Fully automatic and functional transformer volt ampere characteristic tester

Fully automatic and functional transformer volt ampere characteristic testersummarize

Design purpose

Designed for automatic testing of protective and metrological CT/PT, suitable for laboratory and on-site testing.

2. Reference standards

GB 1207-2006、GB 1208-2006

Fully automatic and functional transformer volt ampere characteristic testerMain features

• Support detection of CT and PT.

High current of 1000A5V, no need for external auxiliary equipment, can complete all testing items on a single machine.

Equipped with a miniature fast printer, it can directly print test results on site.

High voltage of 3000V and high power of up to 6KVA.

CT variable ratio secondary side was tested simultaneously in 6 groups.

Automatically provide CT/PT (excitation) inflection point values according to regulations.

Automatically provide 5% and 10% error curves.

Can test transformer bushing CT and GIS internal CT.

Can save 1000 sets of test data without losing it after power failure.

Supports USB flash drive data transfer, which can be read through a standard PC and generate WORD reports.

Small and lightweight ≤ 35Kg, very conducive to on-site testing.

Power on self-test, multiple protections for current and voltage.

4. Main testing functions: (see table below)

5. Main technical parameters: (see table below)

5.1. Requirements for working conditions

Input voltage 220Vac ± 10%, 25A, rated frequency 50Hz;

The tester should be powered by a power socket with protective grounding. If there is a problem with the connection of the protective ground or if the power supply is not isolated from the ground, the tester can still be used, but we do not guarantee safety;

The environmental temperature corresponding to the parameters is 23 ℃± 5 ℃;

The guaranteed value is valid for one year after factory calibration.

6. Product hardware structure

1. Panel structure: (Figure 1)

Figure 1

2. Panel annotation:

1- Equipment grounding terminal

2- USB flash drive transfer interface

3- Printer

4- LCD display

5- Controller

6- Power switch

During the current method CT ratio/polarity test, the high current output port is used

During the current method CT ratio/polarity test, there are a total of 6 sets of secondary side access ports

9- CT ratio voltage method test input port, connect CT once.

10- Voltage output port during CT/PT volt ampere characteristic test; CT/PT load test port; When PT ratio/polarity is changed, the primary side access port; CT ratio voltage method test output port, connected to CT secondary.

11- When PT ratio/polarity is changed, the secondary side is connected to the port

12- Expansion terminal (optional)

13- Host switch

14- Host power socket

7 Introduction to operation mode and main interface

7.1 Controller usage method

The controller has three operating states: "left turn", "right turn", and "press". These three operations using the controller can be conveniently used to move the cursor, input data, and select items.

7.2. Main menu (see Figure 2)

After booting up, the CT test is entered by default. The CT test main menu has 8 options, including "excitation", "load", "direct resistance", "variable ratio polarity", "AC withstand voltage", "primary current", "data query", and "PT", which can be selected and set using the rotary controller. As shown in Figure 2, when "type" is followed by a CT with a gray background, it indicates that it is currently a CT test. Rotate the cursor to "PT" and press to enter the PT testing interface, as shown in Figure 3.

The main menu of PT testing has 7 options, including "excitation", "load", "direct resistance", "variable ratio polarity", "AC withstand voltage", "data query", and "CT", which can be selected and set using the rotary controller. As shown in Figure 3, when "type" is followed by a PT with a gray background, it indicates that the current PT test is conducted. Rotate the cursor to "CT" and press to enter the CT testing interface, as shown in Figure 2.

8 CT testing

When conducting current transformer testing, please move the cursor to CT and select the corresponding testing option.

CT excitation (volt ampere) characteristic test

After selecting the "Excitation" option on the CT main interface, you will enter the testing interface as shown in Figure 4.

(1) Parameter settings:

Excitation current: The setting range (0-20A) is the highest set current output by the instrument. If the current reaches the set value during the experiment, the current will automatically stop rising to avoid damaging the equipment. Usually, if the current setting value is greater than or equal to 1A, the inflection point value can be tested.

Excitation voltage: The setting range (0-3000V) is the highest set voltage output by the instrument. Usually, the voltage setting value is slightly higher than the inflection point voltage, which can make the proportion displayed on the curve more coordinated. If the voltage is set too high, the curve will be close to the Y-axis, and if the voltage is set too low, the curve will be close to the X-axis. If the voltage reaches the set value during the experiment, the boosting will automatically stop to avoid damaging the equipment.

(2) Experiment:

The wiring diagram is shown in Figure 5. K1 and K2 of the tester are voltage output terminals. During the test, connect K1 and K2 to S1 and S2 of the transformer respectively (all terminals of the transformer should be disconnected). After checking the wiring is correct, turn on the power switch and select the "Start" option to start the test.

During the experiment, the cursor is on the "stop" option and keeps flashing. The tester starts to automatically increase the voltage and current. After the tester completes the detection, the experiment ends and the volt ampere characteristic curve is drawn (as shown in Figure 6).

Attention: The "calibration" function in Figure 4 is mainly used to view the output voltage and current values of the equipment, and is not used for transformer function testing. Please refer to Appendix 1 for details.

2) Operating instructions for volt ampere characteristic (excitation) test results

After the experiment, the screen displays the volt ampere characteristic test curve (see Figure 6). The various operation functions on this interface are as follows:

Printing: After selecting "Print" on the controller, the volt ampere characteristic (excitation) curve and data will be printed successively, making it convenient for users to make reports. Simultaneously reducing the frequency of replacing printing paper, saving time, and improving efficiency.

Excitation data: Move the cursor to select the "Excitation Data" option, and a list of test data for volt ampere characteristic tests will be displayed on the screen (see Figure 7). Press the 'Exit' button to return to the volt ampere characteristic test curve interface, and the controller can flip up and down the data. When the page cannot be flipped, it has reached the next page.

Save: Move the controller to the "Save" option and press to save the current measured data. After successful saving, the screen will display "Save Complete". After successful saving, if the user presses the "Save" button again, the program will automatically distinguish and not save the same test records. And it can be viewed in the data query menu.

Error Curve: In the interface of Figure 6, move the cursor to select "Error Curve", and the setting of the error curve for the volt ampere characteristic test will be displayed on the screen (see Figure 8). The error curve calculated after selection is shown in Figure 9.

Print settings: Move the cursor to this option and press to enter the print settings interface (Figure 10). You can choose "default" according to your requirements (the program prints a large number of voltage and current values in a certain step), or select "self setting" (the program will print according to the 10 current values in the table).

The following four items are the settings for calculating the error curve:

Load: CT secondary side rated load.

Secondary: Rated current on the secondary side of CT

ALF: Accurate limit factor, for example, if the nameplate of the tested CT is "5P10", "10" is the limit factor.

5%: Automatically calculate the 5% error curve data and display the error curve.

10%: Automatically calculate the 10% error curve data and display the error curve.

There are three options in the error curve interface:

Printing: can print error curve graphs and data;

Data: It can display error curve related data, viewed in the same way as volt ampere characteristic data.

Exit: can return to the previous menu.

3. CT ratio polarity test

(For bushing CT installed inside transformers or switchgear, it is recommended to use voltage method)

In the CT main interface, after selecting "Variable Ratio Polarity", the "Current" and "Voltage" options appear (Figure 12). Select "Current" to test using the current method, and select "Voltage" to test using the voltage method.

3.1. Polarity test of current method transformation ratio

1) Parameter settings:

In the CT "Variable Ratio Polarity" interface, select "Current" or "Voltage" and enter the testing interface as shown in Figure 13. Set the primary current to 0-1000A and the maximum current output from terminals P1 and P2 of the tester;

Secondary side rated current: 1A or 5A.

2) Experiment:

The wiring diagram is shown in Figure 14. The CT primary side is connected to P1 and P2, and the CT secondary side is connected to the corresponding 1S1, 1S2-6S1, and 6S2. The undetected secondary winding should be short circuited. After setting the rated current and number of the secondary side, close the power switch, select the "Start" option, press the controller, and the test will begin.

During the experiment, the cursor keeps flashing on the "Start" option until the experiment is completed and the automatic testing interface is exited, or the controller is pressed to manually terminate the experiment. After the device completes the test, it will automatically stop the experiment. After the experiment is completed, the results of the variable ratio polarity test will be displayed. You can choose the "Save", "Print", and "Exit" options to proceed to the next step.

The same color terminal of the instrument itself is the same phase terminal, that is, when P1 is connected to P1 of CT and S1 is connected to S1 of CT, the polarity test result is negative polarity.

3.2 Voltage method polarity test

1) Parameter settings:

In the CT "Variable Ratio Polarity" interface, select "Voltage" and enter the interface. Simply set the secondary current to 1A or 5A (refer to Figure 13).

2) Testing:

Refer to Figure 15 for wiring. Connect the small terminals L1 and L2 of the tester to the primary side of the tested CT, and connect K1 and K2 to the secondary side of the CT. After setting the rated current and number of the secondary side, turn on the power switch, select the "Start" option, press the controller, and the test will begin.

During the testing process, the cursor keeps flashing on the "Start" option until the test is completed and the automatic testing interface is exited, or the controller is pressed to manually abort the test. After the device completes the test, it will automatically stop the test. After the test is completed, the results of the variable ratio polarity test will be displayed. You can choose the "Save", "Print", and "Return" options to proceed to the next step.

The same color terminal of the instrument itself is the same phase terminal, that is, when L1 is connected to P1 of CT and S1 is connected to K1 of CT, the polarity test result is negative polarity.

5. CT primary flow test

1) Parameter settings:

In the CT main interface, select "primary current" and enter the testing interface (Figure 18). Set the current value to 0-600A.

2) Experiment:

The wiring diagram is shown in Figure 19. The CT primary side is connected to P1 and P2, and the CT secondary side is connected to the secondary load. After setting the current flow, close the power switch, rotate the controller to move the cursor to the "Start" option, press the controller, and the experiment will start. The current holding time is displayed on the progress bar (0-200A: hold for 10 minutes; Greater than 200A~300A: hold for 2 minutes; Greater than 300A: hold for 3 seconds).

6. CT AC voltage withstand test

1) Parameter settings:

In the CT main interface, select "AC withstand voltage" and enter the testing interface (Figure 20),

Set the voltage value to 0-3000V.

2) Experiment:

The wiring diagram is shown in Figure 21. The tested CT secondary side is short circuited and connected to the voltage output port K2 of the tester, and the other end K1 of the voltage output port is connected to the transformer housing. After checking the wiring, close the power switch, select the "Start" option, press it to start boosting, and the voltage holding time is set to 1 minute by default. During the testing process, the instrument detects the leakage current between the secondary winding of the transformer and the shell in real time. If the current increases rapidly, it will automatically return to zero and the page will display "Unqualified".

7. CT load test

Parameter settings:

In the CT test main interface, select to enter the "load" test interface (as shown in Figure 22), and set the rated current of the secondary side to 1A or 5A.

Resistance: Only used when testing the load box (set according to the load box nameplate)

Experiment: The K1 and K2 terminals of the tester are voltage output terminals. Refer to Figure 23 for wiring. Connect the tested load (load) to the K1 and K2 terminals of the tester. After checking the wiring is correct, select "Start" to start the experiment. After the experiment is completed, the load test results will be displayed. You can choose the "Save", "Print", and "Exit" options to proceed to the next step.

8. Direct resistance test:

1) School Zero:

In the CT testing main interface, select to enter the "Direct Resistance" test interface (as shown in Figure 24). Before the test, the test wire should be zeroed first. On the CT main interface display menu, select the direct resistance test item through the controller, enter the direct resistance testing interface and select "Zeroing". Before zeroing, connect the wire clamp of the test wire (short-circuit the test wire) (Figure 25), and then perform zeroing. After zeroing is completed, the interface prompts "Zeroing completed".

2) Experiment:

After the zero calibration is completed, refer to Figure 26 to connect the test line. Connect D1 and D2 of the tester to the tested winding. Select the "Start" button to start the test. After the test is completed, the direct resistance test results will be displayed. You can choose the "Save", "Print", and "Exit" options to proceed to the next step.

9. PT testing

When conducting a voltage transformer function test, please move the cursor to PT and select the corresponding test option.

1. PT excitation characteristic test

1) Parameter settings

In the PT test main interface, select to enter the "excitation" test interface (as shown in Figure 27),

Excitation current (0-20A): The output current is the highest set current output by the instrument. If the current reaches the set value during the test, the current will automatically stop rising. Usually, 1A can test the inflection point value.

Excitation voltage: 100V, 100/√ 3, 100/3, 150V, 220V, 350V.

2) Experiment:

Referring to Figure 28 for wiring, the voltage output terminal of the tester is connected. During the test, K1 and K2 are respectively connected to the a and x terminals of the transformer, and the zero terminal of the primary winding of the voltage transformer is grounded. After checking the wiring is correct, turn on the power switch and select the "Start" option to start the test.

During the experiment, the cursor is on the "Start" option and keeps flashing. The tester starts to automatically increase the voltage and current. After the tester completes the detection, the experiment ends and the volt ampere characteristic curve is drawn.

3) Operating instructions for PT (excitation) test results

Please refer to the CT test result description on page 8

3. PT ratio polarity test

1) Parameter settings: The testing interface is shown in Figure 30.

Once: 0-3000V.

Secondary: 100V, 100/√ 3, 100/3, 150V, 220V.

2) Start the experiment:

Refer to Figure 31 for wiring, connect PT primary side to A and X, and PT secondary side to a and x. After setting the rated voltage and number of the secondary side, close the power switch, select the "Start" option, press the controller, and the test will begin.

During the experiment, the cursor keeps flashing on the "Start" option until the experiment is completed and the test interface is exited, or the controller is pressed to manually terminate the experiment. After the experiment is completed, the results of the variable ratio polarity test are displayed. You can choose the "Save", "Print", and "Exit" options to proceed to the next step.

The same color terminal of the instrument itself is the same phase terminal, that is, when A is connected to PT A and X is connected to PT X, the polarity test result is negative polarity.

5. PT AC withstand voltage test

1) Parameter settings:

In the PT test main interface, select to enter the "AC withstand voltage" test interface (as shown in Figure 34), and set the set voltage value to 0-3000V.

2) Experiment:

Refer to Figure 35 for wiring. Short circuit the secondary side of the tested PT to the voltage output port K2 of the tester, and connect the other end K1 of the voltage output port to the transformer housing. After checking the wiring, close the power switch, select the "Start" option, press it to start boosting, and the voltage holding time is set to 1 minute by default. During the testing process, the instrument detects the leakage current between the secondary winding of the transformer and the shell in real time. If the current increases rapidly, it will automatically return to zero and the page will display that the test is not qualified.

6. PT load test

1) Parameter settings:

In the PT test main interface, select to enter the "load" test interface (as shown in Figure 36), and set the secondary voltage values: 100V, 100/√ 3, 100/3, 150V, 220V.

2) Experiment:

The K1 and K2 terminals of the tester are voltage output terminals. Refer to Figure 37 for wiring. Connect the tested load (load) to the K1 and K2 terminals of the tester. After checking the wiring is correct, close the power switch and select "Start" to start the test. After the test is completed, the load test results will be displayed. You can choose "Save", "Print", and "Exit" options to proceed to the next step.

7. Direct resistance test:

Please refer to page 14 for CT impedance testing.

Ten data query

In the main interface of CT/PT testing, select the "Data Query" test interface (as shown in Figure 38), and choose testing options such as "Excitation", "Load", "Direct Resistance", "Variable Ratio Polarity", "Angle Difference Ratio Difference", "Exit" as needed. After selecting the test item, enter the interface in Figure 39, which displays the new test results saved under that item in the instrument. You can choose the "Previous", "Next", "Transfer", "Exit", "Clean" options to perform corresponding operations.

When transferring data, insert a USB flash drive into the communication port of the tester "USB". In Figure 39, click "Transfer" to transfer the test records displayed on the current page to the USB flash drive. Each record takes about 2 seconds, and after the transfer is completed, the interface prompts "Transfer completed".

Eleven Instructions for using PC operating software

Extract the 'software' to the root directory of the C drive.

Firstly, install the "wic_x86uchs. exe" file. Secondly, install the "dotNetFx40_Full_x86ux64. exe" software to the default installation address.

After installation, open the "Voltage Ampere Characteristics" folder and select "VATeXing. exe" to open the operating software, as shown in Figure 40, which is the upper computer operating software.

11.4 In the "VATeXing. exe" operating software, select the type of transformer "CT" or "PT" below, and use the language "Chinese" or "English".

11.5 If a report format file needs to be generated, the test result data must be loaded. The specific operation method is as follows:

a）、 Connect the USB flash drive storing experimental data to the computer.

b）、 Select "Select File" in Figure 40, and the operation window in Figure 41 will appear. In Figure 41, you can load the required files as needed.

c）、 Experimental result data explanation: Data starting with "A" is the excitation characteristic result data, data starting with "B" is the variable ratio polarity result data, data starting with "C" is the load result data, and data starting with "D" is the direct resistance result data. The data starting with "E" is the angular difference ratio result data, and the data starting with "T" is the transient result data.

After loading the data in 11.6, select "OK" to display the interface shown in Figure 42. Set the corresponding parameters in the upper right corner of this interface and select "Generate Error Curve" to complete the loading of all test results.

After loading everything, you can choose "Save" or print the result data as needed.

11.8 Select the "Save" option to display the results in WORD format as shown in Figure 43.

11.9 If you need to continue loading test result data, please clean up the last loaded data first.

Appendix

Appendix 1: "Calibration" Test Method (Taking CT as an Example)

1) Parameter settings:

After entering the CT "excitation" test interface, select to enter the "calibration" test interface (as shown in Figure 44), and set the excitation current value: 0.1A-5A; Excitation voltage value: 1V to 3000V.

2) Start:

Connect the voltage calibration test according to Figure 45; After setting the measured voltage, turn on the power switch, select the "Start" option, press the controller, and the test will start. When the test reaches the set value, the output voltage/current value will be maintained for detection. After the detection is complete, press the controller, and the test will return to the interface shown in Figure 44.

The current calibration test is wired according to Figure 46. The voltage setting value is slightly higher than the current setting value (A) * load (Ω). After setting the measured current/voltage value, turn on the power switch, select the "Start" option, press the controller, and the test will start. When the test reaches the set value, the output current/voltage value will be maintained for detection. After the detection is completed, press the controller, and the test will return to the interface in Figure 44.

Appendix 2: After sales Service Commitment: This product comes with a one-year warranty and lifetime maintenance.

Appendix 3: Error Curve Explanation

The data of the 5% and 10% error curves between the current multiple (M) calculated based on the excitation current and voltage on the secondary side of the transformer and the allowable secondary load (ZII) can also be used to determine whether the transformer protection winding is qualified:

1) The actual load measured near the theoretical current multiple is greater than the theoretical load value on the transformer nameplate, indicating that the transformer is qualified as shown in Figure 45;

2) The actual current multiple measured near the theoretical load is greater than the theoretical current multiple on the transformer nameplate, which also indicates that the transformer is qualified, as shown in Figure 45;

The secondary load of the protective current transformer should meet the requirement of a 5% error curve. As long as the actual secondary load of the current transformer is less than the load allowed by the 5% error curve, the measurement error of a qualified current transformer is within 5% at the rated current multiple. The larger the secondary load, the easier it is for the iron core of the current transformer to saturate, and the smaller the allowed current multiple. Therefore, the 5% error curve, also known as the n/ZL curve, is shown in Figure 9. As shown in Figure 45 (the measured CT for protection is 5P10 20VA), where 5 is the accuracy level (error limit of 5%), P is in the form of a transformer (protection level), 10 is the accuracy limit coefficient (10 times the rated current), and 20VA represents the secondary load (capacity). When the current multiple is 10.27 times (close to 10 times), the allowable secondary load is 27.19 Ω, which is greater than the rated load of the CT by 20VA (20VA/1=20 Ω). This data can be used to determine that the transformer is qualified. In addition, when the secondary load is 19.58 Ω (close to 20 Ω), the allowable secondary load is 27.19 Ω, which is greater than the rated load of the CT by 20VA (20VA/1=20 Ω). This data can be used to determine that the transformer is qualified. In addition, when the secondary load is 19.58 Ω (close to 20 Ω), the allowed current multiple is 12.85 times, which is greater than the rated current multiple of the CT (10 times). This data can also be used to determine that the transformer is qualified. In fact, as long as either of these two key points is identified, it is possible to determine whether the measured transformer is qualified.

If the 10% error does not meet the requirements, the general approach is:

Increase the interface area of the secondary cable (reduce the secondary impedance)

Series connection of current transformers of the same type and ratio (reducing the excitation current of the transformer)

Switch to windings with higher volt ampere characteristics (increased excitation impedance)

Increase the current transformer ratio (increase excitation impedance)

Error curve calculation formula:

M =（I*P）/N ZII =（U-（I*Z2））/(K*I)

I current U voltage

N=1 (1A rated current) I current

N=5 (5A rated current) Z2 CT secondary impedance

P=20 (5% error curve) K=19 (5% error curve. 1A 5A rated current)

P=10 (10% error curve) K=9 (10% error curve. 1A 5A rated current)

Appendix 4: Time Setting Instructions

Before starting up, press the rotary controller first and do not release it. Turn on the power and wait for 3 seconds after the progress bar is completed. Release the rotary controller and you will see the interface shown in Figure 48. Rotate the "controller" to set the first two 99s to 01 and press the "controller". Move the cursor to the last two digits of 99, rotate the "controller" again, set the last two digits to 01, and press the "controller". At this point, you can enter interface 49, where you can set the time. The setting method is to first press the controller, then rotate the setting number. After setting, press the controller again to confirm, and the cursor will enter the next option.

Appendix 5: Intelligent Prompt Explanation

When conducting various tests, new users may not be proficient in wiring and operation, resulting in incorrect experimental data. In this situation, it will leave you at a loss. Based on this, we have added some simple intelligent prompts to make it easier for new users to get started and reduce errors for old users.

As shown in Figures 50 to 53, examples are provided to illustrate some common issues that may arise during the testing of volt ampere characteristics and variable ratio polarity.

Reminder for forgetting to turn on the power switch during the volt ampere characteristic test.

Prompt for wiring errors during volt ampere characteristic testing. The secondary winding of CT should be connected to K1/K2, sometimes users may mistakenly connect it to S1/S2.

During the polarity test of the variable ratio, the circuit breaker was forgotten to open or the primary current line was not connected.

The CT secondary wiring was not connected correctly during the polarity test of the variable ratio