●Safety level of safety capacitors: Peak pulse voltage overvoltage level (IEC664) allowed in safety capacitor safety level application, X1 >2.5kV ≤4.0kV III, X2 ≤2.5kV II, X3 ≤1.2kV I, safety capacitor Safety class Insulation type Rated voltage range: Y1 Double or reinforced insulation ≥ 250V, Y2 Basic insulation or additional insulation ≥150V ≤250V, Y3 Basic insulation or additional insulation ≥150V ≤250V, Y4 Basic insulation or additional insulation <150V,Y capacitor The capacitance must be limited to control the amount of leakage current flowing through it at rated frequency and rated voltage and the effect on the EMC performance of the system. GJB151 specifies that the capacity of the Y capacitor should be no more than 0.1uF.
In addition to the corresponding grid voltage withstand voltage, the Y capacitor also requires sufficient safety margin for electrical and mechanical performance to avoid breakdown and short circuit under extreme environmental conditions. The pressure resistance of the Y capacitor is correct. Protecting personal safety is of great significance.
●The capacity of the safety capacitor has nothing to do with the voltage: the dielectric constant of the insulating material between the plates used in the general capacitor is a fixed value, so the capacity of the safety capacitor is independent of the voltage applied across the plates, and the safety capacitor When the voltage at both ends changes, the amount of electricity in the safety capacitor changes accordingly. The ratio is a constant of Q/U, that is, its capacitance: the change of voltage is related to the current of the safety capacitor and KVAR! As the voltage rises, the current and KVAR will increase. In the safety capacitor structure, the capacitor is composed of an insulating medium added between the two plates. The capacitance is proportional to the area of the plates and inversely proportional to the thickness of the medium. The area generally does not change, and the thickness of the medium may be thinned or weakly broken due to factors such as time ambient voltage during use, so that the capacity changes.
●The safety capacitor has a pinhole phenomenon: there is a pinhole phenomenon. Why is this? In fact, the safety capacitor has a true hole that can be used continuously without affecting the electrical performance, but it will affect the appearance. The outer layer of the safety capacitor is made by encapsulating the epoxy resin and then sintering at a high temperature. The cause of bubbles and pores in the outer envelope of the safety capacitor epoxy resin is: first, the gas in the encapsulating material, followed by the gas of the safety capacitor chip. Therefore, the epoxy encapsulant and the safety capacitor chip are vacuum treated before the impregnation.
Since there are many gases in the inside of the safety capacitor chip and the lead wire soldering, the vacuum processing is not good, and the gas expands during the heating and solidification process of the encapsulating material, so that the safety capacitor generates bubbles and pores.If the safety capacitor is vacuum-encapsulated, it is slowly solidified with the encapsulating material after being left at room temperature for a period of time. When the encapsulating material reaches a certain hardness, it is placed in the baking box to be heated and solidified, so that bubbles are not easily generated.