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 the stable operation of the power grid is the transformer for power 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 introduction to high-voltage testing and power transformers, the importance of power high-voltage transformer testing is proposed, and analysis is conducted from multiple factors such as voltage polarity, temperature, humidity, and boosting speed, to analyze the impact on the power high voltage test transformer.

    The power high voltage test transformer has many characteristics, such as light weight, small size, strong universality, 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 under DC high voltage or power frequency for electrical components, high-voltage equipment, and insulating materials. 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 conducting high-voltage tests on transformers, it is necessary to conduct them under shielded conditions because factors such as humidity and temperature in the air can affect the test, affecting the accuracy of the test results. Conducting high-voltage tests under shielded conditions will make the test results more accurate.

    2 Factors Affecting Test Transformer Testing

    For the safety of the test transformer, it is seriously affected by the accuracy of test data and the feasibility of the test. During high-voltage testing, there are many factors affecting 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 carried out under shielded conditions, and the test process is affected by air humidity, which affects 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 corresponding 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, during high-voltage testing, the influence of air humidity is one of the main reasons.

    Influence of temperature: During high-voltage testing, the influence of temperature is mainly manifested in the sensitivity of test materials to temperature. The material used in transformers is insulating. When the temperature is very high, the insulation performance of the material will deteriorate, 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 seriously affected by temperature. When the temperature rises, the movement of molecules will become intense. Similarly, when the temperature rises, the movement of ions in the insulation resistance will also gradually accelerate. The polarity of the resistance increases, thereby reducing the resistance value.

    Moisture dissolution. When moisture appears in the insulation resistance, as the temperature rises, the moisture will dissolve into the interior of the resistance, causing the resistance value to decrease.

    Generally, the resistance value is inversely proportional to temperature, so during the test, it is necessary to conduct it under shielded conditions. At the same time, during the experiment, it is also necessary to ensure that the surface of the insulation resistance is clean, as this can also cause measurement errors. In addition, it should be noted that for dry transformers, before the temperature reaches 40 degrees, the insulation resistance value is proportional to temperature.

    Secondly, the relationship between leakage current and voltage polarity. Due to the different polarity of transformer windings, the moisture content inside the resistance is also different. When the polarity of the resistance is positive, the positively charged water molecules will be repelled, thereby reducing the number of water molecules, and the internal current will be less, so the current lost at this time will be more; conversely, if it is negative, the water molecules will increase, and the internal current will be larger. 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 tests, 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 experiments, it is shown that the actual measured value of leakage current is affected by the boosting speed. Under the influence of the boosting speed, the actual measured value will have a certain deviation from the theoretical value. This difference is more obvious in large-capacity transformers.

    3 Preset Test Procedures

    3.1 Preparation period for the test

    Set up safety protection nets around the experiment, and post warning signs on the safety nets. Conduct the test strictly in accordance with relevant regulations and requirements. There should be dedicated personnel to guard around the safety net to strictly prevent unnecessary consequences caused by unrelated personnel approaching. The person in charge should be a professional. When conducting high-voltage tests on transformers, safety is the primary consideration and must not be ignored, otherwise unnecessary casualties will be caused. During the pressure test, professional personnel should connect the voltage and circuits, work conscientiously and responsibly, and be comprehensive.

    3.2 Key points of the test

    During the test, at least two people must cooperate, designate one person in charge, and the rest cooperate in the test. The division of labor for each link should be clear, and everyone should do their duty. Test personnel should have a certain sense of safety. Personnel unfamiliar with the test process cannot undertake this work to avoid safety accidents. The person in charge should conduct detailed and thorough inspections of each link of the test. Only after ensuring that all work is correct can they withdraw outside the safety net. After ensuring that everyone has withdrawn, the inspection can be stopped.

    Check the equipment used in the test, such as instruments and capacity checks; the wiring of the equipment should be marked to avoid wiring errors. When all preparations are ready, the chief person in charge should issue the closing instruction, and then the dedicated personnel will close the switch. During the test, all participants must be fully committed, conscientious, and responsible, and must not be careless or indifferent. The person in charge should give unified command during the test, and handle emergencies calmly.

    3.3 Inspection in the subsequent period

    After the test, carefully remove the equipment wiring and safety net, and conduct a careful survey to eliminate various hidden dangers. In fact, the inspection in the subsequent period is easily overlooked. It is necessary to focus on checking the connection status of instruments and whether various types of gates have been disconnected.

    4 Precautions during the use of high-voltage transformers

    First, connect the lines properly. In addition to connecting all lines during the test, the transformer should also be grounded with the outer shell of the operating system. At the same time, the tail ends of the high-voltage winding and the measurement winding should be safely grounded.

    Secondly, precautions during the boosting process. When the voltage regulator is at zero, close the switch, then boost at a uniform speed to the rated voltage position. At this time, observe the pointer of the instrument. If any abnormal phenomenon occurs, immediately disconnect the power, check, and then continue the test. During the experiment, the iron core of the transformer must be grounded because, according to its working principle, if it is not grounded, electric shock accidents will occur.

    5 Conclusion

    High voltage test transformer In summary, for power testing, safety is the most important issue. When conducting power high-voltage tests, most test links require staff to complete personally, which places higher requirements on safety and involves many safety factors. To improve the safety factor during the test, each test personnel must clarify their respective responsibilities, clarify the purpose and method of the test, do their duty, and improve measurement accuracy. The chief person in charge of the test should lead by example, give full play to their role, do a good job of inspection and preparation before the test, control the key links during the test, and achieve the goal of improving the reliability of electrical equipment while improving the accuracy of test data.