Points to note when choosing X capacitors
1. Capacitors for suppressing electromagnetic interference of power supply
When capacitors are used to eliminate noise in power cross-line circuits, not only normal voltages, but also abnormal pulse voltages (such as lightning) must be considered, which may cause the capacitors to smoke or catch fire. Therefore, the safety standards for cross-line capacitors are strictly regulated in different countries, so safety-certified capacitors must be used.
2. It is not allowed to use DC capacitors as cross-line capacitors:
The X2 type capacitor for suppressing electromagnetic interference of power supply should be suitable for occasions that will not cause electric shock when the capacitor fails, such as the power supply is connected across the line, which can withstand 2.5kV pulse voltage.
The Y2 capacitor for suppressing power supply electromagnetic interference should be suitable for occasions that will not cause electric shock when the capacitor fails. When the power supply is connected across the line, it can withstand 5kV pulse voltage impact without causing breakdown.
1. X capacitors, polystyrene (film vinyl) capacitors, and polystyrene have higher voltage resistance and are suitable for high-voltage pulse absorption in EMI circuits.
2. Capacity calculation: Generally, two-stage X capacitors, 0.47uF for the first stage and 0.1uF for the second base; 0.47uF for single-stage. There is no convenient calculation method yet. (The size of the capacitance is not directly related to the power of the power supply)
X capacitors refer to peak voltages, not rated voltages. X capacitors generally use MPX (Metalized Polypropylene Molded Capacitors) whose rated voltage is also several hundred volts. For example, a kind of X2 is marked as MPX-X2-250VAC/275VAC.