Switching power supply burst capacitor cause!

Switching power supply main filter electrolytic capacitors sometimes inexplicably explode, even if the capacitor has not exploded, it can be found that the top of the aluminum shell caused serious deformation and a drum arch. This kind of problem, the greater probability is that the input end electrolytic capacitor, and is the polarity inserted backwards, will explode so quickly, otherwise the working voltage exceeds some will not be so fast. Because of the basic cause of switching power supply electrolytic capacitor explosion.

1) is the voltage far exceeds the fixed voltage;

2) The polarity is reversed (this, in the state of low voltage will not be performed for a short time, if the input end, if the input voltage is 220V, the peak voltage after rectification is 311V, at this time if the polarity is reversed, the power will soon explode). Of course, if it is the output, the control circuit is completely out of control, so that the output voltage is out of control and a lot of overvoltage may explode. After replacing the capacitor, the direct explosion on the power is caused by the positive and negative electrode of the capacitor;

3) Insufficient voltage resistance: The capacitor explosion in use is caused by insufficient capacitance value, or insufficient voltage resistance value, substandard quality, and obvious external extrusion.

So to sum up:

1) It is most likely that the polarity of the input filter electrolysis is reversed.

2) If the capacitor is wrong, the output filter capacitor is plugged into the input end (the general switching power supply is the output DC low voltage).

3) The output voltage is completely out of control, resulting in the explosion of the filter electrolytic capacitor.

Another is that the environment is overheating, so it must be in line with the voltage, the correct polarity connection. If the ambient temperature is too high, a high temperature resistant capacitor must be used. If blasting occurs after replacing the capacitor correctly, check whether the corresponding power supply voltage is overvoltage.

In addition, qualified manufacturers and maintenance units must also carry out very necessary special sampling tests on the bulk of the main filter electrolytic capacitors used in switching power supply.