and outputting the calculated automatic amplification ratio; (d) when the input signal is equal to or less than a predetermined reference value when converting the continuous signal into a discrete signal, Amplifying the magnitude of an input signal, and (e) attenuating a measurement magnitude interval converted into the discrete signal and outputted at a ratio of the automatic amplification ratio.

In one aspect of the present invention, step (a) is set to have a margin of a predetermined range in consideration of the measurement range of the set MOF secondary output signal.

In addition, in one aspect of the present invention, the step (c) divides the automatic amplification ratio by dividing the maximum value of the measurement range of the MOF secondary output signal by the amplification ratio value using a two-terminal division function. Calculate.

In addition, in one aspect of the present invention, the step (c) includes the step of setting the number of digits of the finite number of the value of the calculated automatic amplification ratio.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features and advantages of the present invention will be more apparent from the following detailed description taken in conjunction with the accompanying drawings, in which: FIG.

The present invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. It is provided to fully inform the owner of the scope of the invention.

According to one of the problem solving means of the discrete signal metering method and apparatus of the present invention described above, when converting a continuous signal into a discrete signal, by measuring the interval of the measurement size automatically according to the signal size, This is possible.

In addition, low hardware resolution can reduce weighing errors.

It is also integrated into existing power meters and protection relays, allowing high-precision discrete signals to be measured at low cost.

In addition, the fast Fourier series (FFT) conversion, there is an advantage that can suppress the increase in memory capacity due to the resolution for each order.

1 is a schematic diagram illustrating a power receiving facility.
2 is a graph of power measurement for each time zone of the power receiving meter and the power generation meter.
3 is a graph showing the precision of a discrete signal.
4 is a block diagram illustrating a discrete signal metering apparatus according to an embodiment of the present invention.
5 is a flowchart illustrating a discrete signal metering method according to an embodiment of the present invention.

The present invention may be variously modified and have various embodiments, and specific embodiments will be illustrated in the drawings and described in detail with reference to the accompanying drawings.

It should be understood, however, that the invention is not intended to be limited to the particular embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

For reference, in the specification, when a part is 'connected' to another part, it is not only 'directly connected' but also 'electrically connected' with another element in between. Also includes.

In addition, when a part is said to "include" a certain component, it means that it may include other components, not to exclude other components unless specifically stated otherwise.

Hereinafter, with reference to the accompanying drawings will be described in detail for the practice of the present invention.

1 is a schematic diagram illustrating a power receiving facility.

The customer's power receiving facility is largely divided into a power receiving facility and a power generation facility, and the power generation facility includes an instrument current transformer 11, a metering device 12, a transformer 13, a power receiving load 14, and a power generation facility 15. It includes.

In addition, the meter may further include a power receiving meter and a power generation meter to measure the received power and the generated power.

In addition, the instrument transformer (Metering Out Fit, hereinafter referred to as MOF) includes an instrument transformer (PT) and an instrument current transformer (CT) therein, and the magnification of the MOF includes a voltage ratio (PT ratio) and a current ratio (CT ratio). Is determined.

2 is a graph of power measurement for each time zone of the power receiving meter and the power generation meter.

The graph shown in FIG. 2 is an example for explaining a measurement error when a load is changed, and is a result of measuring active power for each time measured by a power meter and a power meter of a photovoltaic customer.

The power meter measures the power generation from 6 to 17:00 during the day, while the power meter measures the loss of the transformer when the power is not generated from 17:00 to 6 pm at night.

As shown in FIG. 2, the measured power of the faucet meter is less than 3.5 Kw and the generated power is 950 kW.

The problem is that the MOF ratio is set by the capacity of the transformer or by the contracted power, so when receiving unpowered meters the metering error occurs at no load or light load due to the resolution of the fixed hardware.

3 is a graph showing the precision of a discrete signal.

As shown in Fig. 3, the high precision power meter has a good decomposition performance and a high sampling number.

That is, when the interval 33 of the measurement size is small and the interval 34 of the measurement time is small, the accuracy is high.

However, all the conventional measuring devices have a fixed resolution and sampling capability of the hardware, and when a high precision measurement is required, it is replaced with high precision hardware.

In addition, in order to reduce the measurement size and time interval of the high-precision measuring device, the performance of the weighing device must be good and a large storage memory is required.

In particular, when converting to a fast Fourier type (FFT) signal, since the signal must be resolved for each order, the memory capacity increases rapidly with the signal order.

In this case, it is possible to measure high-precision discrete signals with optimal hardware performance by automatically adjusting the intervals of measurement magnitudes.

Accordingly, the present invention, by automatically adjusting the interval of the measurement size in accordance with the fluctuation of the signal, it is possible to significantly reduce the weighing error compared to the conventional by using the device of the same resolution performance.

4 is a block diagram illustrating a discrete signal metering apparatus according to an embodiment of the present invention.

For reference, the discrete signal metering apparatus shown in FIG. 4 may be embedded in existing electricity meters and protection relays.

Discrete signal metering apparatus 100 according to an embodiment of the present invention is the input unit 110, MOF secondary output signal unit 120, MOF secondary output signal measurement range setting unit 130, A / D conversion unit ( 140, an amplification ratio calculating unit 150, an automatic amplifying unit 160, an input magnification adjusting unit 170, an output magnification adjusting unit 180, and a power calculating unit 190.

Here, the A / D converter 140 may include a measurement size interval setting unit 141 and a hardware resolution capability unit 142.

In describing each component, the input unit 110 inputs necessary information such as a weighing method and a weighing type necessary for weighing information.

The MOF secondary output signal unit 120 determines and outputs the MOF secondary output signal (ie, voltage and current) based on the PT ratio and the CT ratio based on the information input through the input unit 110.

Typically the PT secondary voltage is 110V and the CT secondary current is 5A.

Meanwhile, the MOF secondary output signal measurement range setting unit 130 sets a measurement range of the MOF secondary output signal (hereinafter referred to as a “secondary signal measurement range”) according to the type of hardware, and according to the load characteristics. It can be set to have 1 to 100 times margin considering the secondary signal measurement range of changing hardware.

For reference, CT secondary current is 5A in normal state, but in case of failure, overcurrents of several times more than normal current occur, so the measurement range of discrete signal is generally 2 ~ 5 times in case of meter and protection relay. Designing a margin of hardware of 20 to 50 times allows short-circuit current measurements.

Therefore, the margin of the MOF secondary output signal measurement range setting unit 130 is not limited to the above values, and may be designed by applying various margins according to an embodiment.

Meanwhile, the A / D converter 140 converts the continuous signal into a discrete signal, and includes a measurement size interval setting unit 141 and a hardware resolution capability unit 142.

Here, the measurement size interval setting unit 141 divides the resolution capability of the hardware from the maximum value of the secondary signal measurement range set by the MOF secondary output signal measurement range setting unit 130 by using a 2-terminal division function. The measurement size interval can be calculated.

On the other hand, the hardware resolution capability section 142 of the A / D conversion section 140 calculates the resolution resolution of the hardware.

For example, the resolution of the hardware depends on the hardware's bits (bits), such as 2 ¹⁰ = 1024, 2 ¹² = 4096, 2 ¹⁴ = 16384, and for expensive products, the measurement intervals are narrow.

On the other hand, the amplification ratio calculation unit 150 is a predetermined magnification for each of the MOF secondary output signal value and the direct current (DC) / AC (AC) within the secondary signal measurement range set by the MOF secondary output signal measurement range setting unit 130 Calculate the amplification ratio (比) using and output it.

That is, the amplification ratio can be calculated by multiplying the MOF secondary output signal value within the secondary signal measurement range by a predetermined magnification for each DC / AC, and calculating the DC / AC. For example, the predetermined magnification may be set to 2 for the AC signal and 1 for the DC signal.

For example, the amplification ratio calculator 150 may set the setting range of the amplification ratio to 1 to 100 times, and may be set to 2 to 5 times for the wattmeter and 20 to 50 times for the protection relay.

In addition, the amplification ratio calculator 150 may recalculate the calculated amplification ratio according to the sampled time, and the sampled time may be set to 0 to 1000 ms.

On the other hand, the automatic amplification unit 160 calculates the amplification ratio by using a two-terminal division function for the maximum value of the secondary signal measuring range according to the type of hardware set by the MOF secondary output signal measuring range setting unit 130. By dividing by the amplification ratio value calculated in the unit 150, it is possible to calculate the automatic amplification ratio according to the load, and output a signal for the calculated automatic amplification ratio.

In addition, the automatic amplification unit 160 may determine the number of digits of the finite number with respect to the value of the automatic amplification ratio, the metering device for measuring the load current in the steady state measures the number of digits from 0 to 1, the fault current in the transient state The metering device can be set to 1 to 3 digits.

For reference, the maximum value of the secondary signal measurement range according to the type of hardware and the amplification ratio value calculated by the amplification ratio calculator 150 may be represented by a root mean square (RMS).

Meanwhile, if the signal input to the A / D converter 140 is equal to or less than a predetermined reference value, the input magnification adjusting unit 170 may adjust the A / D converter based on the automatic amplification ratio output from the automatic amplifier 160. 140 amplifies the magnitude of the input signal.

In addition, the output magnification adjusting unit 180 may correct the weighing error by attenuating the output value (measurement size interval) output from the A / D converter 140 by the automatic amplification ratio output from the automatic amplifying unit 160. have.

For reference, the discrete signal metering apparatus 100 of the present invention may configure various types of systems according to the amplification ratio output from the automatic amplifier 160.

For example, the input magnification adjusting unit 170 divides the measurement section into three equal parts into 1 to 1000 times no-load measurement section, 0.1 to 100 times load current measurement section, and 0.01 to 10 times fault current measurement section according to the resistance magnification. It may be.

Meanwhile, the power calculator 190 may calculate the active power and the reactive power by using the discrete signal output from the output magnification adjusting unit 180, and output the same through a display device (not shown).

For reference, the conventional measurement size interval calculation method is described. In the conventional measurement size interval calculation method, the measurement size interval is fixed by the resolution capability of the hardware.

Therefore, since the measurement interval is constant regardless of the magnitude of the MOF secondary output signal, weighing error occurs when the signal is relatively out of the measurement range of the hardware, that is, at no load or light load, compared to the normal load signal. There was.

In particular, power generation customers need to meter power and power separately, so the power meter only measures the loss of transformers or on-site power. Therefore, there is a need for a method for improving errors at no load or light load.

For example, assuming that a 1000 kW photovoltaic customer has a PT ratio of 13200 / 110V, a CT ratio of 30 / 5A, and a hardware resolution of the weighing device is 12 bits, the error between the generation load and the faucet load at no load is shown. Can be calculated

If the instantaneous power of the power generation meter is 950kW during solar power generation from 6 o'clock to 17 o'clock, it is 950 / (22.9 * 1.732 * 0.9) = 26.6A, and 26.6 * 5/30 = 4.43A continuous signal is output.

In general, since the CT secondary rated current is 5A, the measurement range of the discrete signal is 5A * 1.2 = 6A for the instantaneous maximum value, and the alternating current alternates between + 6A and -6A, which is twice the measurement range of DC voltage. Is generated.

In addition, the hardware measurement range for discrete signals is 6 * 2 times (AC) * 2 times (freedom) = 24A, and the measurement size interval is measured at intervals of 24 / (212) = 5.85mA, so 5.85mA Measurements less than 22.9 * 1.732 * 0.9 = 209W cannot be measured, and the measurement error is (5.85mA * 100) /4.43A=0.132%, which is good under 1.0%.

However, when the unpowered faucet meter only measures the loss of the transformer when it is undeveloped from 17 o'clock to 6 o'clock, the measurement error is calculated as follows.

In other words, 3.5 kW of transformer loss of a power receiving meter is converted into current, and 3.5 / (22.9 * 1.732 * 0.9) = 0.098A, and 0.098 * 5/30 = 16.3mA when converted to secondary current.

Therefore, there is a problem that the measurement error of transformer loss at no load becomes (5.85mA * 100) /16.3mA = 35.88%, which is out of the specified value.

Accordingly, in the present invention, in order to solve the above-mentioned problems (errors in measurement size intervals), the input magnification adjusting unit 170 and the A / D for adjusting the magnification of the input resistance of the A / D converter 140 are provided. Through the output magnification adjusting unit 180 that adjusts the output magnification of the converter 140, the interval of the measurement size may be automatically adjusted according to the magnitude of the MOF secondary output signal.

On the other hand, as shown in Figure 2, when the MOF secondary CT current for the loss power 3.5kW of the transformer at no load is 0.098A, the interval of the measurement size using the conventional method as described above, and the present invention described above If you compare the result of calculating the interval of the measurement size according to

[Equation 1]

?

(Hardware maximum measurement size (i.e., maximum value of secondary signal measurement range) 24A = 5 × 1.2 × 2 (AC) × 2 times, hardware resolution = 2 ¹² )

&Quot; (2) "

(Hardware maximum measurement size (i.e., maximum value of secondary signal measurement range) 24A = 5 × 1.2 × 2 (AC) × 2 times, hardware resolution = 2 ¹² , auto amplification ratio = 24 / (16.3mA × 1.2 × 2 × 4) = 153

That is, the output magnification adjusting unit 180 of the present invention attenuates and weighs the amplification ratio 153 output from the automatic amplifying unit 160 with respect to the interval of the measurement size, which is an output value output from the A / D converter 140. The error can be corrected.

As a result, it can be seen that the conventional measurement of discrete signals at 5.85 mA and 209 W intervals can be measured at 0.038 mA and 1.36 W intervals according to the present invention.

5 is a flowchart illustrating a discrete signal metering method according to an embodiment of the present invention.

For reference, the discrete signal metering method illustrated in FIG. 5 may be performed by the discrete signal metering apparatus 100 illustrated in FIG. 4.

First, the discrete signal metering apparatus 100 sets the measurement range of the MOF secondary output signal according to the type of hardware (S501).

Here, the discrete signal metering apparatus 100 may be set to have a margin of a predetermined range in consideration of the measurement range of the set MOF secondary output signal.

After step S501, the discrete signal metering apparatus 100 calculates an amplification ratio by multiplying the MOF secondary output signal value within the measurement range set in step S501 by a predetermined magnification for each DC / AC (S502).

After step S502, the discrete signal metering apparatus 100 calculates the automatic amplification ratio using the measurement range of the MOF secondary output signal set in step S501 and the amplification ratio calculated in step S502, and outputs the calculated automatic amplification ratio. (S503).

At this time, the discrete signal metering apparatus 100 may calculate the automatic amplification ratio by dividing the maximum value of the measurement range of the MOF secondary output signal by the amplification ratio value using a two-terminal division function.

In addition, the discrete signal metering apparatus 100 may set a finite number of digits for the calculated automatic amplification ratio.

After step S503, the discrete signal metering device 100 amplifies the magnitude of the input signal based on the automatic amplification ratio output in step S503 when the input signal is equal to or less than a predetermined reference value when converting the continuous signal into a discrete signal ( S504).

However, after step S504, the discrete signal metering device 100 attenuates the measurement magnitude interval which is converted into the discrete signal and outputted at the ratio of the automatic amplification ratio output in step S503 (S505).

The foregoing description is merely illustrative of the technical idea of the present invention, and various changes and modifications may be made by those skilled in the art without departing from the essential characteristics of the present invention.

Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments.

The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

100: discrete signal metering device of the present invention
110: input unit
120: MOF secondary output signal unit
130: MOF secondary output signal measurement range setting unit
140: A / D converter
150: amplification ratio calculation unit
160: automatic amplifier
170: input scaling unit
180: output scaling unit
190: power calculation unit

Claims (13)

In the discrete signal metering device,
MOF secondary output signal measurement range setting section for setting the measurement range of the metering out fit (MOF) secondary output signal according to the type of hardware,
For each MOF secondary output signal value and DC / AC in the set measurement range
An amplification ratio calculator for calculating an amplification ratio using a predetermined magnification,
An automatic amplification unit for calculating an automatic amplification ratio using the set measurement range and the calculated amplification ratio and outputting the calculated automatic amplification ratio;
An input magnification adjusting unit that amplifies the magnitude of the input signal based on the output automatic amplification ratio when the input signal input to the A / D converter converting the continuous signal into a discrete signal is equal to or less than a predetermined reference value;
An output magnification adjusting unit that adjusts an interval of a measurement size output from the A / D converter based on the output automatic amplification ratio within the set automatic amplification range.
Discrete signal metering apparatus comprising a.
The method of claim 1,
The MOF secondary output signal measuring range setting unit sets the signal having a margin of a predetermined range in consideration of the measurement range of the set MOF secondary output signal.
The method of claim 1,
The amplification ratio calculating unit sets the amplification ratio up to 5 times in the case of a power meter, up to 50 times in the case of a protective relay.
The method of claim 1,
The amplification ratio calculator calculates the amplification ratio by multiplying the MOF secondary output signal value by a predetermined magnification for each DC / AC, but the predetermined magnification for each DC / AC is 1 for DC and 2 for AC. Discrete signal metering device.
The method of claim 4, wherein
The amplification ratio calculating unit recalculates the calculated amplification ratio according to a sampled time.
The method of claim 1,
The automatic amplifying unit outputs a signal of the automatic amplification ratio according to the load by dividing the maximum value of the measurement range of the secondary output signal by the amplification ratio using a two-terminal division function.
The method of claim 1,
And the automatic amplifying unit sets a digit of a finite number of digits with respect to the value of the output automatic amplification ratio.
The method of claim 7, wherein
The automatic amplifying unit may be configured to measure the load current in a steady state to a maximum number of digits of the finite number of points, and to set a number of digits of the finite number of points to a minimum of one and a maximum of three. Discrete signal metering device.
The method of claim 1,
The output magnification adjusting unit attenuates the output measurement magnitude interval at a ratio of the automatic amplification ratio to correct an error with respect to the measurement magnitude interval. In the discrete signal metering method,
(a) setting the measurement range of the metering out fit (MOF) secondary output signal according to the type of hardware;
(b) calculating an amplification ratio by multiplying a MOF secondary output signal value within the set measurement range by a predetermined magnification for each DC / AC;
(c) calculating an automatic amplification ratio using the set measurement range and the calculated amplification ratio, and outputting the calculated automatic amplification ratio;
(d) amplifying the magnitude of the input signal based on the output automatic amplification ratio when the input signal is equal to or less than a predetermined reference value when converting the continuous signal into a discrete signal; and
(e) attenuating a measurement magnitude interval converted into the discrete signal and outputted at a ratio of the automatic amplification ratio;
A discrete signal metering method comprising a.
11. The method of claim 10,
The step (a) is set to have a margin of a predetermined range in consideration of the measurement range of the set MOF secondary output signal, discrete signal metering method.
11. The method of claim 10,
In the step (c), the automatic amplification ratio is calculated by dividing the maximum value of the measurement range of the MOF secondary output signal by the amplification ratio value using a two-terminal division function.
The method of claim 12,
Step (c) is a step of setting the number of digits of the finite number of the calculated value of the automatic amplification ratio
A discrete signal metering method comprising a.

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