一、Safety capacitor

The reason why safety capacitors are called safety regulations is that they are used in such occasions: that is, after the capacitor fails, it will not cause electric shock or endanger personal safety. Safety capacitors include X capacitors and Y capacitors. The difference between ordinary capacitors is that even after the external power supply is disconnected, the internal stored charge of ordinary capacitors will remain for a long time, but safety capacitors will not appear. question. Most of the safety capacitors are blue, yellow, gray and red.

1、Safety x Capacitor

The X capacitor is connected across the two lines of the power line, that is, between "L-N". The X capacitor can suppress the differential mode interference. Usually, a metallized film capacitor is used, and the capacitance capacity is uF level. Most X capacitors are square, which is similar to the shape of a box, and are generally marked with safety certification marks, withstand voltage words (usually AC300V or AC275V), and rely on standards on their surface. Although X capacitors are a type of CBB capacitors, not every type of CBB capacitors can be used as X capacitors and must meet safety standards.

2、Safety Y capacitor

Y capacitors are usually ceramic capacitors, which generally appear in groups. Most of them have a flat circular appearance and a blue color, which can suppress common mode interference. The capacity of Y capacitors is nF level. Based on the restriction of leakage current, the Y capacitance should not be very large. Most of the Y capacitors are suitable for isolation occasions. According to the IEC standard, the minimum clearance of Y1 products is 8.0mm, and the clearance of Y2 products is not less than 6.3mm. As isolation products, the safety distance should be enough to avoid arcing when high voltage is energized.

二、Selection of safety capacitors

X-type safety capacitors are divided into three types: X1, X2, and X3 according to the withstand voltage. The allowable peak pulse voltage overvoltage level in the safety level of safety capacitors:2.5kV＜X1≤4.0kV、X2≤2.5kV、X3≤1.2kV

Y-type safety capacitor safety level:Y1≥250V，Allowable peak pulse voltage＞8KV；150V≤Y2≤300V，Allowable peak pulse voltage＞5KV，Y4＜150V，Allowable peak pulse voltage＞2.5KV

Different circuits choose safety capacitors with different withstand voltage values, which cannot be too large or too small. For X capacitors, X2 capacitors are often used.

2、Authentication type

No matter what component it is, as long as it is formal, it must be certified. Safety certification also includes product safety certification, environmental certification, and energy certification. Different countries have different safety regulations, and some stipulate compulsory certification. There are many certifications, such as China CQC certification, Germany VDE certification, UL certification in the United States, ENEC certification in the European Union, KC certification in South Korea, etc. When choosing safety capacitors, different certified components should be selected according to different occasions and countries.