KR100995251B1 - Current transformer comparator system - Google Patents

Abstract

The present invention is connected to the secondary current of the standard current transformer and the current transformer to be measured and the standard current transformer and the current transformer to be measured, the secondary current of the standard current transformer and the current transformer to be measured. The present invention relates to a calibration apparatus for a large current transformer including a current comparator to be compared and a load for a current transformer connected in series with the secondary side of the current transformer to be measured, and having a rated conversion ratio of 1: 1 and a power of 440 V / 225 A. A variable transformer receiving and supplying a maximum power of 440 V / 225 A; A plurality of large current generating transformers connected in parallel to receive power of the variable transformer to generate 20,000 A or more; A plurality of phase condenser connected in parallel with the large current generating transformer to cancel the ground current of the large current generating transformer to improve the power factor; A cylindrical busbar penetrating the center of the core of the standard current transformer, the current transformer to be measured, and the large current generating transformer, and having insertion diameters at both ends with a predetermined diameter and a predetermined length; 1,2 flanges coupled around both ends of the cylindrical bus bar; 3 flanges provided in the cylindrical bus bar between the 1,2 flanges; A plurality of high voltage lines connected around one side of the one flange and the three flanges; A movable rod for fixing and supporting the cylindrical busbar by being composed of a support rod inserted into the insertion grooves formed at both ends of the cylindrical busbar and a support portion coupled to the support rod; A plurality of c-shaped busbars coupled to the 2,3 flanges and having bent portions on both sides; wherein the standard current transformer and the large current generating transformer are located in a cylindrical busbar between the 2 flanges and the 3 flanges, The current transformer to be measured relates to a calibration device for a large current transformer, wherein the current transformer is located in a cylindrical busbar between one and three flanges.

Current transformer, busbar, current comparator, large current, power factor

Description

Calibration device for large current transformers {Current transformer comparator system}

The present invention relates to a calibration apparatus for calibrating high current transformers up to 20,000 A with an alternating current of 60 Hz.

Currently, the Korea Research Institute of Standards and Science, a representative organization of national measurement standards, has established AC high voltage / large current standards up to 13,200 V / 3,000 A and is distributing national standards to industries. It was not able to provide measurement support to the industry because it could not establish a system.

In addition, heavy electric equipment companies need to obtain international certification of high voltage high current test facilities in order to activate the export of heavy electric equipment products and strengthen international competitiveness.

Therefore, as the global trend of transmission voltage and power capacity increase, the voltage and current range of heavy electric equipment product test is greatly increased, and at the same time, the international reliability and transparency of test report, which is the core of quality assurance, are required at stricter level. As a result, international certification of heavy electric equipment testing and traceability from national standards are indispensable.

Accordingly, the present invention has been made to solve the above problems, an object of the present invention is to build a standard current transformer which is a standard of current transformers up to 20,000 A, using a current comparator to measure 20,000 A The present invention provides a calibration device for a large current transformer that performs a performance evaluation and calibration of a current transformer of 20,000 A by comparing and measuring the current transformer.

The object of the present invention as described above is connected to the standard current transformer and the current transformer to be supplied with the same current to the primary side, and the standard current transformer and the current transformer to be connected to the secondary side of the standard current transformer and the current transformer A calibration device for a large current transformer including a current comparator for comparing the secondary currents of a current transformer and a burden for a current transformer connected in series with the secondary side of the current transformer to be measured, wherein the rated conversion ratio is 1: 1 and 440 V / 225. A variable transformer for receiving power of A and supplying power of up to 440 V / 225 A; A plurality of large current generating transformers connected in parallel to receive power of the variable transformer to generate 20,000 A or more; A plurality of phase condenser connected in parallel with the large current generating transformer to cancel the ground current of the large current generating transformer to improve the power factor; A cylindrical busbar penetrating the center of the core of the standard current transformer, the current transformer to be measured, and the large current generating transformer, and having insertion diameters at both ends with a predetermined diameter and a predetermined length; 1,2 flanges coupled around both ends of the cylindrical bus bar; 3 flanges provided in the cylindrical bus bar between the 1,2 flanges; A plurality of high voltage lines connected around one side of the one flange and the three flanges; A movable rod for fixing and supporting the cylindrical busbar by being composed of a support rod inserted into the insertion grooves formed at both ends of the cylindrical busbar and a support portion coupled to the support rod; A plurality of c-shaped busbars coupled to the 2,3 flanges and having bent portions on both sides; wherein the standard current transformer and the large current generating transformer are located in a cylindrical busbar between the 2 flanges and the 3 flanges, The current transformer to be measured is achieved by a calibration device for a large current transformer, characterized in that it is located in a cylindrical busbar between one and three flanges.

According to the present invention, as the voltage and current range of heavy electric machine product test are greatly increased according to the increase of the transmission voltage and power capacity, which is a global trend, such high current / high voltage heavy electric machine can be evaluated and calibrated. It is effective in reducing product defect rate.

Hereinafter, with reference to the accompanying drawings showing a preferred embodiment of the present invention will be described in detail.

The present invention relates to a calibration apparatus of a full-current transformer for calibrating a current transformer up to 60 Hz, 20,000 A of alternating current, the calibration apparatus of such a large current transformer is a standard current transformer receiving the same current to the primary side (31a, 32a) (31) and the current transformer 32 to be measured and the secondary currents 31b and 32b of the standard current transformer 31 and the current transformer 32 to be measured are connected to the standard current transformer 31 and the current to be measured. A current comparator 60 for comparing the secondary side 31b and 32b currents of the transformer 32 and a burden 40 for the current transformer connected in series with the secondary side 32b of the current transformer 32 to be measured. And a variable transformer 10 having a rated conversion ratio of 1: 1 and receiving power of 440 V / 225 A, and receiving power of the variable transformer 10 to supply a maximum of 440 V / 225 A of power. A plurality of large current generating transformers 20 connected in parallel to generate more than 20,000 A, and the large current In order to offset the ground current of the biotransformer 20 to improve the power factor, a plurality of phase-capacitors 50 connected in parallel with the large current generating transformer 20, the standard current transformer 31 and the current transformer to be measured ( 32) and a cylindrical busbar 21 penetrating the center of the core of the large current generating transformer 20 and having a predetermined diameter and a predetermined length and forming insertion grooves 21a at both ends, and both ends of the cylindrical busbar 21. The first and second flanges 23 and 24 coupled to the circumference of the cylindrical bus bar 21 are provided on one side of the cylindrical bus bar 21 together with the one flange 23 and the two flanges 24 A, Three flanges 25 forming a section B, a plurality of high-voltage lines 70 connected around one side of the one flange 23 and the three flanges 25 and the insertion formed on both ends of the cylindrical bus bar 21 It consists of a support rod 81 inserted into the groove 21a and a support portion 82 coupled with the support rod 81 to fix the cylindrical busbar 21, The basement is configured to include a movable stator 80 and a plurality of c-shaped busbars 22 coupled to the 2,3 flanges 24 and 25 and having bent portions on both sides. Here, the standard current transformer 31 and the large current generating transformer 20 is located in section B of the cylindrical bus bar 21, and the current transformer 32 to be measured is located in section A of the cylindrical bus bar 21. Is characterized by

The output current of 20,000 A includes a variable transformer 10, a plurality of large current generating transformers 20, cylindrical busbars 21, 1,2,3 flanges 23, 24 and 25, and a c-shape. There is a bus bar 22, a high voltage line 70, and a fastening capacitor 50. When 20,000 A large current is generated, the maximum power of 440 V / 225 A is supplied to a plurality of large current generating transformers 20 using the variable transformer 10 having a rated conversion ratio of 1: 1 by receiving an input power of 440 V / 225 A. By the busbar 21, the 1,2,3 flanges 23,24,25, the high-voltage cable 70, and the U-shaped busbar 22, a test current of up to 20,000 A can be generated. To this end, the variable transformer 10 receives an input power of 440 V / 225 A, so that the rated conversion ratio is 1: 1, thereby supplying power of up to 440 V / 225 A (about 100 kVA) to the large current generating transformer 20. The same variable transformer 10 can be fine-tuned in the output voltage current range of 5% of the rating.

The large current generating transformer 20 is supplied with power of up to 440 V / 225 A through the variable transformer 10 to generate a current up to 20,000 A. The large current generating transformer 20 has the same capacity and specification as 2 or 3. It is configured to be connected in parallel with a large, and is connected to one side of the cylindrical bus bar 21 to be described later.

1,2,3 flanges (23,24,25), cylindrical busbar (21), c-shaped busbar (22) has a load resistance of about 300 μΩ, the standard current transformer 31 and the current transformer (32) It is manufactured to flow a current of 20,000 A or more to the primary sides 31a and 32a of the. To this end, the cylindrical bus bar 21 may have a diameter of 12 to 18 cm, a length of 1.7 to 2.5 m, and preferably a diameter of 15 cm and a length of 2.1 m. Such a cylindrical bus bar 21 is installed penetrating through the center of the core of the standard current transformer 31, the current transformer 32 to be measured, a plurality of large current generating transformer 20.

1,2,3 flanges (23,24,25) and the high-voltage cable 70 is provided for the connection of the cylindrical busbar 21 and the U-shaped busbar 22 and for easy replacement of the current transformer 32 under measurement. It is formed in a circular shape to increase the contact area, and is provided at both ends and one side of the cylindrical bus bar 21, the portion in contact with the cylindrical bus bar 21 and the U-shaped bus bar 22 is the contact resistance It is plated with silver to reduce. The easy replacement of the current transformer 32 to be measured is 1,2,3 flanges (23,24,25) by dividing the section A and the section B of the cylindrical busbar 21 to the 1,2 flanges 23, 24, the space where the current transformer 32 to be measured is to be positioned rather than the c-shaped busbar 22, that is, the section A is provided with a separate high voltage line 70 and a three flanges 25 to be connected in the future. When replacing the measuring current transformer 32, it is easier to handle the high-voltage cable 70 that is lighter than the heavy c-shaped busbar 22.

The c-shaped busbar 22 may have a length of 2 to 2.6 m, a width of 12 to 18 cm, and a thickness of 12 to 18 mm, preferably a length of 2.3 m, a width of 15 cm, and a thickness of 15 mm. Configure. The U-shaped busbars 22 have bent portions on both sides, and the overall shape is similar to “c”, and the ends of the bent portions are radially 2,3 with respect to the centers of the 2,3 flanges 24 and 25. Engage with flanges 24 and 25. At this time, a portion of the c-shaped bus bar 22 which is in contact with the 2,3 flanges 24 and 45 is silver plated to reduce contact resistance, and thus a large current of up to 30,000 A may flow.

The phase advance capacitor 50 is connected in parallel to the large current generating transformer 20 to cancel the ground current caused by the inductive reactance caused by the coil component of the large current generating transformer 20 to improve the power factor. Up to 15 fast capacitors 50 with the same capacity of 440 V, 20 kVA are connected in parallel. On the other hand, the fastening capacitor 50 is connected to the plurality of large current generating transformer 20 and the test capacitor in parallel according to the test current to adjust the capacitance value so that the power factor is close to 1 of the large current generating transformer 20 Contributes to increased efficiency.

The current comparator 60 is connected to the standard current transformer 31 and the secondary sides 31b and 32b of the current transformer 32 to be supplied with equally large currents up to 20,000 A on the primary side, and the secondary side of the current transformers. It is configured to compare the current and measure the error and phase angle error.

The standard current transformer 31 provides a reference for measuring the error and phase angle error of the current transformer 32 under measurement, and the error of the standard current transformer 31 is 10 than the error of the current transformer 32 under measurement. The error of the standard current transformer 31 may be negligible by more than twice, and may vary depending on the range of the primary current I _p and the secondary current I _s . One example is the standard current transformer with 5000 A and 20,000 A primary currents.

The 5000 A standard current transformer (Type 4764, S / N: 153606) manufacturer's measurement results show the error and phase angle error for all current ranges up to 5,000 A and the burden of 0 VA and 5 VA / PF = 1 The value is within 0.001% and 0.02 min. This satisfies the manufacturer's specifications considering that the manufacturer's specifications of the standard current transformer above are ≤ ± 0.001% and the phase angle error is ≤ ± 0.05 min.

Meanwhile, another example of the standard current transformer 31 may include a 20,000 A standard current transformer (Type: NCD 20000d, S / N: 2/06/0006). The measurement result of the 20,000 A standard current transformer manufacturer satisfies the manufacturer's specifications with a tolerance of ≤ ± 0.005% and a phase angle error of ≤ ± 0.5 min.

The burden 40 for the current transformer is connected in series to the secondary side of the current transformer 32 under test, which is based on the KS standard for measuring the error and phase angle error of the current transformer.

Since the error of the current transformer 32 to be measured depends on the burden value and the power factor, accurate measurement of the burden value and the power factor is very important for the precise measurement of the non-error and phase angle error of the current transformer 32 to be measured. The burden value and power factor of the burden 40 can be measured by an automatic measurement program, and the results of the measurement are shown in Table 1.

rated burden setting value measured value burden (VA) power factor burden (VA) power factor 1 VA 1.00 1.00 1.001 1,000 1.25 VA 1.25 1.00 1.251 0.999 2.5 VA 2.50 1.00 2.496 0.999 3.75 VA 3.75 1.00 3.746 1,000 5 VA 5.00 1.00 5.003 1,000 7.5 VA 7.50 1.00 7.459 1,000 10 VA 10.0 1.00 10.02 1,000 12.5 VA 12.5 1.00 12.53 1,000 15 VA 15.0 1.00 15.06 1,000

Hereinafter, the method of measuring the error and phase angle error of the current transformer to be measured by the present invention as described above will be described.

First, using the cylindrical bus bar 21 and the c-shaped bus bar 22 before measuring the error and phase angle error of the current transformer 32 under measurement using the current transformer comparison measuring device according to the present invention. The output stability of 20,000 A large current was investigated. The output of the current 20,000 A measures the stability of the current generating source of 20,000 A by attaching a resistance of 0.4 Ω to the secondary side of the current transformer in which the ratio of primary current and secondary current is 20,000 A: 5 A. It was. 5 is a result of measuring a large current of 20,000 A while flowing for 10 minutes. The reason why the output current decreases gradually with time is that heat is generated in the cylindrical busbar 21 and the c-shaped busbar 22 so that the resistance of the cylindrical busbar 21 and the c-shaped busbar 22 is increased. Because. The relative standard deviation of the stability of the output current was very good at 0.12%. Considering that the measurement time of the current transformer 32 to be measured is typically about 2 to 3 minutes, it can be seen that the output stability is hardly affected by the measurement.

FIG. 6 measured the current waveform of the secondary side of the current transformer of 20,000 A: 5 A when a current of 20,000 A flowed using a digital oscilloscope. It can be seen that there is no distortion of the large current sinusoid when the 20,000 A current is energized.

Referring to the operation relationship of the calibration apparatus of the large current transformer according to the present invention under the above conditions are as follows.

The calibrating device of the large current transformer constructed this time can calibrate the current transformer 32 under measurement of the primary current I _p = 0.05 A to 20,000 A. The calibration apparatus of the large current transformer uses two standard current transformers 31 according to the current measurement range of the current transformer 32 to be measured. When the primary side current I _p = 5 000 A or more of the current transformer 32 to be measured, a cylindrical busbar 21 having a diameter of 15 cm is used by using a standard current transformer having a primary current I _p = 5,000 A to 20,000 A. To measure the error and phase angle error of the current transformer 32 under measurement.

On the other hand, when the primary side current I _p of the current transformer 32 to be measured is less than 5,000 A, and the primary side is a through-type, a 5,000 A standard current transformer and a cylindrical busbar 21 having a diameter of 7 cm are used. The measurement error and phase error of the current transformer 32 is measured.

In the above two cases, the measuring method is a cylindrical bus bar 21 and a c-shaped bus bar 22, in which the same current is serially connected to the primary side of the standard current transformer 31 and the current transformer 32 under measurement. Supply and compare the currents on the secondary side of the two current transformers using the current comparator 60 to measure the error and phase error of the current transformer 32 to be measured. This method measures the error and phase angle error of the current transformer 32 under measurement based on the standard current transformer 31 which can ignore the error and phase angle errors compared to the current transformer 32 under measurement. As a result of the test operation, it was confirmed that the test of the current transformer to the primary current of 20,000 A operates normally. In addition, the current transformer comparator was able to confirm that the variation of the error and the phase error were very stable within 0.0002% and 0.005 min, respectively.

Hereinafter, the results of evaluating the performance of the calibration device of the large current transformer according to the present invention in preparation for international comparative measurement.

In order to evaluate the performance of the calibration equipment of the large current transformer, an international comparison with the Australian National Standards Institute (NMIA) was performed using a 5,000 A current transformer (type P-5000, S / N: 0490961) as a mobile standard current transformer. Measurements in the KRISS were made using a 5,000 A standard current transformer (type 4764, S / N: 153606) and a copper busbar 7 cm in diameter. Since the non-error and phase angle error of the current transformer 32 under measurement are measured based on the standard current transformer 31, the relationship between the non-error measurement value of the current transformer 32 under measurement and the actual error is as follows.

= 실제 피측정 전류변성기의 비오차, here

= Error of the current transformer to be measured,

= 표준 전류변성기의 비오차,

= Error of the standard current transformer,

= 전류변성기 비교기에서 측정되는 비오차.

= Non-error measured in the current transformer comparator.

In order to calculate the error of the actual current transformer 32 under Equation 1, the error value of the standard current transformer 31 is added to the value measured by the current comparator 60 to be corrected. This correction value was taken from the measured value of the 5,000 A standard current transformer manufacturer, and the error of the actual current transformer 32 to be measured was obtained. The results of non-error measurements at KRISS are shown in the third column of Table 2. Here, the measurement conditions are 5%, 20% and 100% of the secondary side currents in the range of 0 VA, 60 Hz, and the primary side currents of the current transformer of 10 A to 3,000 A.

On the other hand, the results of non-error measurements in Australia NMIA under the same test conditions using the same mobile current transformer measured by KRISS are shown in the fourth column of Table 2. The discrepancies in both organs are shown in the last column of Table 2, which shows a fairly good agreement with a maximum of 0.002%.

Rated primary current /
Rated secondary current Secondary
current (%) Ratio error (%) Difference
(KRISS-NMIA) KRISS NMIA 10 A / 5 A 5
20
100 +0.000
-0.001
-0.001 +0.000
+0.000
+0.000 +0.000
-0.001
-0.001 15 A / 5 A 5
20
100 +0.000
-0.001
-0.001 +0.000
+0.000
+0.000 +0.000
-0.001
-0.001 20 A / 5 A 5
20
100 +0.000
-0.001
-0.001 +0.000
+0.000
+0.000 +0.000
-0.001
-0.001 25 A / 5 A 5
20
100 +0.000
-0.001
-0.001 +0.000
+0.000
+0.000 +0.000
-0.001
-0.001 50 A / 5 A 5
20
100 +0.000
-0.001
-0.001 +0.001
+0.000
+0.000 -0.001
-0.001
-0.001 75 A / 5 A 5
20
100 +0.000
-0.001
-0.002 +0.001
+0.000
+0.000 -0.001
-0.001
-0.002 100 A / 5 A 5
20
100 -0.001
-0.001
-0.002 +0.000
+0.000
-0.001 -0.001
-0.001
-0.001 300 A / 5 A 5
20
100 +0.000
-0.001
-0.002 +0.000
+0.000
+0.000 +0.000
-0.001
-0.002 600 A / 5 A 5
20
100 -0.001
-0.001
-0.001 +0.001
+0.000
+0.000 -0.002
-0.001
-0.001 750 A / 5 A 5
20
100 +0.000
-0.001
-0.001 +0.000
+0.000
-0.001 +0.000
-0.001
+0.000 1000 A / 5 A 5
20
100 +0.000
-0.001
-0.001 +0.000
-0.001
-0.001 +0.000
+0.000
+0.000 1500 A / 5 A 5
20
100 +0.001
+0.000
-0.001 +0.000
+0.000
-0.001 +0.001
+0.000
+0.000 2000 A / 5 A 5
20
100 +0.001
+0.000
+0.000 -0.001
-0.001
-0.001 +0.002
+0.001
+0.001 3000 A / 5 A 5
20
100 +0.000
+0.000
-0.001 -0.002
-0.002
-0.002 +0.002
+0.002
+0.001

Similarly to Equation 1, the relationship between the phase angle error measurement value of the current transformer 32 under test and the phase angle error of the current transformer 32 under measurement is as follows.

= 실제 피측정 전류변성기의 위상각 오차here

= Phase angle error of the current transformer

= 표준 전류변성기의 위상각 오차,

= Phase angle error of standard current transformer,

= 전류변성기 비교기에서 측정되는 위상각 오차.

= Phase angle error measured by the current transformer comparator.

In order to calculate the phase angle error of the current transformer 32 to be measured in Equation 2, the phase angle error value of the standard current transformer 31 is added to the value measured by the current comparator 60 to be corrected. This correction value was taken from the measured value of the 5,000 A standard current transformer manufacturer, and the phase angle error of the actual current transformer 32 to be measured was obtained. Phase angle error measurement results in KRISS are shown in the third column of Table 3. Here, the measurement conditions are the same as in the previous measurement of the error.

The results of phase angle error measurements in Australia NMIA for the same test conditions using the same mobile current transformer 31 measured by KRISS are shown in the fourth column of Table 3. The discrepancies in both organs are shown in the last column of Table 3, with a fairly good agreement of up to 0.09 min.

Rated primary current /
Rated secondary current Secondary
current (%) Phase displacement (min) Difference
(KRISS-NMIA) KRISS NMIA 10 A / 5 A 5
20
100 +0.09
+0.04
-0.04 +0.00
+0.00
-0.07 +0.09
+0.04
+0.03 15 A / 5 A 5
20
100 +0.10
+0.04
-0.05 +0.03
+0.00
-0.07 +0.07
+0.04
+0.02 20 A / 5 A 5
20
100 +0.09
+0.04
-0.05 +0.00
-0.03
-0.07 +0.09
+0.07
+0.02 25 A / 5 A 5
20
100 +0.09
+0.03
-0.05 +0.00
+0.00
-0.07 +0.09
+0.03
+0.02 50 A / 5 A 5
20
100 +0.08
+0.02
-0.07 +0.03
+0.00
-0.07 +0.05
+0.02
+0.00 75 A / 5 A 5
20
100 +0.07
+0.01
-0.08 +0.03
+0.00
-0.07 +0.04
+0.01
-0.01 100 A / 5 A 5
20
100 +0.07
+0.01
-0.09 +0.07
+0.00
-0.03 +0.00
+0.01
-0.06 300 A / 5 A 5
20
100 +0.09
+0.02
-0.07 +0.03
+0.00
-0.03 +0.06
+0.02
-0.04 600 A / 5 A 5
20
100 +0.08
+0.01
-0.08 +0.07
+0.00
-0.03 +0.01
+0.01
-0.05 750 A / 5 A 5
20
100 +0.06
+0.01
-0.07 +0.07
+0.03
-0.03 -0.01
-0.02
-0.04 1000 A / 5 A 5
20
100 +0.03
-0.01
-0.07 +0.07
+0.00
-0.03 -0.04
-0.01
-0.04 1500 A / 5 A 5
20
100 +0.09
+0.03
-0.03 +0.07
+0.03
-0.03 +0.02
+0.00
+0.00 2000 A / 5 A 5
20
100 +0.06
+0.02
-0.04 +0.10
+0.03
-0.03 -0.04
-0.01
-0.01 3000 A / 5 A 5
20
100 +0.04
+0.00
-0.05 +0.07
+0.03
-0.03 -0.03
-0.03
-0.02

On the other hand, in order to evaluate the performance of the calibration device of the large current transformer, the German national standard is used by using a 20 kA current transformer (NCD 20000d, S / N: 2/06/0006) as a mobile current transformer in a similar manner to the previous international comparison with Australia. International comparisons were conducted indirectly with the PTB.

Measurements in the KRISS were measured using a cylindrical busbar 21 having a diameter of 15 cm to generate a current of 20,000 A. As the standard current transformer 31, a 20,000 A current transformer (NCD 20000d, S / N: 2/06/0007) was used. The non-error measurement value of the actual current transformer 32 under measurement in KRISS was obtained in the same manner as in <Equation 1>. The measurement conditions at both engines are 10%, 20%, 50% and 100% of secondary side currents in the range of 5 VA, PF = 1, 60 Hz and primary side currents of 5,000 A to 20,000 A of current transformers. Non-error measurements at both organs are shown in Table 4, and the last column of Table 4 shows the difference in measurements at both organs. The discrepancies in both organs are up to 0.004%, which shows a fairly good agreement.

Rated primary current /
Rated secondary current Secondary
current (%) Ratio error (%) Difference
(KRISS-PTB) KRISS PTB 5000 A / 5 A 10
20
50
100 +0.004
+0.004
+0.004
+0.003 +0.007
+0.007
+0.007
+0.007 -0.003
-0.003
-0.003
-0.004 10000 A / 5 A 10
20
50
100 +0.008
+0.008
+0.007
+0.007 +0.010
+0.010
+0.010
+0.010 -0.002
-0.002
-0.003
-0.003 15000 A / 5 A 10
20
50
100 +0.006
+0.006
+0.005
+0.005 +0.008
+0.008
+0.007
+0.007 -0.002
-0.002
-0.002
-0.002 20000 A / 5 A 10
20
50
100 +0.004
+0.003
+0.003
+0.003 +0.007
+0.007
+0.006
+0.006 -0.003
-0.004
-0.003
-0.003

As in Table 4, Table 5 shows the measurement results of the phase angle errors measured by both engines. The inconsistency in both organs is up to 0.1 min, which shows a fairly good agreement.

Rated primary current /
Rated secondary current Secondary
current (%) Phase angle error (min) Difference
(KRISS-PTB) KRISS PTB 5000 A / 5 A 10
20
50
100 -0.5
-0.6
-0.6
-0.7 -0.5
-0.6
-0.6
-0.6 +0.0
+0.0
+0.0
-0.1 10000 A / 5 A 10
20
50
100 -0.1
-0.1
-0.3
-0.3 -0.2
-0.2
-0.2
-0.2 +0.1
+0.1
-0.1
-0.1 15000 A / 5 A 10
20
50
100 -0.1
-0.1
-0.2
-0.2 -0.2
-0.2
-0.2
-0.2 +0.1
+0.1
+0.0
+0.0 20000 A / 5 A 10
20
50
100 -0.2
-0.2
-0.2
-0.2 -0.1
-0.1
-0.1
-0.2 -0.1
-0.1
-0.1
+0.0

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is evident that many alternatives, modifications, and variations will readily occur to those skilled in the art without departing from the spirit and scope of the invention. Therefore, it should be understood that the disclosed embodiments are to be considered in an illustrative rather than a restrictive sense, and that the true scope of the invention is indicated by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof, .

1 is a view showing an example of a calibration device of a 20,000 A large current transformer according to the present invention;

2 is a view showing separately the main part of FIG.

3 is a view showing a configuration separated to replace the current transformer to be measured according to the present invention,

FIG. 4 is a view illustrating sections A and B separately illustrating two main parts of FIG. 1;

5 is a block diagram schematically showing the configuration of a calibration apparatus for a high current transformer according to the present invention;

Figure 6 is a graph showing the stability of the current over time at 20,000 A large current energization in the calibration device of the high current transformer according to the present invention,

7 is a graph showing a sinusoidal waveform of a large current at the time of energizing 20,000 A in a high current transformer according to the present invention;

8 is a photograph showing a calibration device for a 5,000 A large current transformer according to the present invention.

Description of the Related Art

10: variable transformer 20: large current generating transformer

21: cylindrical busbar 22: c shaped busbar

23: 1 flange 24: 2 flanges

25: 3 flanges

31: Standard current transformer 32: Current transformer

31a, 32a: Primary side of standard current transformer and current transformer

31b, 32b: secondary side of standard current transformer and current transformer

40: Burden 50: Truth condenser

60: current comparator 70: power cable

Claims (9)

The standard current transformer 31 and the current transformer 32 to be supplied with the same current to the primary sides 31a and 32a, and the secondary side 31b of the standard current transformer 31 and the current transformer 32 to be measured 32. 32b), a current comparator 60 for comparing the currents of the standard current transformer 31 and the secondary side 31b, 32b of the current transformer 32 to be measured, and the secondary side of the current transformer 32 to be measured. In the calibrating device of a high current transformer configured to include a load 40 for the current transformer connected in series with (32b), A variable transformer having a rated conversion ratio of 1: 1 and receiving a power of 440 V / 225 A and supplying a maximum of 440 V / 225 A; A plurality of large current generating transformers 20 connected in parallel to receive power of the variable transformer 10 to generate 20,000 A or more; A plurality of fastening capacitors 50 connected in parallel with the large current generating transformer 20 to cancel the ground current of the large current generating transformer 20 to improve the power factor; Cylindrical bus bar penetrating the center of the core of the standard current transformer 31, the current transformer 32 and the large current generating transformer 20, and having insertion diameters 21a at both ends having a predetermined diameter and a predetermined length ( 21); 1,2 flanges (23, 24) coupled to both ends of the cylindrical bus bar (21); A three flange 25 provided in the cylindrical bus bar 21 between the first and second flanges 23 and 24; A plurality of high voltage lines (70) connected around one side of the one flange (23) and the three flanges (25); The support rod 81 is inserted into the insertion groove 21a formed at both ends of the cylindrical bus bar 21 and the support portion 82 coupled to the support bar 81 to fix and support the cylindrical bus bar 21. A movable holder 80; A plurality of c-shaped busbars 22 coupled to the second and third flanges 24 and 25 and having bent portions on both sides; The standard current transformer 31 and the large current generating transformer 20 is located in the cylindrical busbar 21 between the two flange 24 and the three flange 25, The current transformer (32) to be measured is a calibration device for a large current transformer, characterized in that located in the cylindrical bus bar (21) between one flange (23) and three flanges (25). The method of claim 1, The 1,2,3 flanges (23, 24, 25), the cylindrical bus bar 21, and the c-shaped bus bar 22, the resistance of the high current transformer, characterized in that the use is made of 300 μΩ or less . The method of claim 1, The surface of the 1,2,3 flanges (23,24,25) by plating the surface of the high current transformer, characterized in that to improve the conductivity of the cylindrical bus bar (21) and the c-shaped bus bar (22). The method of claim 1, The fastening capacitor 50 is a calibration of a large current transformer, characterized in that to use the capacity of 440 V, 20 kVA to improve the efficiency of the large current generating transformer 20 by adjusting the capacitance value so that the power factor is close to 1 Device. The method of claim 1, Fine adjustment of the variable transformer (10) is a calibration device of a large current transformer, characterized in that the output voltage current is in the range of 5% of the rating. The method of claim 1, The plurality of large current generating transformer 20 is a calibration device for a large current transformer, characterized in that the capacity and specifications are configured to be the same to generate a large current of 20,000 A. The method of claim 1, The c-shaped bus bar 22 is provided with a plurality of correction apparatus of the high current transformer, characterized in that coupled to the radially symmetrical with respect to the center of the 2,3 flanges (24,25). The method of claim 1, The cylindrical busbar 21 has a diameter of 12 to 18 cm, the length of the calibration device of a large current transformer, characterized in that 1.7 to 2.5 m. The method of claim 1, The c-shaped busbars 22 have a length of 2 to 2.6 m, a width of 12 to 18 cm, and a thickness of 12 to 18 mm.

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