DC resistance testerAdopting a dual power supply structure, the YN winding of the transformer with tap connections is connected to achieve simultaneous three-phase power supply. The measurement system adopts independent three channel current sampling and independent three channel voltage sampling, while measuring and displaying the three-phase resistance value and three-phase unbalance rate. Greatly reducing working time and solving the problem of long testing time for DC resistance of various tap windings in power transformers, the required time is only one-third of traditional methods. The entire testing process is controlled by an automatic program, ensuring no misoperation. Full Chinese LCD display with high clarity and easy operation. The instrument comes with a micro printer that can automatically print test results.
1. Usage conditions:
Operating environment temperature: -10~40 ℃ Operating environment humidity: ≤ 90%
2 Technical parameters:
2.1 Power supply: AC 220V ± 10%, frequency 50 ± 1Hz;
2.2 Resistance measurement range: 0-100 Ω, resolution of 0.1 u Ω;
2.3 Accuracy of resistance measurement: 0.2% ± 1 μ Ω;
2.4 Current source output: automatic selection of current (up to 20A);
3 DC resistance testerTesting and operation methods
3.1 Wiring: Connect the tested object to the testing terminal of the machine through a cable, ensure a secure connection, and also connect the ground wire.
3.1.1 Single channel direct measurement wiring. See Figure 1.
The resistance between AO phases can be directly measured as shown in Figure 1.
3.1.2 Three channel direct measurement wiring. See Figure 2.
The resistance values of AO, BO, and CO phases can be directly measured simultaneously, as shown in Figure 2.
3.2 Power on interface: Turn on the power switch, and the screen will display the interface shown in Figure 3. After staying for about 3 seconds, it will automatically skip to enter the main interface for selecting settings, as shown in Figure 4:
3.3 Channel Selection Interface: The screen displays the interface shown in Figure 4. At this time, the corresponding "channel" function key can be used to select the channel of the tested product. Every time the key is pressed, "three" and "single" will cycle on the screen.
3.4 Test: After selecting the channel, press the test button to start the test. The display screen shows the charging current value and prompts "charging...". The system clock starts counting and displays the time from charging to testing. After one hour, it starts counting again from zero without affecting the testing process. After the current stabilizes, the display screen shows the test current being used and prompts "Testing...". Then, the single channel displays the interface shown in Figure 5, and the three channel displays the interface shown in Figure 6. Observe that the test current and resistance values are stable, and the instrument continues to test continuously.
3.4.1 "Double Side" function, after displaying as shown in Figure 5/6, pressing the "Double Side" function button can re measure but maintain the current unchanged. This function can clear old data in the internal buffer and remeasure new data to achieve rapid stabilization of available data.
3.4.2 "Conversion" function, after displaying as shown in Figure 5/6, press the "Conversion" function key to display as shown in Figure 7. Enter the current temperature of the tested product, ranging from -99.9 ℃ to 199.9 ℃. After entering, press the "Return" key to return to the testing interface. The testing interface will display the oil temperature of the tested product and the resistance value when converted to 75 ℃. The "Conversion" function key will change to "Cancel". Press the "Cancel" function key to cancel the conversion function and return to Figure 5/6. Switching between "Conversion" and "Cancel" does not affect the testing process.
3.4.3 "Print" function, after displaying as shown in Figure 5/6, press the "Print" function key to display a prompt: "Do you want to edit?" Select "No" to print the displayed data "Print completed" and return to the previous level of testing interface. Select 'Yes' to display as shown in Figure 8. Correctly input the winding, phase, and tap, then press the "Return" button. A prompt will appear: "Do you want to edit?" Select "No" to print the displayed data. "Print completed" returns to the previous testing interface. Select 'Yes' to re edit. Print the conversion result when there is oil temperature input. Note that "phase difference" cannot be entered during the three channel test.
3.4.4 "Save" function, after displaying as shown in Figure 5/6, press the "Save" function key to save the measured data and test save time. If there is oil temperature input, save the converted results. Once saved, it will display "Save Complete!" and return to the previous interface. The saved data can be viewed through the "Retrieve" function key in the main startup interface.
3.5 Time Adjustment: In the startup interface, press the "Time" function key to enter the time adjustment interface. After adjusting the completion time, press the "Return" key to return to the startup interface and complete the time modification.
3.6 Data retrieval: On the startup interface, press the "retrieval" function key to enter the view record interface, which can be viewed in a loop and can store up to 80 sets of data for viewing. Press the "return" key to return to the startup interface.
4 DC resistance testerNotes:
4.1 This instrument can be used both indoors and outdoors, but it should be avoided from places such as rainforests, corrosive gases, excessive dust, high temperature and pressure, direct sunlight, and severe vibrations.
4.2 The use, maintenance, care, and adjustment of instruments should be carried out by professionals.
Before using the instrument for testing, confirm the wiring and ensure that the joints are not loose. Only after confirming that there are no errors can the test be carried out.
During the testing process, it is prohibited to move the test clamp and power supply line.
Before testing the no-load tap changer of the transformer, it must be reset. After the discharge is completed, the alarm sound should stop before switching the tap changer.
Before disconnecting, be sure to wait until the discharge is complete and the alarm stops before proceeding with the disconnection.
4.8 When using three channels, be aware that the initial establishment time of the magnetic circuit may be longer during data testing, and the stabilization time may be shortened during switching and tapping.
4.9 After the measurement is completed and the discharge is finished, there may be residual current in the wire, which may cause ignition and discharge during the dismantling process. This is a normal phenomenon, but attention should be paid to wearing personal protective equipment during operation.