First, high pressure tests are affected by humidity and temperature. Humidity: When the high-voltage test section is carried out, it must be carried out under shielding conditions, and the test process will be affected by the air humidity, which will affect the accuracy of the experimental data.
For the measured data, it is impossible to obtain accurate data through one test, but a large number of tests are needed to ensure the accuracy of the data, and the corresponding results can be obtained by comparing historical data with standard data. During the test, the greater the index of air humidity, the lower the accuracy of the measured results. Therefore, during the high pressure test, the influence of humidity in the air is one of the main reasons.
Affected by temperature: During the high pressure test of the hipot tester, the influence of temperature is mainly manifested in the sensitivity of the test material to temperature. The material used in the transformer is insulating. When the temperature is high, the insulation of the material will deteriorate, and the resistance value of the insulation will decrease. The main reasons are as follows:
Irregular motion of ions and molecules. The irregular motion of the molecules of the hipot tester is seriously affected by the temperature. When the temperature becomes higher, the motion of the molecules becomes violent. Similarly, ions in the insulation resistance, when the temperature increases, the movement will gradually increase. The polarity of the resistor increases, which reduces the resistance value and dissolves the water. Moisture appears in the insulation resistance. When the temperature rises, the water will dissolve into the resistance and make the resistance value smaller.
Under normal circumstances, the resistance of the resistor is inversely proportional to the temperature, so the hipot tester needs to be tested under the condition of shielding during the test. At the same time, it is necessary to ensure that the surface of the insulation resistance is clean during the experiment, which will also cause measurement errors. In addition, it should be noted that for dry transformers, the resistance of the insulation resistance of the hipot tester is proportional to the temperature before the temperature is 40 degrees.
Secondly, the relationship between leakage current and voltage polarity. Since the polarity of the transformer winding is different, the moisture contained in the resistor is also different. When the polarity of the resistance is positive, the positively charged water molecules of the hipot tester will be repelled, so that the water molecules will be reduced, and the internal current will be less, so the more current will be lost at this time; on the contrary, if it is the negative electrode, then the water molecules will increase, and the internal current will be greater.
The source of the above phenomenon is that the transformer is damp. When the voltage transformer is damp, the measured current data is inaccurate. Therefore, a new transformer should be selected to improve the accuracy of the test data measurement when carrying out the power high-voltage test.