WO2017146311A1

WO2017146311A1 - Evaluation device of voltage transformer comparator

Info

Publication number: WO2017146311A1
Application number: PCT/KR2016/006317
Authority: WO
Inventors: 정재갑; 김규태
Original assignee: 한국표준과학연구원
Priority date: 2016-02-23
Filing date: 2016-06-14
Publication date: 2017-08-31
Also published as: KR20170099466A; KR101851968B1

Abstract

The present invention relates to an evaluation circuit. The evaluation circuit of the present invention comprises: a ratio error evaluation circuit for measuring a ratio error of a voltage transformer comparator; a phase error evaluation circuit for measuring a phase error of the voltage transformer comparator; and a switch for connecting one of the ratio error evaluation circuit and the phase error evaluation circuit to the voltage transformer comparator, wherein the phase error evaluation circuit consists of a series circuit of a variable resistor and a fixed resistor and the ratio error evaluation circuit consists of a series circuit of a variable resistor and a capacitor.

Description

[Calibration according to Rule 26, 19.07.2016] Evaluation device of voltage transformer comparator

The present invention relates to a measuring apparatus, and relates to an evaluation apparatus for a voltage transformer comparator.

A voltage transformer (VT) is commonly used in the power industry for high voltage and power loss measurements. These voltage transformers convert high voltage to low voltage for safe and precise measurement of high voltage.

In the voltage transformer, the secondary side voltage is connected to the measuring device such as the voltmeter and the watt hour meter and the protection relay, and is used for the power quality verification and the power amount measurement. Therefore, the secondary side voltage of the voltage converter must match the primary side voltage with the correct conversion ratio. There should also be no displacement.

A voltage transformer test set (VTTS) (or a voltage transformer test set) is used to measure the ratio error and phase error of the voltage transformer. That is, the voltage transformer comparator compares the secondary voltage of the measured voltage transformer with the secondary voltage of the standard voltage transformer, and measures the error and phase error of the measured voltage transformer.

Conventional voltage transformer comparators have complex structures, volumes, and weights for evaluation instruments for evaluating ratio and phase errors. Therefore, there is a problem that the evaluation device for evaluating the conventional voltage transformer comparator is moved, and the voltage transformer comparator can not be evaluated.

It is an object of the present invention to provide an apparatus for evaluating a movable voltage transformer comparator.

The apparatus for evaluating a voltage transformer comparator according to the present invention includes a ratio error evaluation circuit for measuring a bias error of a voltage transformer comparator, a phase error evaluation circuit for measuring a phase error of the voltage transformer comparator, And a switch for connecting one of the error evaluation circuit and the phase error evaluation circuit.

In this embodiment, the error-rate evaluation circuit includes a power supply unit for supplying power, a variable resistor having one end connected to the power supply unit and having a variable resistance, and one end connected to the variable resistor, And a fixed resistor whose one end is connected to the contact.

In this embodiment, the switch unit may include a first switch for connecting one end of a first resistor of the voltage transformer comparator to the power supply unit and a ground terminal of the variable resistor, a second switch for connecting one end of the first resistor to the variable resistor And a third switch for connecting one end of a second resistor of the voltage transformer comparator to a contact of the variable resistor and the fixed resistor, and a second switch for connecting the other end of the first resistor to the contact of the fixed resistor, And a fourth switch for connecting a contact of another end of the two resistors to a contact between the fixed resistor and the ground terminal.

In this embodiment, the third switch is turned off while the second switch is turned on to measure the offset of the error, and the second switch is turned off while the third switch is turned on.

In this embodiment, the first resistor is a primary resistor connected to the standard voltage transformer and the second resistor is a secondary resistor connected to the voltage transformer for testing in a bias error measurement according to negative polarity.

In this embodiment, the first resistor is a secondary resistance connected to the voltage transformer for testing, and the second resistor is a primary resistance connected to the standard voltage transformer in the measurement of the error according to the positive polarity.

In this embodiment, to calibrate the bias error, the variable resistor is adjusted to a resistance of 0.01 ohms to 200 ohms, and the fixed resistor has a resistance of 2 kilo ohms.

In this embodiment, the phase error evaluating circuit includes a power supply unit for supplying power, a variable resistor having one end connected to the power supply unit and having a variable resistance, and one end connected to the variable resistor, And a capacitor whose one end is connected to the contact.

In this embodiment, the switch unit may include a first switch for connecting one end of a first resistor of the voltage transformer comparator to the power supply unit and a ground terminal of the variable resistor, a second switch for connecting one end of the first resistor to the variable resistor A second switch connected to the contact of the capacitor, a third switch for connecting one end of a second resistor of the voltage transformer comparator to the contact of the variable resistor and the capacitor, and a third switch for connecting the other end of the first resistor and the second resistor And a fourth switch for connecting the other end of the contact to the contact between the capacitor and the ground terminal.

In this embodiment, for the calibration of the error, the variable resistor is adjusted to a resistance from 0.01 ohms to 200 ohms, and the capacitor has a capacitance of 2 uF.

The evaluation apparatus of the present invention can be implemented to be movable for evaluation of a voltage transformer comparator by having a simple structure implemented by a series connection of a variable resistor and a fixed resistor or a series connection of a variable resistor and a capacitor.

1 is an exemplary illustration of a voltage transformer comparator in accordance with the present invention,

2 is a diagram illustrating an exemplary evaluation device of a voltage transformer comparator according to the present invention,

3 is a diagram exemplarily showing a ratio error evaluation circuit of an evaluation apparatus according to the present invention,

4 is a diagram exemplarily showing a phase error evaluation circuit of an evaluation apparatus according to the present invention,

5 is a diagram illustrating a phase according to the phase error measurement according to the present invention,

Figure 6 is an exemplary illustration of the evaluation of the error error offset of an evaluation device according to the present invention;

FIG. 7 is an exemplary illustration of a bias error evaluation corresponding to a calibration point for a negative polarity of an evaluation device according to the present invention;

8 is an exemplary illustration of evaluation of the phase error offset of an evaluation device according to the present invention,

9 is an exemplary illustration of a phase error evaluation corresponding to a calibration point for the negative nature of the evaluation device according to the invention,

FIG. 10 is a diagram illustrating exemplary calibration of error error according to the present invention, and FIG.

11 is a diagram illustrating an exemplary phase error calibration according to the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing the best mode for carrying out the present invention. Fig.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, only parts necessary for understanding the operation according to the present invention will be described, and descriptions of other parts will be omitted in order to avoid obscuring the gist of the present invention.

The present invention provides an evaluation device implemented to be movable to evaluate a voltage transformer test set (VTTS). The evaluation apparatus of the present invention can be used for evaluating a voltage transformer comparator (VTTS) (or a voltage transformer test set) used for evaluating a ratio error and a phase error of a voltage transformer (VT) It is equipment used for. Therefore, the evaluation apparatus performs the evaluation operation of the error and phase error of the voltage transformer comparator according to the calibration of the error and phase error.

Figure 1 is an exemplary illustration of a voltage transformer comparator.

Referring to FIG. 1, there is shown a power quality and power amount evaluation using a voltage transformer 20 in a voltage transformer comparator 10.

In the voltage transformer 20, a standard voltage transformer (STD) is placed on the primary side, and a test device TEST (e.g., voltmeter, watt hour meter) for evaluation is connected to the secondary side. The voltage transformer 20 includes a power supply unit 21 capable of outputting a high voltage (HV). One end of the standard voltage transformer STD is connected to the power source unit 21 and the other end of the standard voltage transformer STD is connected to the other end of the power source unit 21 through a contact with the test device TEST.

The voltage transformer comparator 10 includes a Burden (B) connected in parallel to the test device TEST. The voltage transformer comparator 10 includes a first resistor Rx connected to the primary side and a second resistor Rn connected to the secondary side. Here, rx and rn represent impedance values. The voltage transformer comparator 10 compares the output voltage between the test device TEST and the standard voltage transformer STD after applying the same excitation voltage to both the test device TEST and the standard voltage transformer STD To determine errors.

The voltage transformer comparator 10 can operate as a current comparator. Can operate on the principle of magnetic flux created by the magnetomotive force exerted on the magnetic cores of two windows (with respect to each of rx and rn sides) of opposite polarity. The magnetic flux is canceled, and the current comparator is balanced.

The input impedances rx, rn may have a relatively large value. At this time, the voltage transformer 20 calculates the error ratio

) And phase error (

).

Here, kn is the ratio of the denaturation ratio, Up is the actual main voltage of the test device TEST, and Us is the actual secondary voltage.

Is a mains voltage phasor,

Is a secondary voltage phasor.

Assuming that the voltage is applied as the main voltage to both the test device TEST and the standard voltage transformer STD and that there is no error in the standard voltage transformer STD, the errors in the single modulation ratio are related only to the secondary voltage. Therefore, the error of the voltage comparator comparator 10 can be expressed by the following equation (2).

Where U _X is the secondary voltage of the test device TEST and U _N is the secondary voltage of the standard voltage transformer STD.

Is the secondary voltage phase of the test device TEST,

Is the secondary voltage phase of the standard voltage transformer (STD).

Represents the ratio between the secondary voltages of the test device TEST and the standard voltage transformer STD.

Represents the difference between the secondary voltage phases of the test device TEST and the standard voltage transformer STD.

2 is a diagram illustrating an exemplary evaluation apparatus of a voltage transformer comparator according to the present invention.

Referring to FIG. 2, the evaluation apparatus 100 includes a ratio error evaluation circuit 110, a phase error evaluation circuit 120, and a switch unit 130.

The error error evaluation circuit 110, when connected to the voltage transformer comparator 10 via the switch unit 130, performs a calibration operation for evaluation of error error. The error ratio evaluation circuit 110 includes a first node N1 to a third node N3 for connection to the voltage comparator comparator 10. [ For example, the error ratio evaluation circuit 120 is constituted by a series circuit of a variable resistor and a fixed resistor. The phase error evaluating circuit 120 performs a calibration operation for measuring the phase error when the voltage comparator 10 is connected to the comparator 10 via the switch unit 130. The phase error evaluation circuit 120 includes fourth to sixth nodes N4 to N6 for connection to the voltage comparator comparator 10. [ For example, the phase error evaluation circuit 120 is constituted by a series circuit of a variable resistor and a capacitor.

The switch unit 130 includes the first switch SW3 to the eighth switch SW8. The first switch SW1 is turned on or off between the first measuring node N1 and the first node 11 connected to the second resistor Rn. The second switch SW2 is turned on or off between the second measurement node N2 and the first node 11. [ The third switch SW3 is turned on or off between the second measuring node N2 and the second node N12 connected to the first resistor Rx. The fourth switch SW4 is turned on or off between the third measuring node N3 and the third node N13 connected to the node between the first resistor Rx and the second resistor Rn.

Thus, the fifth switch SW5 is turned on or off between the fourth measuring node N4 and the first node N11, the sixth switch SW6 is turned on or off between the fifth measuring node N5 and the first node N11, Lt; RTI ID = 0.0 > N11. &Lt; / RTI > The seventh switch SW7 is turned on or off between the fifth measuring node N5 and the second node N12. The eighth switch SW8 is turned on or off between the sixth measuring node N6 and the third node N13.

And the error of the voltage comparator comparator 10 is measured by the ON operation of the first switch SW1 to the fourth switch SW4. At this time, only one of the first switch SW1 and the second switch SW2 is selectively turned on. That is, when the first switch SW1 is turned on, the second switch SW2 is turned off, and when the second switch SW2 is turned on, the first switch SW1 is turned off. The phase error of the voltage-shifter comparator 10 is measured by the ON operation of the fifth switch SW5 and the eighth switch SW8. Again, only one of the fifth switch SW5 and the sixth switch SW6, such as the first switch SW1 and the second switch SW2, is selectively turned on.

In the above, the evaluation apparatus 100 shows the error and phase error measurement according to the negative polarity, and the error and phase error according to the positive polarity change the positions of the first resistor Rx and the second resistor Rn Can be measured through a combined node.

The operation of the first switch SW1 through the eighth switches SW8 included in the switch unit 130 may be controlled by a user control signal generated by a user control or a switch generated through a separate control unit And can be controlled by a control signal or the like.

On the other hand, the voltage transformer comparator 10 can measure the voltage components of the two inputs (U _X , U _N ) at the same ground point. In addition, the voltage level of U _X is provided by the term of the voltage level of U _N in phase with quadrature.

3 is a diagram exemplarily showing a ratio error evaluation circuit of an evaluation apparatus according to the present invention.

3, the error-ratio evaluation circuit 110 includes a power supply unit 111, a first variable resistor Rv1, and a fixed resistor R. [ The first switch SW1 of the switch unit 130 is turned on to connect the first measurement node N1 to the first node N11 and the third switch SW3 is turned on to connect the second measurement node N2 ) To the second node N12, and the fourth switch SW4 is turned on to connect the third measurement node N3 and the third node N13. At this time, the second switch SW2 is turned off.

The first variable resistor Rv1 is connected at one end to the power supply unit 111 and at the other end to the fixed resistor R. [ One end of the fixed resistor R is connected to the first variable resistor Rv1 and the other end is connected to the contact point between the power supply part 111 and the ground terminal. Thereby, the first variable resistor Rv1 and the fixed resistor R are serially connected for the estimation of the error. Resistors including the function of a voltage divider are considered as inductors and resistors connected in series, but commercially available non-inductive resistors can be used. Accordingly, the error-error evaluation circuit 110 may have the function of a resistance voltage divider.

At this time, the voltages applied to the input voltages U _N and U _X in the voltage transformer comparator 10 are the same for a voltage drop across the input resistance of the voltage transformer comparator 10.

The voltage at point U _X decreases at the ratio of (R _V + Z _X ) / Z _{X at} the point U _N. RV is the actual resistance (resistance value) of the first variable resistor Rv1. The resistance of the first variable resistor Rv1 changes for calibration for the measurement of the bias error. Z _X is the actual impedance value of the fixed resistor R connected in parallel to the input impedance rx, and the error error can be theoretically expressed by the following equation (3).

Equation (3) shows the error in the region of the negative polarity.

In the positive polarity region, the connection between the nodes of U _X and U _N can be obtained by exchanging. In this case, the error in the positive polarity can be expressed theoretically as shown in the following equation (4).

Where Z _N is the actual impedance value of the fixed resistor R connected in parallel to the input impedance rn. Therefore, by the resistance change of the first variable resistor Rv1, the theoretical error for the calibration point is measured in the negative and positive polarities.

4 is a diagram exemplarily showing a phase error evaluation circuit of an evaluation apparatus according to the present invention.

Referring to FIG. 4, the phase error evaluation circuit 120 includes a power supply unit 121, a second variable resistor Rv2, and a capacitor C. The fifth switch SW5 of the switch unit 130 is turned on to connect the fourth measurement node N4 to the first node N11 and the seventh switch SW5 is turned on to connect the fifth measurement node N5 ) To the second node N12, and the eighth switch SW8 is turned on to connect the sixth measuring node N6 and the third node N13. At this time, the sixth switch SW6 is turned off.

The second variable resistor Rv2 has one end connected to the power supply unit 121 and the other end connected to the capacitor C. [ One end of the capacitor C is connected to the second variable resistor Rv2 and the other end is connected to the contact between the power supply 121 and the ground terminal. Thereby, the second variable resistor Rv2 and the capacitor C are connected in series for phase error evaluation. A non-inductive resistor and a dissipation capacitor with a value less than 1 x 10 ^< ^-3 > may be used. Thus, the phase error estimating circuit 120 may have the function of a quadrature RC divider.

The evaluation of the phase error of the voltage-shifting comparator 10 is based on the phase difference between the terminals formed with U _X and U _N.

At this time, the phase error of the voltage comparator comparator 10 can be expressed as shown in FIG. 5 below. The lower part of the voltage divider can be regarded as an even serial circuit.

5 is a diagram illustrating a phase according to the phase error measurement according to the present invention.

Referring to FIG. 5, (a) schematically illustrates a phase error evaluation circuit 120 implemented with a resistor-capacitor voltage divider. The second variable resistor Rv2 and the capacitance Cc of the capacitor C are connected in series. Here, the first resistor Rx, one end of which is connected to the contact between the second variable resistor Rv2 and the capacitor C, and the other end of which is connected to the ground terminal, is connected in parallel to the capacitor C. The voltage U _N applied to the resistor Rv and the voltage U _X applied in the capacitance direction are shown.

(b) shows a series circuit equivalent to (a). The second variable resistor Rv2 is connected to a resistor Rxeq having a resistance of rxeq at the other end to which a voltage UN is applied at one end. The resistor Rxeq is connected at one end to a second variable resistor Rv2 and at the other end to a capacitor Cceq having a capacitance Xceq. The voltage U _X is applied to the resistor Rxeq through the contact point with the second variable resistor Rv2.

the resistor Rx and the capacitor C connected in parallel in FIG. 5A may be an equivalent circuit to a parallel circuit of a resistor Rxeq and a capacitor Cceq connected in series.

(b), the resistance rxeq and the capacitance Xceq can be expressed by the following Equation (5).

(c). The vertical axis represents the capacitance Xceq, and the horizontal axis represents rxeq + Rv. At this time, the points (U _X , U _N ) where the voltages are applied are shown. At this time, the phase error value can be expressed by the following Equation (6).

Equation (7) below represents the phase error value according to the negative polarity.

Equation (8) represents a resistance (rneq) and a capacitance (Xceq) according to a phase error value.

6 is a diagram illustrating an exemplary evaluation of the error error offset of the evaluation apparatus according to the present invention.

Referring to FIG. 6, the calibration for the error error evaluation is made in two steps. An evaluation device (100) for evaluating the offset of the error is connected to a voltage transformer comparator (10). To this end, the second switch SW2 to the fourth switch SW4 are turned on. Thereby, the second measuring node N2 is connected to the first node N11 and the second node N12, and the third measuring node N3 is connected to the third node N13.

The offset values caused by both the input impedances (rx and rn) and possible impedances are evaluated. (First node N11 and second node N12) outputting the same voltage of U _X and U _N are connected with the same potential, the voltage comparator comparator 10 detects the zero value of the error do. However, the evaluation apparatus 100 may detect a non-zero value due to a difference in input impedance of the voltage transformer comparator 10.

The next step will be described with reference to Fig. 7 below.

Fig. 7 is an exemplary diagram illustrating a non-error evaluation corresponding to a calibration point for a negative polarity of an evaluation apparatus according to the present invention.

Referring to Fig. 7, the first switch SW1, the third switch SW3, and the fourth switch SW4 are turned on. Thereby, the first measurement node N1 is connected to the first node N11, the second measurement node N2 is connected to the second node N12, the third measurement node N3 is connected to the third node N12, (N13).

At this time, the calibration can be performed by varying the value of the first variable resistor Rv1. Thus, the measured error value can be measured by subtracting the measured error value in FIG. 6 from the error value.

As in the case of the negative polarity error measurement described with reference to FIGS. 6 and 7, U _X and U _N may be changed and connected to the evaluation apparatus 100 to measure the error with respect to the positive polarity.

At this time, the first variable resistor Rv1 is about 0.01

About 200

And the fixed resistor R can be adjusted to a value in the range of about 2 kilo ohms (k

).

8 is an exemplary diagram illustrating evaluation of the phase error offset of the evaluation apparatus according to the present invention.

Referring to FIG. 8, calibration for phase error evaluation is performed in two steps, such as a bias error. Lt; RTI ID = 0.0 > 100 < / RTI > and a voltage transformer comparator 10 for evaluating the offset of the phase error.

An evaluation device (100) for evaluating the offset of the phase error and a voltage transformer comparator (10) are connected. To this end, the sixth switch SW6 to the eighth switch SW8 are turned on. Thus, the fifth measuring node N4 is connected to the first node N11 and the second node N12, and the sixth measuring node N3 is connected to the third node N13. (First node N11 and second node N12) outputting the same voltage of U _X and U _N are connected at the same potential so that a zero value of the phase error is detected in the voltage transformer comparator 10 do. However, the evaluation apparatus 100 may detect a non-zero value due to a difference in input impedance of the voltage transformer comparator 10.

FIG. 9 is an exemplary diagram illustrating a phase error evaluation corresponding to a calibration point for a negative characteristic of an evaluation apparatus according to the present invention.

Referring to Fig. 9, the fifth switch SW5, the seventh switch SW7, and the eighth switch SW8 are turned on. Thereby, the fourth measuring node N4 is connected to the first node N11, the fifth measuring node N5 is connected to the second node N12, the sixth measuring node N6 is connected to the third node N11, (N13).

At this time, the calibration can be performed by varying the value of the second variable resistor Rv2. Thus, the measured phase error value can be measured by subtracting the phase error value measured in FIG.

A series of quadrature circuits evaluates the phase error. The phase error reading can be performed up to about +/- 14crad by the use of a fixed capacitor having a value of 2 microfarads (uF), and the second variable resistor Rv2 is capable of reading the first variable resistor Rv1 ). &Lt; / RTI > Therefore, the second variable resistor Rv2 is about 0.01

About 200

To < / RTI >

The theoretical value requires the actual values of the input impedances as well as the actual values of the divider resistances and capacitance components, and the input-input-impedance measurement of the amplifier-comparator 10 during the evaluation is very important.

The input impedance rx of the voltage transformer comparator 10 on the X side can be determined by the negative bias error measurement while the first variable resistor Rv1 is changing.

Equation (3) can be expressed as Equation (9) below.

When the error is measured by the function of the resistance of the first variable resistor Rv1, the slope of the optimal straight line for the data follows - (1 / Z _X ). From this measurement of the tilt, the input impedance rx is determined as shown in Equation (10) below.

Similar to the negative bias error measurement, the input impedance rn of the N side of the voltage transformer comparator 10 can be determined by the slope measurement at the positive polarity. At this time, Equation (4) can be expressed as Equation (11) below.

The first time the non-error measurement as a function of the resistance of the variable resistor (Rv1), the slope of the best straight line for the data is to be in accordance with (1 / Z _N). From the measurement of the slope, the input impedance rn is determined as shown in Equation (12) below.

For example, a calibration can be performed by application of 100 volts (V) at 60 Hz (Hz) for measurement of error and phase error in the range of +/- 10% and +/- 14crad. After the offset measurement, 0.037

From 192.502

The error can be measured while the variable resistor Rv, that is, the first variable resistor Rv1, is changed. The slope of the straight line fitted from the data is -0.000576 according to - (1 / ZX) from equation (9)

^-1 . The obtained input impedance (rx) is given by Zx = 1.737.06

And R = 2001.34

Using 13154

.

For example, the calibration results of the bias error in the negative polarity of the voltage transformer comparator are shown in Table 1 below.

The calibration value for the error as a function of the variable resistor Rv, that is, the function of the first variable resistor Rv1, in the negative polarity obtained from the equation (3) is shown in the second row of Table 1. The measurement results for the error are shown with errors. The error represents the absolute value of the difference between the calculated value and the measured value. It can be seen that the overall range in the negative range of the error is less than 10 x 10 ^-6 .

Similar to the negative polarity, the evaluation for the positive polarity is performed in the same way after the exchange between the U _X and U _N inputs. The input impedance rn can be calculated from Equation (11) and Equation (12) by ZN = 1737.94

And R = 2001.34

Using 13205

. &Lt; / RTI >

The calibration value for the error as a function of the variable resistor Rv, i.e., the function of the first variable resistor Rv1, in the negative polarity obtained from the equation (4) is shown in the second row of Table 1. It can be seen that the overall range is less than 10 x 10 ^-6 in the positive range of the error, excluding the calculated error of 11.08%, corresponding to the absolute value error of 0.01%.

After the offset measurement, the phase error is measured by variation of the variable resistor Rv, that is, the second variable resistor Rv2 within the range of 0.044 to 192.510. rx = 13154

, Xc = 1325.6

And Equation 5, xreq and Xceq are 132.23

And 1312.2

Respectively. For example, the calibration result of the phase error in the negative polarity of the voltage transformer is shown in Table 3 below.

The phase error in the negative polarity is calculated by Equation 6 and is shown in the second row of Table 3. [ The measurement results for the phase error are shown with errors. The in-phase errors obtained for the full range of phase values are calculated to be 0.001 crad, excluding the calculated phase error of the phase error of -14.22 crad, corresponding to an absolute value error of 0.02 crad.

Similar to the negative polarity, the evaluation for the positive polarity is performed in the same way after the exchange between the U _X and U _N inputs. rn = 13205

, Xc = 1325.6

And Equation 8, rneq and Xceq are 131.73

And 1312.3

Respectively. The phase error at the positive polarity is calculated by equation (7). For example, the calibration result of the phase error in the negative polarity of the voltage transformer is shown in Table 4 below. It can be seen that the total positive phase error is less than 0.003crad, except that the calculated phase error of 6.56crad and 14.22crad is 0.01crad.

The measurement uncertainty for the investigated error range in the voltage transformer comparator calibration can be shown in Table 5 below. Table 5 lists the sources of uncertainty, composite standard uncertainty and extended uncertainty.

Similar to the bias error, the measurement uncertainty for the investigated phase error range in the voltage transformer comparator calibration can be shown in Table 6 below.

A voltage comparator comparator described in Tables 1 to 6 is referred to as A, and a voltage comparator comparator of another manufacturer is referred to as B.

10 is a diagram illustrating exemplary calibration of error error according to the present invention.

Referring to Fig. 10, the solid line shows the specification of the manufacturer. The vertical axis represents the error within the ratio, and the horizontal axis represents the calculated error.

Referring to Fig. 11, the solid line is a specification of the manufacturer. The vertical axis represents the in-phase error, and the horizontal axis represents the calculated phase error.

Accordingly, the evaluation apparatus according to the present invention can be implemented to be movable for evaluation of a voltage transformer comparator by having a simple structure implemented by a series connection of a variable resistor and a fixed resistor, or a series connection of a variable resistor and a capacitor.

While the invention has been shown and described with reference to certain preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should not be limited to the above-described embodiments, but should be determined by the equivalents of the claims of the present invention as well as the claims of the following.

The present invention relates to a measuring apparatus, and it is possible to provide an apparatus for evaluating a voltage transformer comparator implemented to be movable.

Claims

A bias error evaluation circuit for measuring a bias error of the voltage transformer comparator;

A phase error evaluation circuit for measuring a phase error of said voltage transformer comparator; And

And a switch that couples the voltage error comparator to one of the error error evaluation circuit and the phase error evaluation circuit.
The method according to claim 1,

The error ratio evaluation circuit

A power supply for supplying power;

A variable resistor having one end connected to the power supply unit and having a variable resistance; And

And a fixed resistor whose one end is connected to the variable resistor and whose one end is connected to the contact of the power supply portion and the ground terminal.
3. The method of claim 2,

The switch unit

A first switch for connecting one end of a first resistor of the voltage transformer comparator to a ground terminal of the power supply unit and the variable resistor;

A second switch for connecting one end of the first resistor to the contact of the variable resistor and the fixed resistor for offset measurement;

A third switch for connecting one end of a second resistor of the voltage transformer comparator to a contact of the variable resistor and the fixed resistor; And

And a fourth switch for connecting the other end of the first resistor and the other end of the second resistor to a contact between the fixed resistor and the ground terminal.
The method of claim 3,

The third switch is turned off while the second switch is turned on to measure the offset of the error, and the second switch is turned off while the third switch is turned on.
The method of claim 3,

Wherein the first resistor is a primary resistor connected to the standard voltage transformer and the second resistor is a secondary resistor connected to a voltage transformer for testing.
The method of claim 3,

Wherein the first resistance is a secondary resistance connected to a voltage transformer for testing and the second resistance is a primary resistance connected to a standard voltage transformer when measuring a bias according to positive polarity.
3. The method of claim 2,

Wherein the variable resistor is adjusted to a resistance from 0.01 ohms to 200 ohms for the non-error calibration, and the fixed resistor has a resistance of 2 kilo ohms.
The method according to claim 1,

The phase error evaluation circuit

A power supply for supplying power;

A variable resistor having one end connected to the power supply unit and having a variable resistance; And

And a capacitor whose one end is connected to the variable resistor and whose one end is connected to the contact of the power supply part and the ground terminal.
9. The method of claim 8,

The switch unit

A first switch for connecting one end of a first resistor of the voltage transformer comparator to a ground terminal of the power supply unit and the variable resistor;

A second switch for connecting one end of the first resistor to the contact of the variable resistor and the capacitor for offset measurement;

A third switch for connecting one end of a second resistor of the voltage transformer comparator to the contact of the variable resistor and the capacitor; And

And a fourth switch for connecting the other end of the first resistor and the other end of the second resistor to a contact between the capacitor and the ground terminal.
10. The method of claim 9,

The third switch is turned off while the second switch is turned on to measure the offset of the error, and the second switch is turned off while the third switch is turned on.
10. The method of claim 9,

Wherein the first resistor is a primary resistor connected to the standard voltage transformer and the second resistor is a secondary resistor connected to a voltage transformer for testing.
10. The method of claim 9,

Wherein the first resistance is a secondary resistance connected to a voltage transformer for testing and the second resistance is a primary resistance connected to a standard voltage transformer when measuring a bias according to positive polarity.
10. The method of claim 9,

Wherein the variable resistor is adjusted to a resistance of 0.01 ohms to 200 ohms for the calibration of the bias error, and the capacitor has a capacitance of 2 uF.