High-voltage test transformer manufacturers, with the continuous development of China's economy, have increasingly higher requirements for the safety and reliability of power grid operation. One of the effective facilities to ensure stable operation of the power grid is the transformer for high-voltage testing. For the power system, the power high-voltage test transformer has extremely special significance and plays an important role. Through a brief description of high-voltage testing and power transformers, the importance of power high-voltage transformer testing is proposed, and multiple factors such as voltage polarity, temperature, humidity, and boosting speed are analyzed to identify their impact on the power high-voltage test transformer.
The power high-voltage test transformer has many characteristics, such as light weight, small size, strong versatility, complete functions, and compact structure. It is very convenient to use and is indispensable for the power system, playing an important role. The power high-voltage test transformer is suitable for industrial and mining enterprises, power systems, and scientific research departments, facilitating insulation tests of electrical components, high-voltage equipment, and insulating materials under DC high voltage or power frequency. In high-voltage testing, the power high-voltage test transformer is one of the important test equipment. This article will study and analyze the transformer for power high-voltage testing.
1. Brief Introduction to Electrical High-Voltage Testing
The main purpose of conducting electrical high-voltage testing is to check whether the insulation of electrical equipment is good and whether all functions are normal, to ensure that the electrical equipment can operate normally. When performing high-voltage testing on transformers, it should be carried out under shielded conditions because humidity and temperature in the air can affect the test, impacting the accuracy of the test results. Conducting high-voltage tests under shielded conditions will yield more accurate results.
2. Factors Affecting Test Transformer Testing
For the safety of the test transformer, the accuracy of test data and the feasibility of the test are seriously affected. During high-voltage testing, many factors affect the test. The main influencing factors are analyzed one by one below.
First, high-voltage testing is affected by humidity and temperature. Humidity: When conducting high-voltage tests, it must be done under shielded conditions, and the test process is affected by air humidity, which impacts the accuracy of experimental data. For the measured data, it is impossible to obtain data through a single test; a large number of tests are needed to ensure the reliability of the data, and results are obtained by comparing historical data with standard data. During the test, the higher the air humidity index, the lower the accuracy of the measured results. Therefore, in high-voltage testing, the influence of air humidity is one of the main reasons.
Influence of temperature: During high-voltage testing, the effect of temperature is mainly manifested in the sensitivity of test materials to temperature. The materials used in transformers are insulating. When the temperature is very high, the insulation performance of the material deteriorates, and the insulation resistance value will decrease. The main principles are as follows:
Irregular movement of ions and molecules. The irregular movement of molecules is severely affected by temperature. When the temperature rises, the movement of molecules becomes more intense. Similarly, in insulating resistance, when the temperature rises, the movement of ions also gradually accelerates. The polarity of the resistance increases, thereby reducing the resistance value.
Moisture dissolution. When moisture appears in the insulating resistance, as the temperature rises, the moisture dissolves into the interior of the resistance, causing the resistance value to decrease.
Generally, the resistance value is inversely proportional to temperature, so during testing, it is necessary to conduct the test under shielded conditions. At the same time, during the experiment, it is also necessary to ensure that the surface of the insulating resistance is clean, as this can also cause measurement errors. Additionally, it should be noted that for dry transformers, before the temperature reaches 40 degrees, the insulation resistance value is proportional to temperature.
Second, the relationship between leakage current and voltage polarity. Due to the different polarity of the transformer winding, the moisture content inside the resistance is also different. When the polarity of the resistance is positive, water molecules with positive charges will be repelled, thereby reducing the number of water molecules, and the internal current will be less, so the leakage current will be greater; conversely, if it is negative, the water molecules will increase, and the internal current will be greater. The root cause of the above phenomenon is the dampness of the transformer. When the transformer is damp, the measured current data is inaccurate. Therefore, when conducting power high-voltage testing, a new transformer should be selected to improve the accuracy of test data measurement.
Finally, the influence of boosting speed on the test. Leakage current is caused by the dampness of the transformer. The generation of this current is related to factors such as air humidity, temperature, cleanliness of the insulator surface, and voltage. Whether the leakage current is affected by the boosting speed? In fact, the leakage current is affected by the boosting speed. Through a large number of tests, it has been shown that the actual measured value of leakage current is affected by the boosting speed. Under the influence of boosting speed, the actual measured value will deviate from the theoretical value, and this difference is more obvious in large-capacity transformers.
3. Preset Test Procedure
3.1. Preparation Phase of the Test
Before conducting the high-voltage test, sufficient preparation work must be done. First, check whether the test equipment is intact, whether the wiring is correct, and whether the grounding is reliable. Second, check whether the test environment meets the requirements, such as temperature and humidity. Third, check whether the test personnel have the corresponding qualifications and are familiar with the test procedures. Only when all preparations are in place can the test be carried out.
