Hipot tester, also known as electrical insulation strength tester, or dielectric strength tester, also known as dielectric breakdown device, dielectric strength tester, high voltage tester, high voltage breakdown device, hipot tester etc. A test of applying a specified AC or DC high voltage between the live part and the non-live part (usually the casing) of the electrical appliance to check the withstand voltage capability of the insulating material of the electrical appliance. In the long-term operation of the electrical appliance, not only the rated working voltage, but also the short-term overvoltage effect that is higher than the rated working voltage caused by the operation process (the overvoltage value may be several times higher than the rated working voltage value). Under the action of these voltages, the internal structure of the electrical insulating material will change.
When the overvoltage intensity reaches a certain value, the insulation of the material will break down, the electrical appliance will not operate normally, and the operator may be electrocuted, endangering personal safety.
The main test indicators of electrical safety include AC/DC withstand voltage, insulation resistance, leakage current, grounding resistance, etc. The AC/DC hipot tester is used to test the electrical safety performance of the product under the actual working state, and is one of the important indicators for testing the electrical safety performance of the equipment.
At present, the hipot tester seen on the market adopts the GB4706 (equivalent to IEC1010) standard, and most of them are single-item test indicator test instruments with a desktop structure, which cannot meet the needs of users for comprehensive testing of multiple indicators; Most of the testers use traditional test methods, the test accuracy is not high, the technology and main performance indicators used have a certain gap with the foreign advanced level, and cannot fully meet the needs of the current development of electrical safety performance testing. Therefore, it is of great significance to study the withstand voltage test system that adopts advanced technology and has better performance indicators in line with the latest international standards.
The hipot tester is mainly used for the withstand voltage test of polyethylene insulated power cables, and can also be used for the insulation withstand voltage test of large power transformers. The hipot tester uses ultra-low frequency high voltage to test the withstand voltage of power cables.
The withstand voltage test refers to the test of the withstand voltage capability of various electrical devices, insulating materials, and insulating structures. The process of applying a high voltage to an insulating material or insulating structure without destroying the properties of the insulating material is called a hipot tester. Generally speaking, the main purpose of the withstand voltage test is to check the ability of the insulation to withstand working voltage or overvoltage, and then check whether the insulation performance of the product equipment meets the safety standards.
The basic principle of the withstand voltage test: Apply a voltage higher than the normal working voltage to the insulator of the device under test and continue for a specified. If the insulation between them is good enough, the voltage applied to it will only generate a small amount of voltage. leakage current. If a device under test insulator maintains its leakage current within the specified range for a specified, it can be determined that the device under test can operate safely under normal operating conditions. When the withstand voltage test is performed, the technical specifications of the tested product are different, and the measurement standard is also different. For the general device under test, the withstand voltage test is to measure the leakage current value between the live wire and the chassis. The basic rule is: take twice the working voltage of the object under test plus 1000V as the standard voltage for the test. The test voltage of some products may be higher than this specified value.
According to the provisions of IEC61010, the test voltage must gradually rise to the required test voltage value (such as 5kV, etc.) within 5s to ensure that the test voltage value is stably applied to the insulator under test for not less than 5s. At this time, the leakage of the tested circuit by comparing the current value with the leakage current threshold specified in the standard can be judged whether the insulation performance of the tested product meets the standard. After the test, the test voltage must be gradually reduced to zero within the specified time.