Y capacitor is also one of the safety capacitors and a unique device in power circuits, especially in AC/DC converters where Y capacitor plays a significant role in suppressing common mode interference.
The Y capacitor is divided into Y1 capacitor and Y2 capacitor. Y1 belongs to the double insulated Y capacitor and is used for bridging the primary and secondary sides. Y2 belongs to the basic single insulated Y capacitor. Used for bridging the primary side to protect the ground, i.e. FG line, according to IEC 60384-14.
Under the Y capacitor, it is further divided into Y1; Y2; Y3; Y4, the main difference is that Y1 can withstand high voltage greater than 8 kV; 2Y2 withstand high voltage greater than 5 kV,; Y3 high voltage resistance n/a 4; Y4 has a high voltage resistance greater than 2.5 kV.
X capacitor is a capacitor that spans between two lines (L-N) of a power line. Generally, metal thin film capacitors are chosen because metalized thin film capacitors have a large volume, but they allow for a large instantaneous charge and discharge current, and their internal resistance is correspondingly small.
The X capacitor is connected across the neutral and live lines of the power supply, and requires a high voltage withstand value. The voltage withstand levels of X1 and X2 capacitors are different: X1>2.5kV ≤ 4.0kV; X2 ≤ 2.5kV.
We see on the products of Y capacitor, whether it is Y1 capacitor or Y2 capacitor, there is a lettering label X1 400V on the products. Why is this?
The X capacitor is the identification code for the Y capacitor. When applying, Y capacitors are paired with X1 as a series. It is not easy to generate electric shock when the safety capacitor fails. Y capacitor and X1 capacitor can be assembled into components that can withstand applied voltage and achieve better insulation performance.