Measuring the DC resistance of the windings is a very important test item in preventive tests and handover tests of electrical equipment. By measuring the DC resistance of the winding, defects such as poor contact, poor welding, and broken strands can be found in time at the wire joints, leads and tap-changers inside the winding. In order to complete this test task quickly and accurately, the DC resistance fast tester has become an indispensable test tool. This article will introduce in detail the operation method of DC resistance fast tester in AC and DC testing.
First, the basic principle of DC resistance fast tester
The DC resistance tester works based on Ohm's law and calculates the DC resistance value of the winding by applying a DC current to the winding under test and measuring the voltage drop across its ends. The tester usually has a high test speed and measurement accuracy, and can quickly complete the DC resistance measurement of the winding.
Second, the operation method of AC and DC test
PreparationFirst, make sure that the connection between the tester and the device under test is safe and reliable. Check whether the test line is intact and free of broken or exposed parts to ensure personal safety and equipment safety during the test.
Set the test parameters: According to the rated voltage and rated current of the tested winding, select the appropriate test current. In general, the higher the test current, the higher the measurement accuracy, but at the same time, the bearing capacity of the winding under test should also be considered.
Start testing: Correctly connect the test lead of the tester with the winding to be tested, start the tester, and start the measurement. During the test, attention should be paid to the display and indication of the tester to ensure that the test is carried out normally.
Read and record data: After the test is completed, read the DC resistance value displayed by the tester and record it. At the same time, attention should be paid to observe other displays and indications of the tester, such as test time, test current, etc., for subsequent analysis and processing.
End the testAfter confirming that the data is correct, turn off the tester and disconnect the test line from the winding under test.
While DC resistance fast testers are primarily used for DC testing, AC testing can also be performed in certain situations, such as when it is necessary to measure the AC impedance of windings or perform other AC characteristic tests. Here's how the AC test works:
Choose the right AC power sourceAccording to the test requirements, select the appropriate AC power source to ensure that its frequency, voltage and current meet the test requirements.
Connect the test lead: Properly connect the AC power supply, the tester and the winding under test. Pay attention to the connection method and sequence of the test leads to ensure the accuracy of the test results.
Set the test parametersAccording to the characteristics of the winding under test and the test requirements, set the appropriate test parameters, such as test frequency, test voltage, etc.
Start testing: Start the AC power supply and tester to start the AC test. During the test, you should pay attention to the display and indication of the tester to ensure that the test is carried out normally.
Read and record data: After the test is completed, read the AC impedance value or other relevant parameters displayed by the tester and record it. At the same time, attention should be paid to observing other displays and indications of the tester for subsequent analysis and processing.
End the testAfter confirming that the data is correct, turn off the AC power and tester, and disconnect the test wire from the winding under test.
3. Precautions
Safe operation: When conducting AC and DC tests, the safety operation procedures should be strictly adhered to to ensure personal safety and equipment safety. Especially when performing high-voltage tests, necessary safety measures should be taken, such as wearing insulating gloves, using insulating pads, etc.
Wiring correctlyDuring the test, it is necessary to ensure the correct connection between the test line and the winding to be tested to avoid the occurrence of wrong connection or missing connection. At the same time, attention should be paid to the good contact of the test line to avoid test errors caused by poor contact.
Test environment: During the test, it should be ensured that the test environment meets the requirements, such as temperature, humidity, etc. should be within the specified range. Avoid testing in harsh environments such as high temperatures, humidity, or strong electromagnetic fields.
Instrument calibrationIn order to ensure the accuracy of the test results, the DC resistance rapid tester should be calibrated and maintained regularly. Relevant standards and specifications should be followed during the calibration process to ensure the accuracy and reliability of the instrument.
Fourth, summary
DC resistance fast tester plays an important role in AC and DC testing, and the accuracy and reliability of the test results can be ensured through the correct operation methods and precautions. In practical application, the appropriate test method and parameters should be selected according to the characteristics of the winding to be tested and the test requirements, and attention should be paid to the safe operation and environmental protection during the test process. Through continuous technological innovation and application practice, the DC resistance rapid tester will play a greater role in the preventive test and handover test of electrical equipment.