The full name of X capacitor is generally called X2, X1, X3 or MKP capacitor for power EMI suppression. Functions in the circuit: power supply cross line circuit, EMI filtering, spark elimination circuit, etc., to ensure that the finished electronic products meet EMC requirements.
Capacitors are divided into X capacitors and Y capacitors. The X capacitors are between the live line and the neutral line. The X capacitor is used in power filter to filter power supply and differential mode interference. The capacitance in parallel between the live line and the neutral line suppression is generally called X capacitance.
As the location of this capacitor connection is also critical, it also needs to comply with safety standards. Therefore, X capacitor is also one of the safe capacitors.
The capacitance value of capacitance X is allowed to be larger than that of capacitance Y, but a safety resistance must be connected in parallel at both ends of capacitance X to prevent the power cord plug from being electrified for a long time due to the charging and discharging process of the capacitance when the power cord is unplugged.
According to the safety standard, when the machine power cord is unplugged, the live voltage or ground potential at both ends of the power cord plug must be less than 30% of the original rated working voltage within two seconds.
1. Capacitance Tolerance.
The capacitance tolerance of X2 safety class capacitor is relatively large, which is generally of class K, that is, ± 10% capacitance tolerance. Its capacity accuracy is not as high as that of commonly used film capacitors.
2. Rated voltage.
The rated voltage of X2 safety capacitor is not fixed. The rated voltage of X2 safety capacitor varies from manufacturer to manufacturer. If the working voltage exceeds the withstand voltage of safety capacitor, the safety capacitor will break down and be easily damaged.
275V is the minimum rated voltage, 275V/305V/310V is the middle rated voltage on the market, and 310V/350V/380V is the rated voltage of high-quality X2 safety capacitor. Generally, the higher the rated voltage is, the more sufficient the withstand voltage margin is, and the stability and life of X2 safety capacitor will be better.
3. Temperature resistance.
X2 safety capacitor is very afraid of high temperature. Generally, the higher the temperature is, the shorter its life will be. Under normal circumstances, the high temperature resistance of X2 capacitor is 110 ℃, but it should be noted that some low-quality X2 capacitors can only withstand 85 ℃. It should be noted that the higher the temperature resistance of X2 safety capacitor is, the better.
4. Certification.
For X2 safety capacitor, the more certifications it has passed, the better. The certifications that must be obtained include CQC in China, UL in the United States, ENEC in the European Union, and certifications from some small countries, such as KC in South Korea.
Main functions of X2 safety capacitor:
1. It is used for power supply cross line noise reduction and interference suppression circuit and AC occasions.
2. Electric instruments and electronic equipment powered by power grid, switches, contacts and other parts that generate spark discharge.
3. Electric tools, lighting, wind pipes, water heaters and other household appliances.
