Safety capacitor includes two types: X capacitor and Y capacitor. X capacitor is a capacitor that is connected between two lines of power line (L-N), and metal film capacitor is generally used. Y capacitor is a capacitor that is connected between two lines of power line and ground (L-E, N-E) separately, and usually appears in pairs.

First of all, we know that capacitors consist of two metal poles with insulating materials (dielectrics) sandwiched between them. Due to the different insulation materials, the types of capacitors are also different:

According to the structure, it can be divided into fixed capacitor, variable capacitor and fine-tuning capacitor. According to dielectric materials, they can be divided into gas dielectric capacitance, liquid dielectric capacitance, inorganic solid dielectric capacitance, organic solid dielectric capacitance and organic solid dielectric electrolytic capacitance. According to polarity, it can be divided into polar capacitor and non-polar capacitor.

Capacitance has the function of separating direct current and alternating current in circuit, so it is often used for inter-stage coupling, filtering, decoupling, bypass and signal tuning.

Safety capacitors can be divided into:

X1 >2.5kV ≤4.0kV

X2 ≤2.5kV

X3 ≤1.2kV

Matters needing attention:  

Capacitors for Suppressing EMI of Power Supply

When using capacitors to eliminate noise in power supply cross-line circuits, not only the normal voltage, but also the abnormal pulse voltage (such as lightning) must be considered, which may cause the capacitor to smoke or fire.Therefore, the safety standards of cross-line capacitors are strictly regulated in different countries, so it is necessary to use certified capacitors.