Firstly, high-voltage testing is affected by humidity and temperature; Humidity: During the high-voltage test section, it must be conducted under shielded conditions, and the accuracy of the experimental data may be affected by the humidity of the air during the test process; For measured data, it is impossible to obtain accurate data through one experiment, and a large number of experiments are needed to ensure the accuracy of the data. Corresponding results can be obtained by comparing historical data with standard data; During the experimental process, the higher the humidity index of the air, the lower the accuracy of the measured results. Therefore, the influence of humidity in the air is one of the main reasons for high-voltage testing.Affected by temperature: During high-voltage testing, the influence of temperature is mainly manifested in the sensitivity of the test material to temperature. The material used in transformers is insulated, and when the temperature is very high, the insulation properties of the material will deteriorate, and the resistance value of the insulation will decrease. The main principle is as follows:
Irregular motion of ions and molecules. The irregular motion of molecules is severely affected by temperature. As the temperature increases, the motion of molecules will become more intense. Similarly, ions in insulation resistors will gradually accelerate their motion as the temperature rises, increasing the polarity of the resistor and reducing its resistance.
Dissolve water. Moisture appears in the insulation resistor, and when the temperature rises, the moisture will dissolve into the interior of the resistor, causing the resistance value to decrease.
Under normal circumstances, the resistance of a test transformer is inversely proportional to temperature, so it is necessary to conduct the test under shielding conditions. At the same time, it is also necessary to ensure the surface cleanliness of the insulation resistance during the experiment, which can cause measurement errors; Additionally, it should be noted that for the test transformer, the resistance of the insulation resistance is directly proportional to the temperature before reaching 40 degrees Celsius.
Secondly, the relationship between leakage current and voltage polarity. Due to the different polarities of transformer winding, the moisture content inside the resistor is also different. When the polarity of the resistor is positive, positively charged water molecules will be repelled, resulting in a decrease in water molecules and a decrease in internal current. As a result, more current will be lost at this time. Conversely, if it is negative, water molecules will increase, and the internal current will be larger. The source of the above phenomenon is transformer moisture. When the voltage transformer is damp, the measured current data is inaccurate. Therefore, when conducting high-voltage power tests, a new transformer should be selected to improve the accuracy of test data measurement.