The most comprehensive analysis of X/Y safety capacitors in power supply filtering (II)

The X capacitor, which is one of the safety capacitors, is also required to be certified by a safety inspection mechanism. X capacitors are generally marked with a safety certification mark and withstand voltage AC250V or AC275V, but its true DC withstand voltage is as high as 2000V or more. When using it, do not use the ordinary capacitors such as AC250V or DC400V at random.

In general, X-capacitors are often made of a polyester film-type capacitor with a large ripple current. This type of capacitor is bulky, but it allows a large amount of current to be instantaneously charged and discharged, and its internal resistance is correspondingly small. The common capacitor ripple current has a low index and a high dynamic internal resistance. Replacing the X capacitor with a common capacitor, in addition to the capacitor withstand voltage can not meet the standard, the ripple current index is also difficult to meet the requirements.

According to IEC 60384-14, capacitors are divided into X capacitors and Y capacitors:

1. X capacitor refers to a capacitor across the L-N;

2. Y capacitor refers to a capacitor across L-G/N-G;

(L=Line, N=Neutral, G=Ground)

The X capacitor is further divided into X1, X2, and X3. The main differences are:

1. X1 withstand voltage is greater than 2.5 kV, less than or equal to 4 kV;

2. X2 high pressure is less than or equal to 2.5 kV;

3. X3 high pressure is less than or equal to 1.2 kV

The Y capacitor is divided into Y1, Y2, Y3, and Y4. The main differences are: (DC voltage resistance)

1. Y1 high pressure is greater than 8 kV;

2. Y2 high pressure is greater than 5 kV;

3. Y3 high pressure n/a

4. Y4 high pressure resistance is greater than 2.5 kV

They are used in the power supply filter to filter the power supply and filter the common mode and differential mode interference.