What is the difference between the partial discharge test and the hipot test?
Both of partial discharge test and the Hipot test are important methods for inspecting the insulation of power equipment. However, there are significant differences in their detection targets, technical principles, and application scenarios. The Hipot test focuses on verifying the overall withstand capability of insulation by applying high voltage, while the PD test is used to suppress the partial discharge of the equipment during the test to detect potential insulation defects of the test object accurately.
Hipot test: This test mainly examines the overall strength of the main insulation of the equipment. By applying a test voltage higher than the rated working voltage (usually lasting for 1 to 5 minutes), it determines whether the insulation has been broken down or has severe leakage. The core objective is to verify the "resistance to damage" of the insulation. By applying high voltage through the power frequency test transformer or the series resonance test system, and using the insulation material's tolerance ability under a strong electric field to determine its qualification.
Partial discharge test: Based on the withstand voltage test, the focus is on detecting the partial discharge signals of the test object under high voltage. At the same time, it is required that the partial discharge quantity of the test device itself be extremely low (without discharge characteristics) to avoid interfering with the true partial discharge signals of the test object. The core objective is to discover "microscopic defects" inside the insulation (such as manufacturing defects, aging damage, and so on). By using special insulating materials and optimizing the electric field design, the partial discharge quantity of the testing device itself is extremely low (usually < 5 pC), ensuring the accuracy of the partial discharge signals of the test objects.