PT tester

The PT tester measures 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.

One chapterPT testerScope of use and technical specifications

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 2PT 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",