A: The poor quality of electrolytic capacitor has the following characteristics: leakage of liquid, high leakage current, high loss, heating, bulging, cracking, combustion caused by explosion, capacity reduction, and increase of internal resistance and inductance. For the filter electrolytic capacitor, because of its high voltage, large capacity and large energy, it is easy to cause leakage, explosion and combustion. Electrolyte is combustible and can cause combustion accident. Therefore, it is necessary to use a good quality electrolytic capacitor and replace it with a new one before reaching its service life.