CT tester

CT testeruseScope and Technical Indicators

1.1 Function and usage scenarios

The following tests are used for current transformers:

1) Excitation characteristic test

2) Turn ratio detection

3) Comparison and angle difference verification

4) Polarity verification

5) Measurement of secondary winding resistance

6) Secondary load measurement

7) 5% and 10% error curve measurement

8) CT transient characteristic testing and analysis

9) CT nameplate automatic inference

10) Measurement of CT parameters such as inflection point voltage/current, accuracy limit factor, instrument security factor, secondary time constant, remanence coefficient, accuracy level, saturation and unsaturation, inductance, inflection point electromotive force, ultimate electromotive force, and area coefficient

11) Measurement of hysteresis loop of current transformer core

It can also be used for the following tests of voltage transformers:

1) PT turns ratio detection

2) PT polarity verification

3) Measurement of PT secondary winding resistance

4) PT secondary load measurement

5) Measurement of PT excitation characteristics

The main application scenarios of the device are:

1) Parameter verification of CT nameplate

2) Parameter verification when CT is connected to the current load

3) Analyze the transient characteristics of CT and its impact on relay protection devices.

4) Calibration of PT nameplate parameters

5) PT secondary load verification

1.2 Technical specifications of CTPT analyzer

1. Test standard basis:

IEC60044-1, IEC60044-2, IEC60044-5, IEC60044-6, GB1207, GB1208,GB16847, GBT4703, C57.13

2 Input power supply voltage: AC220V ± 10%, 50Hz/60Hz ± 10%

3 Output voltage: 0.1~180V (AC)

4 Output current: 0.001~5A (RMS)

5 output power: 500VA

6 High Equivalent Turning Point Voltage: 45KV

7 Current Measurement: Range: 0~10A (Automatic Range: 0.1/0.4/2/10A)

Error<± 0.1%+0.01% FS

8 Voltage measurement: Range: 0~200 V (automatic range 1/10/70/200V)

Error<± 0.1%+0.01% FS

9-turn ratio measurement: range: 1~35000,

1-2000 error<0.05%

2000~5000 error<0.1%

5000~35000 error<0.2%

10 phase measurement: accuracy: ± 2min, resolution: 0.01min

11. Measurement range of secondary winding resistance: 0~8K Ω (automatic range 2/20/80 Ω/800 Ω/8k Ω)

Error<0.2% RDG+0.02% FS, high resolution: 0.1m Ω

12 Temperature measurement: -50~100 degrees, error<3 degrees

13 CT secondary load measurement: 0-160 ohm (2/20/80 ohm/160 ohm)

*. 2% RDG+0.02% FS high resolution 0.001ohm

14 PT secondary load measurement: 0-80kohm (800ohm/8kohm/80kohm)

*0.2% RDG+0.02% FS high resolution 0.1 ohm

15 PT turns ratio measurement: range: 1~30000,

1~5000 error<0.2%

5000~30000 error<0.5%

16 can automatically evaluate the test results according to the selected standards and determine whether the transformer is qualified

17 can simultaneously detect the ratio difference and angle difference of current mutual inductance under rated load and operating load

18 has the function of automatically generating WORD test reports

19 has the function of batch production of WORD test reports, which can produce all selected test files into standardized WORD reports at once

20 can automatically compare the excitation curve with the stored historical curve

21 data storage groups: greater than 1000 groups

22 Working conditions: temperature: -10 ℃~50 ℃, humidity: ≤ 90%

23 Dimensions: 485mm × 356mm × 183mm

24 weight: 15Kg

Chapter 2CT testerHardware device

2.1 Overview

The appearance and description of each part are shown in Figure 2.1

2.2 Power Connection

The power input socket is located on the right side of the instrument panel, as shown in Figure 2.2. The power input range is AC220 ± 10%, 50/60Hz ± 10%, and the power socket is equipped with a 5A fuse inside.

2.3 Input and Output

There are three sets of test interfaces: power output, CT secondary side/PT primary side input, CT primary side/PT secondary side input.

Power output terminal: power output interface, output voltage range is AC 0~180V, output current is AC 0~5A

CT secondary/PT primary input terminals:

CT secondary winding/PT primary winding voltage measurement input interface, the voltage range of the input signal is AC0-180V

CT primary/PT secondary input terminals: CT primary/PT secondary winding voltage measurement input interface, input signal voltage range is AC0-5V

2.4 Hardware Principle Block Diagram

The structural principle is shown in Figure 2.3, where the constant voltage and constant current variable frequency power supply module is isolated from the AC220V power input. By using a DSP data acquisition system to control the constant voltage and current module, the power supply can output AC 0~180V sine voltage signals or AC 0~1A sine current signals.

The main function of the DSP data acquisition system is to complete the data acquisition for the control and testing process of the variable frequency power supply. All data analysis, storage, and interface display are completed by the industrial computer system. The industrial computer is equipped with an embedded XPE system and self recovery protection for the system's C drive, which can effectively avoid software system failures and virus attacks. The internal storage space of the instrument is greater than 6G, and the large storage data is greater than 1000 sets.

2.5 Keyboard

The panel is equipped with a 16 key keypad for data input, as shown in Figure 2.4. The definition of each key is as follows:

1) 0-9 numeric input keys

2) ∧ Select up arrow key

3) ∨ Select the directional key downwards

4) Delete data key

5). Decimal point input key

6) ESC Deselect Key

7) Confirm selection or input key

Chapter 3 Experimental Connection

3.1 CT secondary load

When conducting CT secondary load measurement, please connect the analyzer and the measured CT according to Figure 3.1

The specific wiring steps and instructions are as follows:

1) Connect the grounding pole to the protective ground PE

2) Disconnect the CT secondary side and secondary circuit as shown in Figure 3.1

3) Connect the black terminals of the power output and CT secondary/PT primary side to the secondary load side, as shown in Figure 3.1

4) Connect the red terminals of the power output and CT secondary/PT primary side to the other side of the secondary load

5) In order to eliminate the influence of contact resistance, the connection terminal on the CT secondary side should be kept inside the power output terminal when connecting the terminals, as shown in Figure 3.2.

Attention: When conducting CT secondary load measurement, it is necessary to disconnect the connection between the tested CT secondary side and the load, otherwise the measurement result will be the parallel impedance between the CT secondary side and the secondary load, which will cause the instrument to obtain incorrect test results. And during the secondary load measurement, the instrument does not demagnetize, so if the CT secondary side is not disconnected, it will cause the CT to enter a saturated state.

3.2 CT analysis, transformation ratio, polarity test wiring diagram

When conducting CT analysis, transformation ratio or polarity tests, please connect the analyzer and the tested CT according to Figure 3.3. The wiring method for these three test items is *

The specific wiring steps and instructions are as follows:

1) Disconnect the power line from the primary side of the CT. The ungrounded power line is longer and can introduce significant interference to the measurement on the primary side of the CT, as shown in Figure 3.4.

3) Connect one end of the CT primary side to the black terminal on the CT primary/PT secondary side of the analyzer

4) Connect the other end of the CT primary side to the red terminal of the CT primary/PT secondary side of the analyzer

5) Connect the grounding column of the analyzer to the protective ground PE

6) Disconnect the connection between the secondary side of the CT being tested and the secondary load as shown in Figure 3.3

7) Connect the black terminals of the power output and CT secondary/PT primary side to one end of the CT secondary side, as shown in Figure 3.3

8) Connect the red terminals of the power output and CT secondary/PT primary side to the other end of the CT secondary side

9) In order to eliminate the influence of contact resistance on coil resistance measurement, when connecting the terminals of the analyzer, the CT secondary side/PT primary side connection terminal should be kept inside the power output terminal, as shown in Figure 3.4.

Attention: When conducting CT analysis or CT ratio difference angle test on multi winding current transformers with the same transformation ratio, all untested secondary windings should be short circuited, otherwise the test error will be biased

For example, when measuring the differential angle difference of the 0.5 level winding, protecting 10P10, and transient TPY with a CT of 2000/1, the wiring should be carried out according to Figure 3.4.1 when measuring the differential angle difference of the 0.5 level winding

3.3 CT coil resistance measurement wiring diagram

When measuring the DC resistance of the CT coil, please connect the instrument and the measured CT according to Figure 3.5.

1) Connect the grounding column of the CTPT analyzer to the protective ground PE

2) Disconnect the connection between the secondary side of the CT being tested and the secondary load as shown in Figure 3.5

3) Connect the black terminals of the power output and CT secondary/PT primary side to one end of the CT secondary side, as shown in Figure 3.5

4) Connect the red terminals of the power output and CT secondary/PT primary side to the other end of the CT secondary side

5) In order to eliminate the influence of contact resistance on coil resistance measurement, when connecting the terminals of the analyzer, the CT secondary side/PT primary side connection terminal should be kept inside the power output terminal, as shown in Figure 3.4.

3.4 PT secondary load

Please connect the CTPT analyzer and the tested PT according to Figure 3.6 when conducting PT secondary load measurement

The specific wiring steps and instructions are as follows:

1) The grounding pole is connected to the protective ground PE

2) Disconnect the PT secondary side and secondary circuit as shown in Figure 3.6

3) Connect the black terminals of the power output and CT secondary/PT primary side to one end of the secondary load, as shown in Figure 3.6

4) Connect the CTPT analysis power output and the red terminals on the CT secondary/PT primary side to the other end of the secondary load

5) In order to eliminate the influence of contact resistance, when connecting terminals, the CT secondary side/PT primary side connection terminal should be kept inside the power output terminal, as shown in Figure 3.2.

3.5 PT coil resistance measurement wiring diagram

When measuring the DC resistance of the PT coil, please connect the instrument and the tested PT according to Figure 3.7.

1) The grounding pole is connected to the protective ground PE

2) According to Figure 3.7, disconnect the connection between the secondary side of the tested PT and the secondary load, or disconnect the connection between the primary side of the PT and the primary line of the PT

3) Connect the black terminals of the power output and CT secondary/PT primary side to one end of the PT secondary (or PT primary) side, as shown in Figure 3.7

4) Connect the CTPT analysis power output and the red terminals on the CT secondary/PT primary side to the other end of the PT secondary (or PT primary) side

5) In order to eliminate the influence of contact resistance on coil resistance measurement, the connection terminals of CT secondary side/PT primary side should be kept inside the power output terminal when connecting terminals, as shown in Figure 3.4.

3.6 PT turns ratio, polarity test wiring diagram

When conducting PT ratio or polarity tests, please connect the CTPT analyzer and the tested PT according to Figure 3.9. The wiring method for these two test items is *

The specific wiring steps and instructions are as follows:

1) Connect one end of the PT secondary side to the black terminal on the CT primary/PT secondary side of the analyzer

2) Connect the other end of the PT secondary side to the red terminal on the CT primary/PT secondary side of the analyzer

3) The grounding pole is connected to the protective ground PE

4) Disconnect the secondary side of the tested PT from the secondary load as shown in Figure 3.9

5) Connect the black terminals of the power output and CT secondary/PT primary side to one end of the PT primary side, as shown in Figure 3.9

6) Connect the CTPT analysis power output and the red terminals on the CT secondary/PT primary side to the other end of the PT primary side

7) In order to eliminate the influence of contact resistance on coil resistance measurement, when connecting the terminals of the analyzer, the CT secondary side/PT primary side connection terminal should be kept inside the power output terminal, as shown in Figure 3.4.

3.7 PT excitation test wiring diagram

Please connect the analyzer and the tested PT according to Figure 3.10 during the PT excitation test.

When performing PT excitation test, an external PT excitation test module is required to prevent high-frequency oscillation and excessive current in the test results

The specific wiring steps and instructions are as follows:

1) Connect one end of the PT secondary side to the black terminal on the CT secondary/PT primary side of the CTPT analyzer

2) Connect the other end of the PT secondary side to the red terminal on the CT secondary/PT primary side of the CTPT analyzer

3) Connect the yellow/black wires of the PT excitation module to the power output of the analyzer

4) Connect one end of the PT secondary side to the red socket of the PT excitation module

5) Connect the other end of the PT secondary side to the black socket of the PT excitation module

6) The grounding pole is connected to the protective ground PE

7) Disconnect the connection between the secondary side of the tested PT and the secondary load as shown in Figure 3.10

8) In order to eliminate the influence of contact resistance on coil resistance measurement, when connecting the terminals of the analyzer, the CT secondary side/PT primary side connection terminal should be kept inside the power output terminal, as shown in Figure 3.4.

Attention: After the PT excitation test is completed, there may be residual high voltage on the PT primary side. It is necessary to discharge the PT primary side, otherwise connecting it to the instrument again may cause instrument loss

Chapter 4 User Interface

4.1 Instrument operation interface

The software system defines six operating states, which are "waiting to create a new experiment", "waiting to view historical results", "waiting for experiment", "running", "viewing results", and "viewing historical results". The software display interface is different in different states, but the entire software interface is divided into 5 areas, as shown in Figure 4.1. The 5 areas are respectively the toolbar, the instrument main working area (displayed as test item selection and operation command selection in the waiting test interface, as shown in Figure 4.1), the instrument status information column, the current test parameters column, and the test control column. When the instrument is in different operating states, it only switches the display interface in the main workspace.

4.2 Instrument software toolbar

The toolbar contains various command buttons for instrument operations, including "New Test", "Save", "Read", "Instrument Settings", "Language Selection", "Transformer Settings", "Data Export", and "Usage Help". The detailed explanations of each instrument control command are as follows.

4.2.1 New experiment

New test refers to ending the current test window and returning the software to the "waiting for new test state". In this state, the interface shown in Figure 4.1 is loaded, and the test items to be carried out can be selected in this window. The test items in this window include "CT analysis", "CT differential angle measurement", "CT secondary load", "CT polarity check", "CT coil resistance measurement", "PT ratio", "PT secondary load", "PT polarity check" and "PT coil resistance". The software can also be restarted or the system can be shut down in this state.

4.2.2 Save

The save button is used to save the instrument test results and data after completing the experiment. When viewing historical results, if the user modifies the current display mode (standard or transformer level change), this button can be used to save the modified results.

The instrument organizes the file names in the following format when saving test results:

Year Month Day Hour: Minute: Second Transformer Number Test Name. cta

For example, CT analysis on April 8, 2011 at 11:12:30. CTA

The time part is taken from the system time at the moment of starting the experiment. Therefore, after viewing the historical result status and modifying the experiment display mode, the experiment results will be saved. At this time, the instrument will automatically overwrite the original file without creating a new copy for this file.

4.2.3 Reading

The function of the read button is to re import saved historical data. When the user clicks the read button, the window shown in Figure 4.2 will be loaded.

On the test reading interface, the left side of the window lists all the test file names saved by the current instrument; On the right is the selection of operation commands for saving files; The upper right corner shows the current file count stored by the instrument, which includes the index of the selected file and the total number of files currently stored.

The command buttons in the file reading form include

1) Previous Page "flips up the content in the file display list

2) Next Page "flips down the content in the file display list

3) Delete all files "Delete all test files currently stored in the instrument

4) Delete file "to delete the currently selected file

5) Cancel to exit the file reading form

6) Read the currently selected file, and the instrument enters the "View Historical Results Interface",

4.2.4 Instrument settings

The instrument settings button is used to set the operating parameters of the instrument. Clicking the instrument settings button will load the window shown in Figure 4.3.

The system operating parameters in the instrument settings interface will only be reflected in the test report generated by the instrument, and are not related to the process control of the experiment. The detailed definitions of each parameter are shown in Table 4.1

Table 4.1 System Operating Parameters

parameter name	meaning
Instrument ID	The factory identification number of the instrument, all instruments have an ID of *
Software ID	DSP software system version number of the instrument
operator	When generating a WORD test report, the name of the operator displayed in the report
testing unit	When generating a WORD test report, the test units displayed in the report
Test site	When generating a WORD test report, the test location displayed in the report
Report header	When generating a WORD test report, the content of the report header section
Report Footer	When generating a WORD test report, the content in the footer section of the report
Include hysteresis loop curve when generating report	After completing the CT analysis experiment, include the hysteresis loop in the generated WORD report
Using integer multiples of current in the error curve	Display only integer multiples of current once when generating error curve data

The remaining parameters are related to the control of the experimental process, but only involve the experimental process during CT testing and are not related to PT testing. Their detailed meanings are shown in Table 4.2

parameter name	meaning
Automatic evaluation settings	If set to 'disable automatic evaluation', after the CT analysis test is completed, the instrument will provide various parameter values and will not automatically determine whether the current test results meet the requirements of the selected criteria. If only the operational load is evaluated, after the CT analysis test is completed, the instrument will not only provide the values of various parameters of the test, but also automatically determine whether each indicator meets the selected standard requirements based on the current operational load connected to the CT If the evaluation of rated and operating loads is set, after the CT analysis test is completed, the instrument will not only provide the values of each parameter of the test, but also automatically judge whether each indicator meets the selected standard requirements when the CT is connected to the operating load and rated load respectively
Excitation test control	By default, the system is set to automatically obtain the saturation voltage point of the system. This parameter is used for process control during CT excitation testing, and the instrument will automatically select the appropriate test frequency based on the obtained saturation voltage. If "automatic acquisition" is selected, the instrument will automatically measure the saturation voltage of the connected CT before conducting the excitation test. Otherwise, the instrument will conduct the excitation test based on the set saturation voltage. Attention: Only set the instrument to manual setting mode when the saturation voltage of the instrument cannot be correctly obtained through "automatic acquisition" or when the saturation voltage of the transformer is greater than 8KV, as manual setting mode may result in the inability to obtain fine excitation curves
Display simplified excitation data	When selected, the excitation curve data column will display an additional 30 data points, namely the 15 data points before the inflection point and the 15 data points after the inflection point. These data points are all obtained by taking equal steps from the excitation curve, which can speed up the generation of WORD documents when displaying simplified data When not selected, the instrument displays the actual number of excitation data points obtained, usually greater than 100 points
1A/5A type transformer judgment threshold	This parameter is applicable to the automatic nameplate inference working mode. When the user selects automatic nameplate inference and the secondary rated current of the transformer is unknown, the instrument uses this threshold to determine the type of transformer. If the coil resistance is less than this threshold, it is considered a 5A transformer, otherwise it is a 1A transformer
Measurement and protection type judgment threshold of 1A transformer	This parameter is applicable to the automatic inference mode of the nameplate. When the user selects automatic inference of the nameplate and the transformer level is unknown, the instrument uses this threshold to determine the protection and measurement type of the 1A transformer. If the saturation voltage is less than this threshold, it is considered to be measuring the 1A transformer. Otherwise, it is considered to be protecting the 1A transformer
Measurement and protection type judgment threshold of 5A transformer	This parameter is applicable to the automatic nameplate inference working mode. When the user selects automatic nameplate inference and the transformer level is unknown, the instrument uses this threshold to determine the protection and measurement type of the 5A transformer. If the saturation voltage is less than this threshold, it is considered to be measuring the 5A transformer. Otherwise, it is considered to be protecting the 5A transformer
Excitation data search criteria	Set to search for current through voltage In the excitation curve data column, input the excitation voltage value and the instrument will automatically search for the corresponding excitation current value When searching for voltage through current In the excitation curve data column, input the excitation current value and the instrument will automatically search for the corresponding excitation voltage value

4.2.5 Language selection

Supports both Chinese and English languages, this button is used for selecting and switching system languages. After clicking this button, the window shown in Figure 4.4 is loaded. After selecting Simplified Chinese, the working language of the instrument will be Chinese, while selecting English will change the working language of the instrument to English

4.2.6 CT parameter settings

The transformer setting button is used to set the parameters of the CT nameplate being tested and the process control parameters for CT analysis tests and transformation ratio tests. After clicking this button, the window shown in Figure 4.5 is loaded. For detailed definitions of each parameter in this form, please refer to Section 5.2 Parameter Settings

4.2.7 Data Export

The data export button is used to export saved experimental data, WORD reports, and other files on the instrument. After clicking this button, the form shown in Figure 4.6 is loaded.

The list box on the left displays the current list of files stored on the instrument. By selecting different file types from the drop-down menu, the corresponding files will be displayed in the list box on the left. The file types include "*. CTA" format data files, WORD test report files, and Jpg image files. The file index and total file counter display the total number of files of the current type stored in the instrument and the selected file index. Multiple files can be selected simultaneously by clicking with the mouse, and the selected files will be displayed with a blue background color.

The operation command buttons in the data export form include:

1) Previous Page "flips up the content in the file display list

2) Next Page "flips down the content in the file display list

3) Clearing memory "refers to deleting all files in the" test data "directory of the USB drive inserted into the instrument

4) Delete all files "Delete all test files currently stored in the instrument

5) Delete file "to delete the currently selected file stored in the instrument

6) Export all files ", export all experimental files in the current left window to a USB drive. If "*. CTA" is currently selected, all "*. CTA" files in the left list box will be exported to the "Test Data Instrument Test Data" file directory on the USB drive. If ". Doc" files are currently selected, all "*. Doc" files in the left list box will be exported to the "Test Data WORD Test Report" directory on the USB drive. If the current selection is a ". JPG" file, all "*. JPG" files in the left list box will be exported to the "Experimental Data Jpg Graphic Files" directory on the USB drive

7) Export file "to export the currently selected file to the corresponding directory on the USB drive.

8) Cancel to exit the file export form

4.2.8 Use of Help

This button can open the usage help document of the instrument. The usage help document is stored in the instrument in the file format of "*. Pdf". When the user clicks this button, the usage help document will be opened.

4.3 Main workspace

All areas located in the middle of the software are the main workspace of the software. When the instrument is in different test states, the content of the main workspace will be switched. For example, when the instrument is in the "waiting for new test state", the main workspace of the instrument will display a test selection button, as shown in Figure 4.1. When the instrument is in "view results" or "view historical results" and the current display mode is selected as excitation curve, the instrument will display as shown in Figure 4.7

4.4 Instrument operation status information column

The information displayed in the instrument status information column includes:

1) The current operating status of the instrument, such as "waiting for new experiment", "waiting for experiment", "viewing results", "viewing historical results", "running", "waiting to view historical results", etc.

2) In addition to the operating status of the instrument, there is also an identification of the communication between the internal industrial computer and DSP of the instrument. If the communication between DSP and industrial computer is successful, the instrument will display online in the status information bar, otherwise the instrument will display offline status.

3) The current experimental project includes the name of the selected experimental project, such as "CT analysis", "measurement of differential angle", etc

4) System date and time. When the instrument is in an online non operational state, this column will display the current system date, system time, and ambient temperature at the current panel

5) Environmental temperature. The instrument updates the ambient temperature measurement every 2 minutes, and the measured ambient temperature will be used to calculate the reference coil resistance at 75 degrees Celsius

4.5 Test Control Bar

The experimental control bar has buttons for "experimental parameter settings" and "start experiment". When the instrument is in a waiting state for the experiment, clicking the "experimental parameter settings" button will display the corresponding experimental parameter settings window. In these windows, users can set the control parameters for the current experiment.

The "Start Experiment" button is used to start and stop the current experiment. When the user clicks the "Start Experiment" button from the "Wait for Experiment" or "View Results" state, the instrument enters the "Run" state, and the corresponding experiment will be started. The identification of this button will change to "Stop Experiment". After clicking the button again or the experiment is automatically completed, the instrument enters the "View Results" state, and the corresponding result parameters will be automatically calculated and displayed.

Attention: When the instrument is in "View Historical Results" mode, if you need to run a test, you must first click on "New Test" to enter the "Waiting Test Interface", and then follow the process of "Waiting for New Test" ->"Waiting Test" ->"Run" ->"View Results" to complete the test project.

4.6 Startup and shutdown of instruments

After turning on the power of the instrument panel, the software system of the instrument is automatically loaded, and the instrument enters the "waiting for new experiment" state, completing the startup process.

If you want to turn off the instrument, please first use the "Close System" button on the software interface to turn off the instrument. Wait for the instrument display screen to prompt 'It is safe to shutdown now' before cutting off the power to the instrument.

Attention: In case of emergency, please directly cut off the power supply of the instrument

Chapter 5 Experimental Operation

5.1 General process of experimental operation

As described in Chapter 4, the software operation of the instrument can be divided into six states: "waiting for new experiment", "waiting for experiment", "viewing results", "running", "viewing historical results", and "waiting to view historical results". The common processes for software operation are as follows:

1) After the instrument is turned on, enter "Waiting for New Test"

Waiting for New Experiment "->" Waiting for Experiment "->" Run "->" View Results "

The description of this process is that the instrument enters the "waiting to create a new experiment" state for the first time. In this state, the user selects the experiment to be conducted, such as CT analysis, and then sets the various parameters of the CT analysis experiment. The instrument then enters the "waiting experiment" state, and the user clicks the "start experiment button" to start the experiment. After the experiment is completed, it automatically stops, and the instrument automatically calculates various parameters and enters the "view results" state.

2) Start another experiment from the 'View Results' status

View Results ->Wait for New Experiment ->Wait for Experiment ->Run ->View Results

If the instrument needs to perform another test item after completing one experiment, this process should be followed. Click the "New Experiment" button in the "View Results" state, and the instrument will enter the "Waiting for New Experiment" state. The following process is described in the first item*

Repeat the current experiment

View Results ->Run ->View Results

After completing an experiment and repeating it with the same parameters, simply click the "Start Experiment" button in the "View Results" state.

5.2 CT analysis

5.2.1 CT analysis test parameter settings

The parameter setting interface for the CT analysis test project is shown in Figure 5.1. The parameter setting interface for CT analysis test and differential angle difference test is *, and all required parameter items for differential angle difference test also need to be set in CT analysis.

The parameter settings for CT analysis are divided into two parts: parameters related to the transformer level and parameters unrelated to the transformer level. Table 5.1 describes various parameters that are independent of the transformer level. The test parameters listed in Tables 5.2 to 5.8 are additional parameters that need to be configured for different levels of transformers.

Attention: When the saturation voltage of the transformer is greater than 8KV, please select manual excitation test saturation voltage setting on the system parameter setting interface. For details, please refer to the system parameter settings

5.2.2 CT analysis test process

When conducting CT analysis experiments, users need to follow the following steps:

1) On the premise of following safety rules, connect the instrument and transformer according to the wiring diagram analyzed by CT

2) Select the "CT Analysis" experimental project on the software

3) Complete various test parameter settings for transformers

4) Start the experiment and wait for its completion

5) View Results

Attention: For transformers with high saturation voltage, the instrument will detect the excitation characteristics of the transformer at a very low frequency (possibly as low as 0.25Hz), so the time required to complete the entire test at this time may be longer (up to half an hour). Please be patient. It is strictly prohibited to disconnect the test line during the testing process

When conducting CT analysis experiments, the instrument will complete the entire experiment according to the following process:

Coil resistance detection ->primary demagnetization ->secondary demagnetization ->fine voltage regulation and measurement of differential angle difference ->coarse adjustment and measurement of differential angle difference ->measurement of transformer excitation curve

1) If the user selects a non automatic saturation voltage acquisition mode, a demagnetization process will be skipped

2) If the saturation voltage of the transformer is low, the process of coarse adjustment measurement of the differential angle difference will be skipped

During the experiment, the lower left corner will indicate the current power output and test operation status of the instrument.

In the parameter setting interface, if "Quick Test" is selected, the number of recording points of the instrument is relatively small and the voltage step value is large during the boosting process. Therefore, for transformers with high remanence coefficient and low saturation voltage (<250V), the excitation curve will appear uneven. At this time, the standard test is selected.

When selecting standard tests, there are more data points recorded by the instrument, excitation curves, and calculation parameters. However, when selecting standard tests, the test duration is more than twice that of rapid tests.

Figure 5.1 CT analysis test parameter settings

parameter name	Parameter Description
Do you speculate on the information	Used for CT analysis and variable ratio test project control. If the input is a known nameplate, the instrument will not automatically infer the nameplate information. If the automatic nameplate guessing is selected, the instrument will automatically infer the "rated primary current", "rated secondary current", and "transformer level" based on the missing information
manufacturer	This project is only used for identifying transformers when generating WORD test reports and is not related to the test process
Transformer model	This project is only used for identifying transformers when generating WORD test reports and is not related to the test process
Transformer number	This project is only used to identify transformers when generating WORD test reports and to save the file names formed during the test, and is not related to the test process
Rated primary current	Set the rated primary current value of the transformer. If the automatic inference nameplate is selected and the rated primary current is set to unknown, the instrument will automatically guess the rated primary current value
Rated secondary current	Set the rated secondary current value of the transformer. If the automatic inference nameplate is selected and the rated secondary current is set to unknown, the instrument will automatically guess the rated secondary current value
rated frequency	The rated frequency option is used for controlling the differential angle measurement test project. If 50Hz is selected, the instrument will measure the differential angle difference of the transformer at a frequency of 50Hz. If 60Hz is selected, the instrument will measure the differential angle difference and angle difference of the transformer at a frequency of 60Hz
Error curve calculation point	For the protection type transformer of IEC60044-1, the instrument will calculate the error curve at this point
Selection of testing standards	By selecting different testing standards, the instrument will obtain different test result parameters, and the definition of the same result parameters may also be different, such as inflection point voltage and inflection point current
Transformer grade	After selecting the testing standard, choose the level definition of the transformer under this standard.
Secondary load	The calculation parameters of CT analysis and differential angle test are related to the connected load, so different load values will result in different test parameters. Therefore, the calculation results of the instrument will provide two types of results under the rated load conditions and operating load conditions of the transformer. Rated load: refers to the maximum allowable load value indicated on the nameplate of the transformer Operating load: It is the measured value of the current load connected to the transformer Load range: 0~100.00, power factor range: 0~1.00
75 degree Celsius coil resistance	The coil resistance value of the transformer identified on the nameplate at 75 degrees Celsius, with a resistance range of 0~100.000

Figure 5.2 Parameter definitions of IEC60044-1/GB1208 metering current transformers

name	Parameter Description
Instrument security factor FS	The protection factor of the instrument, which affects the results of automatic evaluation, ranges from 1 to 300
Extended current calculation point Ext	Additional calculation of the current point with differential angle difference is required, and this calculation result is presented in the differential angle difference test results, with a parameter range of 0% to 400%

Figure 5.3 Parameter Definition of 5P/10P/5PR/10PR Current Transformers in IEC60044-1/GB1208

name	Parameter Description
Accurate limit coefficient ALF	The accurate limit coefficient of, this parameter affects the results of automatic evaluation, parameter range: 1~300
Large short-circuit current	Possible large short-circuit current in the circuit where the primary side of the transformer is located

Figure 5.4 Parameter Definition of PX Type Current Transformers in IEC60044-1/GB1208

name	Parameter Description
Accurate limit coefficient ALF	The accurate limit coefficient of, this parameter affects the results of automatic evaluation, parameter range: 1~300
area coefficient	The coefficient of increase in area, which affects the results of automatic evaluation, parameter range: 1~300
Accurately limit voltage	The accurate voltage limit indicated on the nameplate affects the automatic evaluation results, with a parameter range of 0 to 10000.00
Accurately limit current	Accurately limit the current, this parameter affects the automatic evaluation results, with a parameter range of 0~9.9999A

Figure 5.5 Parameter Setting of IEC60044-6 TPS Transformer

name	Parameter Description
Symmetrical short-circuit current coefficient Kssc	The symmetrical short-circuit current coefficient Kssc, which affects the calculation and automatic evaluation of the result parameters, ranges from 1 to 300
Transient area coefficient Ktd	The transient area coefficient Ktd of the parameter affects the calculation and automatic evaluation results, with a parameter range of 1~300
One time constant Tp	One time constant of, this parameter affects the calculation of result parameters and automatic evaluation results, parameter range: 0~10000ms
Accurately limit the voltage Val	The accurate voltage limit indicated on the nameplate affects the calculation and automatic evaluation of the result parameters. The parameter range is 0~10000V
Accurately limit the current Ial	The accurate current limit indicated on the nameplate affects the calculation and automatic evaluation of the result parameters. The parameter range is 0~9.9999A

Figure 5.6 Parameter Setting of IEC60044-6 TPX/TPY Transformer

name	Parameter Description
Symmetrical short-circuit current coefficient Kssc	The symmetrical short-circuit current coefficient Kssc, which affects the calculation and automatic evaluation of the result parameters, ranges from 1 to 300
Transient area coefficient Ktd	The transient area coefficient Ktd of the parameter affects the calculation and automatic evaluation results, with a parameter range of 1~300
One time constant Tp	One time constant of, this parameter affects the calculation of result parameters and automatic evaluation results, parameter range: 0~10000ms
Quadratic time constant Ts	The quadratic time constant of the parameter affects the results of automatic evaluation, with a parameter range of 0~100000ms
Work cycle selection	Choose work cycle C-O or C-O-C-O, this parameter affects the calculation of result parameters and automatic evaluation results
*Secondary current time limit t1	The accurate limit of cannot be reached within t-al1 time, ranging from 0 to 10000ms. This parameter affects the calculation of result parameters and automatic evaluation results
Second current time limit t2	The accurate limit of cannot be reached within the time of t-al2, with a range of 0-10000ms. This parameter affects the calculation of result parameters and automatic evaluation results
*The allowable time t-al1 for the accurate limit of the second working cycle	Range: 0-10000ms, this parameter affects the calculation of result parameters and automatic evaluation results
The allowable time t-al2 for the accurate limit of the second working cycle	Range: 0-5000ms, this parameter affects the calculation of result parameters and automatic evaluation results
*Delay tfr for secondary opening and reclosing	Range: 0-5000ms, this parameter affects the calculation of result parameters and automatic evaluation results

Figure 5.7 Parameter Setting of IEC60044-6 TPZ Transformer

name	Parameter Description
Symmetrical short-circuit current coefficient Kssc	The symmetrical short-circuit current coefficient Kssc, which affects the calculation and automatic evaluation of the result parameters, ranges from 1 to 300
Transient area coefficient Ktd	The transient area coefficient Ktd of the parameter affects the calculation and automatic evaluation results, with a parameter range of 1~300
One time constant Tp	One time constant of, this parameter affects the calculation of result parameters and automatic evaluation results, parameter range: 0~10000ms
Quadratic time constant Ts	The quadratic time constant of the parameter affects the results of automatic evaluation, with a parameter range of 0~100000ms

Figure 5.8 C57.13 Transformer Parameter Settings

name	Parameter Description
Rated thermal current coefficient RF	The rated secondary thermal current coefficient indicated on the nameplate, if this parameter is not 0, will be calculated by multiplying the rated current by this coefficient to obtain the ratio and angle difference of the measurement point. This parameter affects the calculation and automatic evaluation of the results. Parameter range: 0~10.00
Rated secondary terminal voltage VB	The rated secondary voltage indicated on the nameplate affects the parameter calculation and automatic evaluation results. Parameter range: 0~10000.0V

5.2.3 CT analysis test results

After the CT analysis test is completed, the excitation curve shown in Figure 4.7 will be displayed first. By using the test result item switching button in the figure, the current test result content can be changed. The instructions for each button are as follows:

1 Hysteresis Loop and Data

After clicking the hysteresis loop button, the saturation hysteresis loop of the tested transformer core will be displayed on the screen as shown in Figure 5.2.1. The curve is the saturation hysteresis loop curve obtained by the tested transformer at a certain test frequency, which is displayed on the left side of the interface. The horizontal axis of the curve is the instantaneous current, and the vertical axis is the corresponding magnetic flux (in Weber) at that current. The hysteresis loop consists of an upward curve and a downward curve. Clicking "Start Data Analysis" can obtain the upward curve data and downward curve data corresponding to a certain current point on the curve. Clicking on the hysteresis loop data can view the current value and magnetic flux value of all measurement points

2. Magnetization curve data

After clicking on the magnetization curve data, the interface shown in Figure 5.2 will be loaded. The magnetization data points corresponding to the magnetization curve will be displayed in this window. Drag the slider in the list box or press the directional keys on the keyboard to browse all the magnetization curve data. At the bottom of the interface are the automatically calculated inflection point voltage and inflection point current of the magnetization curve. The magnetization curve display interface also supports excitation current query function. As long as a value that does not exceed the high excitation voltage is entered in the excitation voltage text box, the analyzer will automatically calculate and display its corresponding excitation current value.

3 magnetization curve

The interface of the magnetization curve is shown in Figure 4.7, which displays the automatically calculated inflection point voltage, inflection point current, and magnetization curve graph. By selecting the "inflection point display" checkbox, the position of the inflection point on the magnetization curve can be displayed and hidden.

After selecting "Start Data Analysis" on the magnetization curve display interface, the magnetization current and voltage values corresponding to the current position can be obtained through the positioning line. The position of the positioning line can be changed by "<<left shift", ">>right shift", and "mouse click". Mouse click "refers to clicking on the magnetization curve display area with the mouse or touch screen after" starting data analysis ", and the positioning line will move to the X coordinate at the clicked location.

By clicking on the curve comparison, you can also compare the current curve with the stored historical curve. The display interface is shown in Figure 5.3. The curve comparison function can be used to compare the measurement curves of the same transformer at different times, as well as to compare the excitation characteristic curves of three-phase transformers. The definition of each button in the curve comparison window is as follows:

Read reference curve 1

Read 1 reference excitation curve from the stored historical data and compare it with the current curve

Read reference curve 2

Read 1 reference excitation curve from the stored historical data and compare it with the current curve

Clear reference curve

Clear all reference curves in the current comparison window

Copy image

Copy the current comparison curve graphic window into a JPG file and save it. The saved JPG file can be exported through a USB drive

exit

Close the curve comparison window

X coordinate setting

Adjust the X-coordinate range of the curve comparison graphic window. This parameter can change the X-axis scaling ratio of the graphic

Y coordinate setting

Adjust the Y-axis range of the curve comparison graphic window. This parameter can change the Y-axis scaling ratio of the graphic

data analysis

After clicking to start data analysis, a positioning line will appear in the oscilloscope window, and the Y coordinate value corresponding to the X-axis position can be read by moving the positioning line. You can change the position of the positioning line by "moving left", "moving right" or clicking the mouse

4 Error Curve Data and Error Curve

When selecting the protection type of IEC60044-1 transformer, the CT analysis test will also draw the error curve of the transformer and list the error curve data. The error display method is shown in Figure 5.4. The error curve data is shown in Figure 5.2, but there is no display of the inflection point voltage and inflection point current items when displaying the error curve data. The curve comparison function in the error curve window and the curve comparison function in the magnetization curve window * are detailed in the curve comparison explanation of the magnetization curve.

Test results of 5-point differential angle difference

After the CT analysis test is completed, the ratio difference, angle difference, turns ratio, turns ratio error, and polarity of the transformer will also be displayed. Clicking on "Ratio Difference and Angle Difference" will display the test results of ratio difference and angle difference as shown in Figure 5.5.

In the display interface of the comparison angle difference results, the definitions of each parameter are shown in Table 5.9.

Table 5.9 Comparison and Angle Difference Display of CT Analysis Test

parameter	Parameter Description
Rated primary current	The transformer parameters set before starting the test are used for calculating the turns ratio error
Rated secondary current	The transformer parameters set before starting the test are used for calculating the turns ratio error
standard	The parameters of the transformer set before starting the test, and the differential angle difference detection are carried out according to this standard
frequency	The parameters of the transformer set before starting the test, and the differential angle difference result are detected at this frequency
turns ratio	Measured turns ratio of transformer
Turn ratio error	The calculation formula for the error between the measured turns ratio and the rated current ratio is: (measured turns ratio - rated current ratio)/rated current ratio. The rated current ratio is: (rated primary current/rated secondary current)
polarity	The current wiring polarity of the measured current transformer is displayed as the same polarity (i.e. - polarity) or opposite polarity (i.e.+polarity)
rated load	The transformer parameters set before starting the test are used for calculating the differential angle difference
Rated power factor	The transformer parameters set before starting the test are used for calculating the differential angle difference
Rated load ratio difference angle	Ratio difference and angle difference data when the transformer is connected to the rated load
Operating load	The transformer parameters set before starting the test are used for calculating the differential angle difference
Operating power factor	The transformer parameters set before starting the test are used for calculating the differential angle difference
Operating load ratio difference angle difference	Ratio and angle difference data when the transformer is connected to the operating load

6-coil resistance

After the CT analysis experiment is completed, clicking the coil resistance button will load the coil resistance measurement parameter window shown in Figure 5.6.

7 Error Curve Data and Error Curve

When selecting the protection type of IEC60044-1 transformer, the CT analysis test will also draw the error curve of the transformer and list the error curve data. The error curve display method is shown in Figure 5.4. The error curve data display is shown in Figure 5.2, but there is no inflection point voltage and inflection point current item displayed when displaying the error curve data.

Test results of 8-ratio differential angle difference

After the CT analysis test is completed, the ratio difference, angle difference, turns ratio, turns ratio error, and polarity of the transformer will also be displayed. Clicking on "Ratio Difference and Angle Difference" will display the test results of ratio difference and angle difference as shown in Figure 5.5.

The definitions of each item in the display interface of the measured parameters of the coil resistance are shown in Table 5.10.

Figure 5.10 Explanation of Coil Resistance Interface Parameters

name	Parameter Description
test current	The actual current value loaded onto the secondary winding during testing
test temperature	Actual ambient temperature value during testing
test voltage	The voltage value detected on the secondary winding during testing
coil resistance	The coil resistance value detected by the current ambient temperature
reference temperature	The temperature that needs to be converted according to the standard
coil resistance	The coil resistance value calculated according to the formula, where Kcopper uses the temperature coefficient of resistance of copper material

9 Excitation Parameters and Testing Evaluation

Click the "Excitation Parameters and Test Evaluation" result button in the CT analysis test result display interface, and the excitation parameters and automatic evaluation results measured based on the excitation characteristics will be displayed in the form of Figure 5.7. The excitation parameter calculation items vary depending on the selected transformer level. For detailed parameter explanations, please refer to Chapter 6, Automatic Evaluation and nameplate inference.

Below the interface in Figure 5.7 is the automatic evaluation result, which includes individual evaluation items, evaluation criteria, and final evaluation results. If the individual evaluation passes, the next column of the list will display as qualified; otherwise, it will display as unqualified and the color of the item will turn red. For detailed evaluation instructions and evaluation conditions, please refer to "Chapter 6: Automatic Evaluation and Nameplate Speculation".

5.3 CT Differential Angle Measurement

5.3.1 Parameter Setting for Differential Angle Measurement Test

The parameter setting interface for the differential angle measurement test and the CT analysis parameter setting interface and setting items *, please refer to section 5.2.1 CT analysis parameter setting for details

5.3.2 Test Procedure for Differential Angle Difference

When conducting the differential angle measurement test, the steps of the test are as follows: CT analysis *. For details, please refer to section 5.2.2 CT analysis test process. The typical experimental procedure for measuring CT differential angle difference is as follows“

Coil resistance detection ->primary demagnetization ->secondary demagnetization ->fine voltage adjustment measurement of differential angle difference ->coarse adjustment measurement of differential angle difference

1) If the user selects a non automatic saturation voltage acquisition mode, a demagnetization process will be skipped

2) If the saturation voltage of the transformer is low, the process of coarse adjustment measurement of the differential angle difference will be skipped

During the experiment, the lower left corner will indicate the current power output and test operation status of the instrument.

5.3.3 Display of Differential Angle Test Results

The display of the results of the differential angle difference test and the CT analysis test is * *. For details, please refer to 5.2.3 CT analysis test result display

5.4 CT coil resistance measurement

The CT coil resistance measurement test only requires setting the transformer number. After selecting the coil resistance measurement, the instrument provides a reference diagram for the test wiring. Start the test, the instrument outputs 0.5A DC current to charge the coil. When the coil resistance value stabilizes, the test automatically stops and records the coil resistance value and ambient temperature value at the stop time (the instrument panel is equipped with a temperature sensor to measure the current ambient temperature).

After the experiment, the instrument will automatically calculate the reference resistance value at a temperature of 75 degrees Celsius.

The display method of the results after the experiment is the same as the coil resistance display page in section 5.2.3.

5.5 CT polarity examination

CT polarity test only requires setting the transformer number. After selecting the polarity check test, the instrument provides a reference diagram for the test wiring. After starting the test, the instrument outputs an AC sine voltage to the CT secondary winding and measures the voltage of the CT primary winding. When the CT primary winding voltage exceeds the measurement threshold or the CT secondary voltage output reaches a high voltage, the instrument calculates the CT polarity at this time. The instrument determines the polarity of the CT being tested according to the following criteria:

When the phase angle difference between the primary voltage and the secondary voltage is greater than -90 degrees, the calculated result is of the same polarity (- polarity), otherwise it is of the opposite polarity (+polarity)

After the polarity check test is completed, the test results are shown in Figure 5.8.

5.6 CT secondary load measurement

5.6.1 CT secondary load measurement parameter settings

The test parameter setting items for secondary load measurement include transformer number, test current, test frequency. After selecting the secondary load measurement, the parameter setting window shown in Figure 5.9 will be loaded. After starting the secondary load test, the instrument will output a constant sine current to the CT secondary load circuit based on the selected parameters.

In the secondary load parameter setting interface shown in Figure 5.9, the meanings of the three test parameters are:

1> CT rated secondary current

This parameter does not affect the test process and is only used to calculate the load value of the secondary circuit. For example, if the impedance of the secondary circuit is measured as 2ohm, and the rated secondary current is selected as 1A, the corresponding secondary load is 2VA. If the rated secondary current is selected as 5A, the corresponding secondary load is 50VA

2> Rated frequency

This parameter is used to control the frequency value of the output current. If 50Hz is selected, the frequency of the output current is 50Hz; otherwise, the frequency of the output current is 60Hz

3> Transformer number: Name of the component that stores the test file

5.6.2 CT Secondary Load Measurement Test Procedure

The secondary load measurement of the instrument is divided into two levels, and the output current value (RMS) and corresponding range of the two levels are:

1) The test current is 0.5A (RMS), and the measurement range is 0-80ohm

2) The test current is 0.25A (RMS), and the measurement range is 0-160ohm

After the experiment is started, the instrument first outputs a test current of 0.5A (RMS). If it is found that the measured load exceeds the range, the instrument automatically adjusts the output current value to 0.25A (RMS) and measures again

5.6.3 CT secondary load measurement test results

The measurement results of CT secondary load are shown in Figure 5.10.

The definitions of various parameters on the secondary load test results page are shown in Table 5.11.

Table 5.11 Parameters of Secondary Load Test Results

name	Parameter Description
Rated secondary load	The rated secondary load value of the instrument expressed in VA or impedance form
Rated power factor	Power factor value of rated secondary load
test current	Actual test current value expressed as effective value
test voltage	Effective value of voltage loaded on the secondary circuit
test frequency	Effective value of current loaded on the secondary circuit
Secondary load	The measured secondary load value is expressed in VA form, which is: rated secondary current * rated secondary current * measured secondary impedance
power factor	Measured power factor value of the secondary circuit
Secondary impedance	Measure the impedance value of the secondary circuit

5.7 PT coil resistance measurement

After selecting the PT coil resistance measurement, the instrument provides a reference diagram for the test wiring and a test current selection interface as shown in Figure 5.11.

Start the test, the instrument outputs 0.5A (or 0.05A, 0.005A) DC current to charge the coil. When the coil resistance value stabilizes, the test automatically stops, and the coil resistance value and ambient temperature value at the stop time are recorded (the instrument panel is equipped with a temperature sensor to measure the current ambient temperature). After the completion of the experiment, the result display method is the same as the coil resistance display page in section 5.2.3, but the PT coil resistance test did not calculate the reference resistance value at 75 degrees Celsius.

For electromagnetic PT, the resistance of both the primary and secondary coils can be tested through this project, while for CVT type voltage transformers, only the resistance value of the secondary coil can be tested.

5.8 PT polarity check

The PT polarity test only requires setting the number of the transformer. After selecting the polarity check test, the instrument provides a reference diagram for the test wiring. After starting the test, the instrument outputs an AC sine voltage to the PT primary winding and measures the voltage of the PT secondary winding. When the PT secondary winding voltage exceeds the measurement threshold or the PT primary voltage outputs to a high voltage, the instrument calculates the PT polarity at this time. The instrument determines the polarity of the tested PT according to the following standards:

When the phase angle difference between the primary voltage and the secondary voltage is greater than -90 degrees, the calculated result is of the same polarity (- polarity), otherwise it is of the opposite polarity (+polarity)

After the polarity check test is completed, the test results are consistent with Figure 5.8 *.

5.9 PT secondary load measurement

5.9.1 PT secondary load measurement parameter settings

The test parameter setting items for PT secondary load measurement include transformer number, test voltage, test frequency. After selecting the secondary load measurement, the parameter setting window shown in Figure 5.12 will be loaded. After starting the secondary load test, the instrument will output a constant sine voltage to the PT secondary load circuit based on the selected parameters.

In the secondary load parameter setting interface shown in Figure 5.12, the meanings of the three test parameters are:

Transformer number

Used to form the file name for saving experiments

2> Rated frequency

This parameter is used to control the frequency value of the output voltage. If 50Hz is selected, the frequency of the output voltage is 50Hz; otherwise, the frequency of the output voltage is 60Hz

PT rated secondary voltage

The instrument uses this parameter to calculate the high output voltage value. After the experiment is started, the instrument outputs a voltage with an amplitude equal to the secondary rated value of the transformer to the secondary circuit. The impedance of the secondary circuit is measured at this voltage, and the load value is calculated based on the secondary rated voltage.

Secondary load=(secondary rated voltage x secondary rated voltage)/secondary circuit impedance

5.9.2 PT Secondary Load Measurement Test Procedure

After the experiment is started, the instrument first outputs a small test voltage to the secondary circuit and gradually boosts it, while checking for overload. If the output current is found to be overloaded, the instrument stops boosting, otherwise it continues to rise to the secondary rated voltage value. Measure the impedance value of the secondary circuit at high output voltage and calculate the secondary load based on the rated secondary voltage.

5.9.3 PT secondary load measurement test results

The display page of PT secondary load and CT secondary display page *, but there is no display of rated load on the PT secondary load display page, and their parameter meanings are the same. For details, please refer to section 5.6.3

5.10 PT ratio

5.10.1 PT Ratio Test Parameter Setting

The parameter setting interface for PT ratio test is shown in Figure 5.13, and the parameters that need to be set are defined in Table 5.12

Figure 5.12 PT ratio parameter setting

name	Parameter Description
manufacturer	This project is only used for identifying transformers when generating WORD test reports and is not related to the test process
Transformer model	This project is only used for identifying transformers when generating WORD test reports and is not related to the test process
Transformer number	This project is only used to identify transformers when generating WORD test reports and to save the file names formed during the test, and is not related to the test process
Rated primary voltage	Set the rated primary voltage value of the voltage transformer for calculating the rated transformation ratio
Rated secondary voltage	Set the rated secondary voltage value of the voltage transformer for calculating the rated transformation ratio. The rated secondary voltage of the transformer consists of two parts, and the actual voltage is the product of the two parts

5.10.2 PT ratio test process

When conducting PT ratio test, the test process is as follows:

Reverse connection judgment ->measurement of turns ratio and polarity

5.10.3 PT ratio result display

The PT ratio test results show the measured resistance value, turns ratio, and connection polarity of the primary coil.

5.11 PT excitation test

5.11.1 PT excitation test parameter setting

The parameter setting interface for PT excitation test is shown in Figure 5.14, and the parameters that need to be set are defined in Table 5.13

Figure 5.13 PT ratio parameter setting

name	Parameter Description
Transformer number	This project is only used to identify transformers when generating WORD test reports and to save the file names formed during the test, and is not related to the test process
Rated primary voltage	Set the rated primary voltage value of the voltage transformer. This project is only used to identify and save the transformer when generating WORD test reports, and is not related to the test process
Rated secondary voltage	Set the rated secondary voltage value of the voltage transformer to control the transformer voltage boosting process. During the test, the instrument voltage boosting will not exceed 1.2 times the rated secondary voltage of the transformer. After the test is completed, the instrument calculates the excitation loss at each point based on this value. The rated secondary voltage consists of two parts: an input text box and a multiple checkbox.
test frequency	Select the rated operating frequency of the transformer
DC resistance once	The measured value of the DC resistance of the PT primary winding is used to calculate the PT ratio difference and angle difference value
Secondary load	The impedance and power factor of the secondary load connected to PT are used to calculate the PT ratio difference and angle difference
PT turns ratio	The measured values of PT turns ratio and PT transformation ratio test are used to calculate the PT ratio difference and angle difference

5.11.2 Display of PT excitation test results

The PT excitation test results include the PT excitation curve, PT excitation curve data, PT secondary coil resistance, PT secondary excitation current corresponding to 20%, 50%, 80%, 100%, and 120% rated secondary voltage positions, and the ratio and angle differences at 80%, 100%, and 120% rated voltage positions

5.12 Generate Test Report

The software of CTPT analyzer can automatically generate test reports in WORD format, and the test reports are in MS WORD2003 format Save in DOC format. After the experiment is completed, click the generate button on the "View Results" or "View History Results" interface, and the instrument will automatically generate a test report for the corresponding experiment item. Figure 5.15 shows the homepage of the CT analysis test report.

Figure 5.15: First page of CT analysis test report

Chapter 6: Automatic Evaluation and Nameplate Speculation

6.1 Automatic evaluation

6.1.1 Definition of Automatic Evaluation

Automatic evaluation refers to comparing the measured parameters with the currently selected standard values. If all the measured parameters meet the standard requirements, the transformer detection is qualified. Otherwise, the transformer detection is unqualified. Due to the fact that many parameters of the transformer are related to the load to which it is connected, there are two automatic evaluation options for the instrument: "only for operating load evaluation" and "for rated and operating load evaluation".

When selecting 'Only for operational load assessment', the instrument only compares the parameters calculated under operational load conditions with the values specified in the standard. If "Evaluation of rated load and operating load" is selected, the instrument will compare the parameters calculated under both rated load and operating load conditions with the standard specified values. Only when the parameters calculated under both conditions are qualified, will the transformer detection display as qualified

Note: Automatic evaluation and nameplate inference are only applicable to CT analysis projects and are not valid for other experimental projects

6.1.2 Automatic evaluation of projects and qualification criteria

For different levels of transformers, the automatic evaluation items are different. Detailed evaluation items and qualification conditions are shown in Table 6.1 to Table 6.5

Table 6.1 Evaluation Items and Qualification Conditions for IEC60044-1 Metering Current Transformers

Transformer grade	evaluation project	Evaluate the eligibility criteria
0.1 level	1) Instrument security factor FS 2) The current ratio difference angle at 25%, 100% rated load and operating load conditions for secondary currents of 5%, 20%, 50%, 100%, and 120% rated current	1) Tested FS<=FS rated 2) 5% rated secondary current ratio difference<=0.4% 20% rated secondary current ratio difference<=0.2% 100120% rated secondary current ratio difference<=0.1% 5% rated secondary current angle difference<=15 minutes 20% rated secondary current ratio difference<=8 points 100120% rated secondary current ratio difference<=5 points
Level 0.2	1) Instrument security factor FS 2) Current ratio difference and angle difference of secondary current at 5%, 20%, 50%, 100%, and 120% rated current under 25%, 100% rated load and operating load conditions	1) Tested FS<=FS rated 2) 5% rated secondary current ratio difference<=0.75% 20% rated secondary current ratio difference<=0.35% 100120% rated secondary current ratio difference<=0.2% 5% rated secondary current angle difference<=30 minutes 20% rated secondary current ratio difference<=15 minutes 100120% rated secondary current ratio difference<=10 points
0.2S level	1) Instrument security factor FS 2) Current ratio difference and angle difference of secondary current at 1%, 5%, 20%, 50%, 100%, and 120% rated current under 25%, 100% rated load and operating load conditions	1) Tested FS<=FS rated 2) 1% rated secondary current ratio difference<=0.75% 5% rated secondary current ratio difference<=0.35% 20100120% rated secondary current ratio difference<=0.2% 1% rated secondary current angle difference<=30 minutes 5% rated secondary current ratio difference<=15 minutes 20100120% rated secondary current ratio difference<=10 points
Level 0.5	1) Instrument security factor FS 2) Current ratio difference and angle difference of secondary current at 5%, 20%, 50%, 100%, and 120% rated current under 25%, 100% rated load and operating load conditions	1) Tested FS<=FS rated 2) 5% rated secondary current ratio difference<=1.5% 20% rated secondary current ratio difference<=0.75% 100120% rated secondary current ratio difference<=0.5% 5% rated secondary current angle difference<=90 minutes 20% rated secondary current ratio difference<=45 minutes 100120% rated secondary current ratio difference<=30 minutes
0.5S level	1) Instrument security factor FS 2) Current ratio difference and angle difference of secondary current at 1%, 5%, 20%, 50%, 100%, and 120% rated current under 25%, 100% rated load and operating load conditions	1) Tested FS<=FS rated 2) 1% rated secondary current ratio difference<=1.5% 5% rated secondary current ratio difference<=0.75% 20100120% rated secondary current ratio difference<=0.5% 1% rated secondary current angle difference<=90 minutes 5% rated secondary current ratio difference<45 minutes 20100120% rated secondary current ratio difference<30 points
Level 1.0	1) Instrument security factor FS 2) Current ratio difference and angle difference of secondary current at 5%, 20%, 50%, 100%, and 120% rated current under 25%, 100% rated load and operating load conditions	1) Tested FS<=FS rated 2) 5% rated secondary current ratio difference<=3% 20% rated secondary current ratio difference<=1.5% 100120% rated secondary current ratio difference<=1.0% 5% rated secondary current angle difference<=180 minutes 20% rated secondary current ratio difference<=90 minutes 100120% rated secondary current ratio difference<=60 minutes
Level 3.0	1) Instrument security factor FS 2) Current ratio difference at 50%, 100% rated load and operating load conditions for secondary current of 50%, and 120% rated current	1) Tested FS<=FS rated 2) 50% rated secondary current ratio difference<=3% 120% rated secondary current ratio difference<=3%
Level 5.0	1) Instrument security factor FS 2) Current ratio difference at 50%, 100% rated load and operating load conditions for secondary current of 50%, and 120% rated current	1) Tested FS<=FS rated 2) 50% rated secondary current ratio difference<=5% 120% rated secondary current ratio difference<=5%

Table 6. SEQ Chart * ARABIC 2 IEC60044-1 Evaluation Items and Qualification Conditions for Protective Current Transformers

Transformer grade	evaluation project	Evaluate the eligibility criteria
5P	Accurate limit coefficient ALF Difference at 100% rated current Angle difference at 100% rated current	Tested ALF>=rated ALF 100% rated current ratio difference<=1% 100% rated current angle difference<=60 minutes
10P	Accurate limit coefficient ALF Difference at 100% rated current	Tested ALF>=rated ALF 100% rated current ratio difference<=3%
5PR	Accurate limit coefficient ALF 2) Difference at 100% rated current 3) Angle difference at 100% rated current 4) Residual magnetism coefficient Kr	1) Tested ALF>=rated ALF 2) 100% rated current ratio difference<=1% 3) 100% rated current angle difference<=60 minutes 4）Kr<=10%
10PR	Accurate limit coefficient ALF 2) Difference at 100% rated current 3) Residual magnetism coefficient Kr	1) Tested ALF>=rated ALF 2) 100% rated current ratio difference<=3% 3）Kr<=10%
PX	turns ratio Accurately limit the voltage Ek Accurately limit the current Ie Area coefficient Kx 75 degree Celsius coil resistance	1) Turn ratio error<=0.25% 2) Ek measured value>=Ek rated value 3) Ie measured value>=Ie rated value 4) Kx measured value>=rated Kx value 5) 75 degrees Celsius measured coil resistance<=rated value

Table 6.3 Evaluation Items and Qualification Conditions for Transient Current Transformers in IEC60044-6

Transformer grade	evaluation project	Evaluate the eligibility criteria
TPS	turns ratio Accurately limit the voltage Val Accurately limit the current Ial Symmetrical short-circuit current coefficient Kssc 75 degree Celsius coil resistance	Turn ratio error<=0.25% Val measured value>=Val rated value Ial measured value<=Ial rated value K * Kssc measurement>=K * Kssc rated value 5) 75 degrees Celsius measured coil resistance<=rated value
TPX	Differential ratio at rated current Angle difference at rated current Peak instantaneous error at rated Kssc and measured Ktd Kssc * Ktd rated value and measured value 75 degree Celsius coil resistance	Difference at rated current<=0.5% Angle difference at rated current<=30 minutes Rated Kssc * measured Ktd peak instantaneous error<=10% (Kssc * Ktd) measured value>=(Kssc * Ktd) rated value 75 degrees Celsius measured coil resistance<=rated value
TPY	Differential ratio at rated current Angle difference at rated current Peak instantaneous error at rated Kssc and measured Ktd Kssc * Ktd rated value and measured value Quadratic time constant Ts Residual magnetism coefficient Kr 7) 75 degree Celsius coil resistance	Difference at rated current<=1.0% Angle difference at rated current<=60 minutes Rated Kssc * measured Ktd peak instantaneous error<=10% (Kssc * Ktd) measured value>=(Kssc * Ktd) rated value Ts actual measurement<=30% Ts rated Kr<=10% 7) 75 degrees Celsius measured coil resistance<=rated value
TPZ	Differential ratio at rated current Angle difference at rated current Kssc * Ktd rated value and measured value Quadratic time constant Ts 5) 75 degree Celsius coil resistance	Difference at rated current<=1.0% 2) Angle difference at rated current<=180 minutes 3) (Kssc * Ktd) measured value>=(Kssc * Ktd) rated value 4) Ts actual measurement<=30% Ts rated 5) 75 degrees Celsius measured coil resistance<=rated value

Table 6.4 C57.13 Automatic Evaluation Items and Conditions for Metrological Transformers

Transformer grade	Automatic evaluation project	Automatic evaluation of eligibility criteria
Level 0.3	Current ratio difference at 10%, 100%, 100% * RF rated secondary current under rated load and operating load	10% rated current ratio difference<=0.6% 100100 * RF% rated current ratio difference<=0.3%
Level 0.6	Current ratio difference at 10%, 100%, 100% * RF rated secondary current under rated load and operating load	10% rated current ratio difference<=1.2% 100100 * RF% rated current ratio difference<=0.6%
Level 1.2	Current ratio difference at 10%, 100%, 100% * RF rated secondary current under rated load and operating load	10% rated current ratio difference<=2.4% 100100 * RF% rated current ratio difference<=1.2%

Table 6.5 Automatic Evaluation Items and Conditions for C57.13 Protection Transformer

Transformer grade	Automatic evaluation project	Automatic evaluation of eligibility criteria
C	1) Comparison between Vbmax and VB rated values 2) Secondary current Isec at Vbmax 3) Ratio difference at 20 * Isn 4) Ratio difference at Vb rated value	1) Vbmax>=Vb rated value (if no Vb rated value is entered, the Vb rated value is automatically set to 20Isec rated value, and the secondary terminal voltage Vb under rated load) 2) Isec>=20 * Isec rated at Vbmax 3) 20 * Isn rated current ratio difference<=10% 4) Current ratio difference at Vb rated value<=10%
K	1) Comparison between Vbmax and VB rated values 2) Secondary current Isec at Vbmax 3) Inflection point voltage 4) Ratio difference at 20 * Isn 5) Ratio difference at Vb rated value	1) Vbmax>=Vb rated value 2) Isec>=20 * Isec rated at Vbmax 3) Turning point voltage>=70% Vb rated value 4) 20 * Isn rated current ratio difference<=10% 5) Current ratio difference at Vb rated value<=10%
T	1) Comparison between Vbmax and VB rated values 2) Secondary current Isec at Vbmax 3) Ratio difference at 20 * Isn 4) Ratio difference at Vb rated value	1) Vbmax>=Vb rated value 2) Isec>=20 * Isec rated at Vbmax 3) 20 * Isn rated current ratio difference<=10% 4) Current ratio difference at Vb rated value<=10%

6.2 Excitation parameter calculation

On the display interface of CT analysis test results, there is a page for excitation parameters and automatic evaluation. The calculation items of excitation parameters are determined by the selected test standards and transformer levels, and their corresponding relationships are shown in Table 6.6, Table 6.7, and Table 6.8.

Table 6.6 Excitation Parameter Calculation Items of IEC60044-1

parameter name	Parameter Description	IEC60044-1 Metrology Class	IEC60044-1 Protection Class
V-kn	Voltage inflection point, detailed definition is shown in Table 6.9	√	√
I-kn	Current inflection point, detailed definition is shown in Table 6.9	√	√
Me.	PX level transformer accurately limits voltage		√
Ie	PX level transformer accurately limits current		√
FS	Instrument security factor	√
ALF	Accurate limit coefficient		√
Kx	The area coefficient defined for PX level transformers		√
Ls	saturated inductor	√	√
Lu	Unsaturated inductance	√	√
Ts	Quadratic time constant	√	√
Kr	Remanence coefficient	√	√
Ktd	Transient area coefficient		√

The meanings of some of the parameters are as follows:

1) Ek is the electromotive force at the inflection point of the IEC60041 curve

2) Ie is the excitation current at the inflection point of the IEC60041 curve

3) The safety factor of FS instrument is the multiple of the rated current to the primary current when the CT error reaches 10%. This parameter is only valid for measuring transformers

4) The accurate limit coefficient refers to the multiple of the rated current to the primary current when the CT error reaches 5% or 10%

5) Kx area coefficient refers to the ratio of the measured accurate limit coefficient to the rated accurate limit coefficient

6) Ls saturation inductance refers to the equivalent inductance of the secondary coil of a transformer in saturation state, used to calculate the time constant of the secondary circuit in saturation state

7) Lu unsaturated inductance refers to the equivalent inductance of the secondary coil of a transformer in an unsaturated state, used to calculate the time constant of the secondary circuit in an unsaturated state

8) Kr refers to the remaining magnetic flux in the iron core when the excitation current of the transformer coil crosses zero

Table 6.7 Excitation Parameter Calculation Items of IEC60044-6

parameter name	Parameter Description	TPS	TPX/Y	TPZ
V-Kn	Voltage inflection point, detailed definition is shown in Table 6.9	√	√	√
I-Kn	Current inflection point, detailed definition is shown in Table 6.9	√	√	√
V-al	Accurate limiting voltage defined for TPS level transformers	√
I-al	Accurate limiting current defined for TPS level transformers	√
Kssc	Measured symmetrical short-circuit current coefficient
Error	Peak transient error at voltage Emax		√
Emax	Large electromotive force		√
Ls	saturated inductor	√	√	√
Lu	Unsaturated inductance	√	√	√
Ts	Secondary circuit time constant	√	√	√
Kr	Remanence coefficient	√	√	√
Ktd	Actual calculated transient area coefficient		√	√

The meanings of some of the parameters are as follows:

1) The electromotive force at the inflection point of the curve defined by IEC60046 for V-al

2) I-al excitation current at the inflection point of the curve defined by IEC60046

3) Multiple of the rated primary current by the large short-circuit current in the primary circuit of Kssc transformer

4) The rated maximum electromotive force of Emax transformer is determined by a large short-circuit current, coil internal resistance, and secondary load

5) Measurement error of the instantaneous value of the transformer corresponding to the rated maximum electromotive force of Eerr

Table 6.8 Excitation parameter calculation items for C57.13

parameter name	Parameter Description	C57.13 Metrology category	C57.13 Protection Class
V-kn	Voltage inflection point, detailed definition is shown in Table 6.10	√	√
I-kn	Current inflection point, detailed definition is shown in Table 6.10	√	√
FS	Instrument security factor	√
ALF	Accurate limit coefficient		√
Kx	The area coefficient defined for PX level transformers		√
Ls	saturated inductor	√	√
Lu	Unsaturated inductance	√	√
Ts	Quadratic time constant	√	√
Kr	Remanence coefficient	√	√

6.3 Definition of inflection point and magnetization curve

The definitions of the magnetization curve, inflection point voltage, and inflection point current for different testing standards are different. Detailed definitions are shown in Tables 6.9 and 6.10.

Table 6.9 Definition of magnetization curves for three testing standards

Standard Name	Horizontal axis of magnetization curve	Vertical axis of magnetization curve
IEC60044-1	Effective value of secondary terminal voltage	Effective value of excitation current
IEC60044-6	Effective value of electromotive force voltage	Peak excitation current
C57.13	Effective value of electromotive force voltage	Effective value of excitation current

Table 6.10 Definition of Turning Points

Standard Name	Definition of turning point
IEC60044-1	The point on the excitation curve where the secondary terminal voltage rises by 10%, causing the effective value of the excitation current to increase by more than 50%
IEC60044-6	The point where the electromotive force voltage rises by 10%, causing the peak excitation current to increase by more than 50%
C57.13	The ANSI45 inflection point for C57.13 refers to the point where the tangent of the x-axis is 45 degrees, while the ANSI30 inflection point for C57.13 refers to the point where the tangent of the x-axis is 30 degrees

6.4 nameplate inference logic

CT analyzerThe automatic inference function of the nameplate is used to guess partial information of the nameplate when the information is unknown. The inferred parameters include rated primary current, rated secondary current, and transformer level. The order and criteria for judging the nameplate inference are as follows:

1) If the rated secondary current is unknown, compare the current measured coil resistance with the 1A/5A threshold (see system parameter settings section). If it is less than the threshold, set the rated secondary current to 5A, otherwise set it to 1A

2) Based on the actual measured turns ratio and rated secondary current value, and comparing with the current selected standard's rules for determining the primary current value, guess the rated primary current value.

3) Speculation on the level of transformers

In order to guess the level of the transformer, the first step is to determine the type of the transformer core. The current core type is obtained based on the 1A or 5A core judgment threshold (see the system parameter setting section). If the saturation voltage is less than the threshold, it is the measured core, otherwise it is the protected core.

If the guessed iron core of the transformer is the measuring iron core, the instrument infers the transformer grade according to the following rules.

1) If IEC60044-1 is selected, the following accuracy levels will be automatically evaluated in order until they pass the evaluation. The * qualified evaluation levels are the accuracy levels of the transformer

0.1->0.2S->0.2->0.5S->0.5->1.0->3.0->5.0

2) If C57.13 is selected, the following accuracy levels will be automatically evaluated in order until they are qualified. The * qualified evaluation levels are the accuracy levels of the transformer

0.3->0.6->1.2

If the speculated iron core is a protective iron core, the instrument infers the transformer level according to the following rules

1) If IEC60044-1 is selected, the following levels will be automatically evaluated in order until they pass the evaluation. The accuracy level of the transformer is determined by * qualified evaluation levels

5PR->10PR->PX->5P->10P

2) If IEC60044-6 is selected, the following levels will be automatically evaluated in the following order until they pass the evaluation. The accuracy level of the transformer is determined by * qualified evaluation levels

TPY->TPX->TPZ->TPS

3) If C57.13 is selected, the following levels will be automatically evaluated in the following order until they pass the evaluation. The accuracy level of the transformer is determined by * qualified evaluation levels

K->C->T

Chapter 7 PC Data Analysis Software

7.1 Overview

The product CD of the analyzer contains two PC applications, the data analysis software "CTPT ANALYZER FOR PC" and the batch report production tool "CTPT ANALYZER BULK REPORTS". Both of these applications are green software that does not require installation. When using them, simply copy the file folders corresponding to the two applications to the computer's hard drive.

7.2 Data analysis software

Double click "CTPT Analyzer FOR PC" in the data analysis software of the analyzer, and the main interface of the data analysis software as shown in Figure 7.1 will appear.

The operation and interface of the PC data analysis software for the analyzer are basic to the instrument application software, with the following differences:

When reading files, PC data analysis software requires the user's file location as shown in Figure 7.2

When saving files, PC data analysis software requires the user's file storage location as shown in Figure 7.2

When reading the reference curve in the curve comparison window, the user needs to refer to the location of the file as shown in Figure 7.2

When copying images in curve comparison, the user's file storage location is required as shown in Figure 7.2

When generating WORD reports, the user file storage location is required as shown in Figure 7.2

Except for the differences listed above, all operating methods of the data analysis software and the instrument data processing software * *, please refer to the instrument data processing software instructions for detailed instructions

7.3 Batch Report Production Tool

In models with instrument versions V1.27.129 and above, the analyzer's product CD provides a WORD report batch processing application, which can generate multiple WORD report documents at once. Double click "CTPT Analyzer BULK REPORTS" in the CTPT analyzer batch report creation tool folder on the instrument product CD, and the window shown in Figure 7.3 will appear.

The buttons and controls in the window are defined as follows:

Batch generation of WORD reports

When clicking on the WORD report batch generation, enter the report configuration window as shown in Figure 7.4, where you can add and remove experimental files that require report production. The definitions of each button in the window in Figure 7.4 are as follows:

Add file

Click "Add File" to open the experimental result file addition window shown in Figure 7.5, where you can add the experimental result file to the WORD report to be generated queue.

Note: Multiple files can be selected simultaneously using the mouse in the window shown in Figure 7.5

remove file

Click to remove the file and remove the selected test result file from the WORD report to be generated queue from the queue

Note: This feature only removes the test result file from the queue and does not delete the corresponding test result file from the computer

Remove all files

Click to remove all files and clear all test result files in the WORD report to be generated queue

Note: This feature only removes the test result file from the queue and does not delete the corresponding test result file from the computer

Batch generate WORD reports

Generate WORD report at once to generate all test result files in the queue to be generated

Attention: When there are a large number of files in the queue to be generated, the generation process will take a long time, and the application software cannot respond to other control commands during this process. If it is necessary to terminate the generation process at this time, you can close the process of this application by pressing Ctrl+ALT+DEL.

cancel

Exit the WORD report batch generation configuration window

Control of the process of generating experimental reports

When generating WORD reports, include hysteresis loop curves. When this option is selected, hysteresis loop curves and data will be included in all CT analysis test result files in WORD reports. This configuration will consume a longer time to generate WORD reports, otherwise these curves and data will not appear in these generated WORD reports and the time to generate WORD reports will be shorter

When using integer current multiples in the error curve, when this option is selected, the error curve data will display the value of integer current multiples in all test result files of IEC60044-1 protection CT

Display simplified excitation data. When this option is selected, the magnetization curve displayed in the WORD report of all CT analysis test result files will be 30 points. This can shorten the time required to generate the WORD report, otherwise the displayed points will be actual measurement points and the time required to generate the WORD report will be longer.

Language Selection

Select the language environment for this application. The current version supports both Chinese and English languages

progress bar

The main interface of the application contains two progress bars indicating the status of the generation process. The progress bar located at the top of the main program is the overall progress indicator of the WORD report generation process for all test result files, while the progress bar located at the bottom of the main program is the progress indicator of the WORD report generation process for individual test result files.

Chapter 8 Attachment List

8.1 Standard configuration of CTPT analyzer

The standard configuration of CTPT analyzer is shown in Table 7.1:

name	quantity	explanation
CTPT analyzer host	1
3M dual core shielded test cable	2	CT secondary and power output connection wires, each cable has red and black banana heads at both ends, with a wire diameter greater than 1.5mm
10M dual core shielded test cable	1	CT primary connection cable, with red and black banana tips on both ends of each cable, with a wire diameter greater than 1.5mm
ground wire	1
Large testing pliers	2	2 red and 2 black
Test cold pressing	4	2 red and 2 black
test needle	4	2 red and 2 black
alligator clip	6	Three red and three black
Test short-circuit wires	1	Contains 6 connectors for short circuiting the remaining non test windings of CT secondary
PT excitation test module	1	Used for PT excitation test
5A power fuse	3
power supply cable	1
attachment package	1	Place various accessories for testing
Product CD	1	Includes product manual and data analysis software
Product User Manual	1
Product Factory Inspection Report	1
Certificate of Conformity	1

Appendix A. Principle of Low Frequency Method Testing

The IEC60044-6 standard (corresponding to the national standard GB16847-1997) claims that CT testing can be conducted at frequencies lower than the rated frequency to avoid unacceptable voltages on the windings and secondary terminals. *The requirement is to generate a magnetic flux of the same magnitude on the iron core.

The magnetic flux calculation formula given in IEC60044-6 standard:

among which,

R CT: Secondary winding resistance

U CT: Secondary winding terminal voltage

I CT: Secondary Current

0: Initial cross chain magnetic flux

PSI (t): Cross chain magnetic flux at time t

Define iron core voltage:

When the iron core voltage U C (t) is a sine signal, there are:

among which

f: For sine signal frequency

It can be seen that under the same large cross link magnetic flux PSI m, the iron core voltage is proportional to the frequency. Therefore, as long as the same amount of magnetic flux is generated on the iron core, CT testing can be carried out at a frequency lower than the rated frequency, and the required amplitude of the iron core voltage is also reduced. The terminal voltage required for secondary winding testing is also correspondingly reduced. After frequency conversion of the low-frequency test results, the CT test results at the rated frequency can be obtained.

Appendix B. Calculation of 10% Error Curve

The error of current transformers is mainly due to the presence of excitation current I0, which causes the secondary current I2 and the primary current I1 'converted to the secondary side to not only be numerically unequal, but also have different phases, resulting in errors in current transformers.

Relay protection requires that when the primary current I1 of the current transformer is equal to the large short-circuit current, the ratio difference should be less than or equal to 10%. When the ratio difference is equal to 10%, the relationship between the secondary current I2, the primary current I1 'converted to the secondary side, and the excitation current I0 satisfies the following:

If M is defined as the multiple of the primary side short-circuit current and K is the transformation ratio of the current transformer, then there is

?

among which

Z2 is the impedance of the secondary winding of the current transformer

The relationship between the induced electromotive force E0 and I0 in the secondary winding of the current transformer is described by the excitation characteristic curve.

According to the above formula, the 10% error curve described by the multiple of large short-circuit current M and the allowable large load impedance ZB can be obtained

The calculation method for the 5% error curve is the same as that for the 10% error curve, except that the error point has changed from 10% to 5%. For 5P/5PR current transformers, a 5% error curve is usually calculated, while for 10P/10PR protective current transformers, a 10% error curve is usually calculated.