DC resistance tester is a professional instrument used to measure the DC resistance of electrical equipment such as transformers, motors, cables, etc. Its usage involves key steps such as wiring, testing, data processing, and safe operation. The following is a detailed usage guide:
1. Preparation before testing
① Equipment inspection:
Check if the appearance of the DC resistance tester is intact, without damage or cracks.
Confirm that the power cord, testing cable, and other accessories of the tester are complete and undamaged.
Check if the display screen, buttons, etc. of the tester are working properly.
② Preparation of tested equipment:
Ensure that the tested equipment (such as transformers, motors, etc.) is powered off and in a safe state.
For transformers, it is necessary to completely disconnect their windings from other circuits to avoid parallel branches affecting the test results.
Clean the wiring terminals of the tested equipment to ensure good contact.
③ Environmental preparation:
Choose a testing environment that is dry, ventilated, and free from strong electromagnetic interference.
Ensure that the testing site is free of flammable and explosive materials and meets safety operation requirements.
2. Wiring operation
① Select test line:
Select the appropriate test line based on the resistance range of the device being tested. Generally, test lines are divided into thick lines and thin lines. Thick lines are used to measure low resistance values, while thin lines are used to measure high resistance values.
Ensure that the length of the test line is sufficient and the connection is firm to avoid poor contact.
② Wiring method:
Four wire connection method: suitable for high-precision measurement, especially for low resistance measurement. Connect the current output terminals (I+, I -) and voltage measurement terminals (V+, V -) of the tester to the two ends of the device under test, forming independent current and voltage measurement circuits.
③ Three wire connection method: When the four wire connection method cannot be achieved, the three wire connection method can be used. Connect one test wire of the tester to both one end of the device under test and the voltage measurement terminal, and connect the other test wire to the other end of the device under test and the current output terminal. However, it should be noted that the three wire connection method may introduce certain measurement errors.
④ Two wire connection method: only suitable for high resistance measurement and situations with low accuracy requirements. Connect the two test wires of the tester to the two ends of the device under test.
Wiring example (taking transformer winding test as an example):
Connect the current output terminals (I+, I -) of the tester to the two ends of the transformer winding through thick test wires.
Connect the voltage measurement terminals (V+, V -) of the tester to both ends of the same winding through thin test wires, ensuring that the voltage measurement circuit is independent of the current circuit.
Confirm that the wiring is secure and free from looseness or short circuits.
3. Parameter settings
① Select testing mode:
According to the testing requirements, choose single-phase testing or three-phase testing mode. The three-phase testing mode can simultaneously measure the resistance values of three-phase windings, improving testing efficiency.
② Set test current:
Select the appropriate test current based on the capacity and resistance range of the device being tested. The general testing current should be greater than 2% -10% of the rated current of the tested equipment to ensure testing accuracy.
For large capacity transformers or low resistance equipment, a larger test current should be selected; For small capacity transformers or high resistance devices, a smaller test current can be selected.
③ Set testing time:
Set an appropriate testing time based on the characteristics of the device being tested. The general testing time should be long enough to ensure that the tested equipment reaches a stable state; But it should not be too long to avoid the equipment overheating affecting the test results.
④ Other parameter settings:
According to the functions of the tester, set parameters such as data storage, printing, and temperature conversion.
4. Start testing
① Start the tester:
Connect the power of the tester, press the start button or confirm button to start the test.
② Observe the testing process:
Observe the display screen of the tester to confirm whether the parameters such as test current and voltage are normal.
Pay attention to whether there are any abnormal sounds or odors during the testing process. If there are any abnormalities, stop testing immediately and investigate the cause.
③ Waiting for testing to complete:
The tester will automatically complete the testing process and display the test results. The testing time depends on the characteristics of the tested equipment and the magnitude of the testing current.
5. Data Processing and Analysis
① Read test results:
After the test is completed, read the test results from the display screen of the tester, including parameters such as resistance value, test current, and test time.
② Data recording and storage:
To record test results, the data storage function of the tester or manual recording can be used.
For important test data, it is recommended to save it to a computer or cloud storage device for subsequent analysis.
③ Data analysis and judgment:
Based on the test results, determine whether the DC resistance of the tested equipment meets the standard requirements.
For transformer windings, the resistance values of each phase winding can be compared to determine whether there are defects such as inter turn short circuits or winding deformations.
If the test results are abnormal, it is necessary to further check the wiring, insulation, and other conditions of the tested equipment and retest.
6. Operation after testing
① Disconnect the power supply of the tester:
After the test is completed, disconnect the power supply of the tester first, and then remove the test line.
② Dismantling the testing line:
Remove the test line in the order of first removing the voltage measurement terminal and then removing the current output terminal to avoid arcing or damaging the tester.
③ Organize equipment and site:
Arrange the testing equipment, testing lines, and other accessories back in place to keep the device tidy.
Clean up the testing site to ensure there are no remaining items or safety hazards.
7. Safety precautions
① Comply with safety operating procedures:
During the testing process, strictly follow the safety operating procedures and wear necessary protective equipment (such as insulated gloves, protective goggles, etc.).
② Preventing electric shock:
Ensure that both the tester and the tested equipment are powered off and reliable grounding measures are taken.
When wiring or dismantling test lines, avoid direct contact with live parts by hand.
③ Prevent equipment damage:
Choose appropriate testing current and testing time to avoid excessive testing current or long testing time that may cause the tested equipment to heat up or be damaged.
During the testing process, if abnormal heating or smoking is found in the tested equipment, the testing should be stopped immediately and the cause checked.
④ Avoid strong electromagnetic interference:
When testing in a strong electromagnetic field environment, anti-interference measures should be taken (such as using shielded wires, staying away from interference sources, etc.) to ensure the accuracy of the test data.
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Kvtester Electronics Technology Co.,Ltd. is a high-tech enterprise specializing in power testing, testing, research and development, production, and sales of testing equipment. It has been engaged in the electrical testing industry for many years, and its products are of high quality. We welcome customers to come and purchase. Service hotline: 0086-27-81778799, to learn more, visit the official website: www.kvtester.com
