How to test the dielectric strength of power silicone?

How to test the dielectric strength of power silicone?
Testing the dielectric strength of power silicone usually requires following certain standards and steps. The following is a general method for testing in accordance with relevant standards (such as IEC 60243, etc.):
Prepare samples:
Make flat, smooth, and uniformly thick samples from the power silicone material to be tested. The sample thickness is generally required to be 1.0mm±0.1mm. For thicker materials, appropriate processing can be performed to achieve the specified thickness.
The size of the sample is usually a circle with a diameter of not less than 50mm or a square with a side length of not less than 50mm, and the surface should be free of obvious defects, bubbles, impurities, etc.
Choose test equipment:
High-voltage test transformer: It can provide the required test voltage, its output voltage should meet the test requirements, and have sufficient capacity.
Voltage regulator: It is used to adjust the input voltage of the high-voltage test transformer, so as to smoothly increase or decrease the test voltage.
Electrode: Commonly used electrode forms include flat electrodes. Electrode materials are generally metal materials such as brass or stainless steel. The size and shape of the electrode should meet the standard requirements. Usually the diameter of the electrode is 25mm, and the edge should be smooth and free of burrs.
Voltage measuring device: Accurately measure the voltage applied to the sample, such as an electrostatic voltmeter.
Protective resistor: Connected in series in the high-voltage circuit to limit short-circuit current and protect the safety of test equipment and personnel.
Install samples and electrodes:
Place the prepared sample between two parallel flat electrodes to ensure that the sample is in close contact with the electrodes and that the sample completely covers the effective area of ​​the electrodes.
The distance between the electrodes should be equal to the thickness of the sample, and the parallelism of the electrodes must be ensured.
Set test conditions:
Select a suitable boost speed. The boost speed specified in the general standard is 2kV/s or 5kV/s (determined according to the test standards and requirements).
According to the expected dielectric strength of the sample, set the upper limit of the test voltage to prevent excessive voltage from damaging the equipment and samples.
Conduct the test:
Turn on the power supply, slowly increase the voltage through the voltage regulator, and increase the voltage evenly according to the set voltage increase speed. At the same time, closely observe the state of the sample and the changes in parameters such as voltage and current.
When the sample breaks down, that is, the current suddenly increases sharply and the voltage drops rapidly, then record the voltage value at the time of breakdown.
Repeat the test and calculate:
Test the same sample multiple times (generally not less than 5 times), and place the sample under the specified environmental conditions for a period of time (such as 10-15 minutes) between each test to eliminate the residual charge and thermal effects inside the sample.
Calculate the dielectric strength of the sample based on the breakdown voltage value obtained from the test. The calculation formula for dielectric strength is: dielectric strength = breakdown voltage / sample thickness, in kV/mm.
Result analysis and report:
Analyze the test results to evaluate whether the dielectric properties of the power silicone meet the relevant standards and requirements.
Write a test report to record the detailed information of the test sample, test equipment and conditions, test results, and analysis conclusions.