Insulation rubber sheet withstand voltage performance test method: Each insulation rubber sheet is required to withstand voltage performance test. The inspection method is to place the insulating rubber sheet on a frame covered with a metal plate (usually available aluminum plate), and place a metal plate with each side smaller than the insulating plate 10 cm on the insulating rubber plate, and then place an electrode connected to the transformer on the metal plate. The other electrode is connected to the other side of the insulating rubber sheet, and then raised to the specified voltage at a speed of about 1000 V/s for 1 min and the reading indicated on the mA meter is recorded. Non-piercing is a good product. Insulating rubber sheets that are broken down by high voltage during inspection are allowed to be repaired at the penetration holes, but must be re-tested for withstand voltage after repair, and can only be used by qualified persons, and can only be used as secondary products.