1. Firstly, we need to select testing equipment with appropriate capacity. If the capacity of the testing equipment is insufficient or too large, it will affect on-site testing.
2. The impact of altitude on testing requirements:
As the altitude increases, the spatial density decreases, the average free travel of electrons in the electric field increases, and electrons can collect more kinetic energy between collisions (compared to normal density), which is more likely to cause ionization, resulting in a decrease in the discharge voltage of the air medium.
3. To prevent overvoltage during testing:
If the voltage does not gradually increase from zero during the power frequency withstand voltage test, but rather the earth frame voltage on the primary winding of the test transformer appears on the test product, it is due to excitation surge overvoltage. If the power supply is suddenly cut off during testing, overvoltage may occur due to self induced potential for small capacity test samples. Both of the above situations may lead to incorrect puncture of the test item. Therefore, when conducting power frequency withstand voltage tests, the testing operation rules should be strictly followed.
4. Impact of increased capacity on test values:
In AC power frequency withstand voltage testing, the tested product is usually a capacitive load, and the high-voltage winding of the tested transformer is connected to the tested capacitor. In this way, the capacitive current flowing through the capacitive load will cause a voltage drop in the winding impedance of the test transformer, and the voltage on the secondary side of the test transformer will decrease, which is significantly greater than the calculated secondary side voltage. Conversion rate. This phenomenon is called the "capacity increase effect", and it can be seen that the original transformation ratio is not applicable. The process of increasing is directly proportional to the short-circuit impedance of the transformer, with a general increase range of about 4% to 30%.
5. The impact of pressure waveform distortion on test results:
Due to the presence of many nonlinear loads in the power unit, the number of harmonic circuit components increases, and the problem of voltage waveform distortion in the power grid is becoming more and more serious. In order to protect the correctness of the test results, it is necessary to measure their peak value to eliminate measurement errors caused by voltage splashing distortion.
In actual power frequency withstand voltage tests, the following points should also be noted:
1. The test transformer and control box should be reliably grounded;
During the testing process, the boosting speed should not be too fast, and sudden opening or closing of full voltage is not allowed;
3. Test items should be cleaned and dried to avoid damage and errors caused by testing;
4. During the testing process, if the test product experiences a short circuit or breakdown, the overcurrent relay in the control box will operate. At this time, before removing the test product, reset the Pressure regulator to zero and cut off the power supply.
5. When conducting high-voltage AC/DC testing, two or more personnel must participate, and the division of labor should be clearly defined and each other's methods should be clearly defined. And there are dedicated personnel to supervise on-site safety and observe the testing status of the tested products;
6. During the voltage boosting or voltage withstand test, if any of the following abnormal situations are found, the voltage should be immediately reduced and the power should be cut off to stop the test. The test should be carried out in the case of the cause.
The ZC-501A series oil immersed test transformers are particularly suitable for conducting insulation strength tests on various high-voltage electrical equipment, electrical components, and insulation materials under power frequency or DC high voltage in power systems, industrial and mining enterprises, scientific research departments, and other fields. It is an essential and important equipment in high-voltage testing.
Kvtester Electronics Technology Co.,Ltd. is a high-tech enterprise specializing in power testing, testing, research and development, production, and sales of testing equipment. It has been engaged in the electrical testing industry for many years, and its products are of high quality. We welcome customers to come and purchase.
