Safety Capacitance Knowledge Essentials (2)

3. Safety certification

1). As a Y capacitor in the safety capacitor series, it is required to obtain certification from a safety inspection agency. The appearance of Y capacitors is mostly blue and round, and they are marked with safety certification marks (such as UL, VDE, ENEC, CQC, KC, etc.) and withstand voltages AC300V and AC400V. The highest test withstand voltage is up to 2600V and 4000V. It should be noted that the safety Y capacitor should not be used as a substitute for ordinary ceramic capacitors.

2). As one of the safety capacitors, the X capacitor is also required to obtain the certification of the safety inspection mechanism. X capacitors are generally marked with safety certification mark and withstand voltage AC300V or AC275V, but their true DC withstand voltage is as high as 2000V or more. Do not use the ordinary capacitors such as AC250V or DC400V at random. .

4. Safety capacitor breakdown problem

If the Cx capacitor in the filter is broken down, it is equivalent to short circuit of the AC grid, at least causing the equipment to stop working; if the y capacitor is broken down, it is equivalent to adding the voltage of the AC grid to the outer casing of the equipment, which directly threatens personal safety and affects The safety of any circuit or device that is referenced to a metal enclosure often results in the burning of certain circuits or equipment.