What is contact resistance?

Simply put, contact resistance refers to the obstruction encountered when current passes through two objects in contact with a surface. In power equipment, there are contact points such as circuit breakers, isolating switches, and busbar connections. If the resistance of these contact points is too high, it can cause local heating, which may lead to equipment failure and even safety accidents in the long run.

What factors can cause trouble?

Surface condition: The oxide layer, dirt, oil stains, etc. on the contact surface will significantly increase the contact resistance. Imagine if there is a layer of "dust" between two contact surfaces, how can the current flow smoothly?

Contact pressure: Adequate contact pressure is the key to ensuring low resistance. If the pressure is insufficient, the contact area will decrease and the resistance will naturally increase.

Environmental factors: Temperature, humidity, and other environmental factors may also affect the measurement results. For example, high temperature may cause material expansion and change the contact state.

Testing methods and equipment: The accuracy of the testing instrument, the connection method of the testing cable, and the magnitude of the testing current all directly affect the accuracy of the measurement results. The engineers of Wuhan UHV Power Technology Co., Ltd. have conducted in-depth research and strict control over these links in the research and production process.

Clever use of tools, precise measurement

Faced with these influencing factors, we need powerful tools and scientific methods.

Professional contact resistance tester: Choosing a high-precision and stable performance testing instrument is crucial. There are various types commonly available on the market, such as portable and high-precision digital, which can meet the needs of different scenarios. The contact resistance tester provided by Wuhan UHV Power Technology Co., Ltd. enjoys a good reputation in the industry for its excellent performance and stable performance.

Clean contact surface: Before testing, it is necessary to clean the contact surface, remove oxide layers, oil stains, etc., to ensure good conductivity.

Standardized testing process: Strictly follow the instrument manual and relevant operating procedures for testing, ensure that the testing cables are securely connected, and select the appropriate testing current.

How can we do better?

To achieve more reliable measurement results, in addition to the basic requirements mentioned above, we can also:

Take the average of multiple measurements: increase the number of measurements, eliminate accidental errors, and improve the representativeness of the results.

Compare historical data: Compare the measurement results with the historical data of the equipment to promptly identify any abnormal trends.

Analysis based on the actual situation of the equipment: Do not rely solely on test data to make judgments, but also conduct comprehensive analysis based on the appearance inspection, operating status, and other information of the equipment.

Regular calibration of instruments: Ensure the accuracy of the testing instruments themselves, and perform regular calibration and maintenance.

The measurement of contact resistance is a meticulous task that is related to the safe operation of the power system. By understanding the influencing factors, selecting appropriate tools, and adopting scientific contact resistance testing methods, we can greatly improve the accuracy and reliability of measurement data. Wuhan UHV Power Technology Co., Ltd. has always been committed to providing the most professional testing solutions for the power industry, helping users complete various testing tasks more efficiently and safely.

frequently asked questions

Q: Why do I always get unstable readings when using a contact resistance tester? A: Unstable readings may be related to factors such as unclean contact surfaces, insufficient contact pressure, poor contact of test cables, or environmental interference. Attempt to clean the contact surface, ensure pressure, and check cable connections.

Q: What are the qualification criteria for contact resistance testing? A: The qualification standards may vary depending on the type of equipment, voltage level, and specific standards. Usually, it is necessary to refer to relevant national standards or industry specifications, as well as the recommended values of equipment manufacturers.

Q: What impact does the magnitude of the test current have on the measurement of contact resistance? A: The magnitude of the test current will affect the oxide and lubricating layers on the contact surface, thereby affecting the measurement results. The appropriate test current should be selected according to the requirements of the tested equipment and instrument.

Q: Which devices require contact resistance testing? A: Any equipment involving current connection points, such as circuit breakers, isolating switches, transformers, busbar connections, etc., may require contact resistance testing.

Q: What should I do if I find that the contact resistance exceeds the standard? A: Firstly, it is necessary to confirm whether it is a measurement error. If it does exceed the standard, the contact surface should be cleaned, the contact pressure should be adjusted, damaged parts should be replaced, and re measured and confirmed according to the situation.