【description】：in the dc part of the main circuit, aluminum electrolytic capacitors with large capacity are used as filters, and their characteristics will deteriorate due to the influence of pulsating current.
in the dc part of the main circuit, aluminum electrolytic
capacitors with large capacity are used as filters, and their characteristics will deteriorate due to the influence of pulsating current. the deterioration is greatly affected by the ambient temperature and service conditions. when it is used in the general environment with air conditioning, it should be replaced in about 5 years.
the deterioration of capacitors develops rapidly after a certain period of time, so the inspection cycle is generally one year, and it is better to be less than half a year when approaching the service life. the judgment method of appearance during inspection is as follows:
1) state of shell: expansion degree of shell side and bottom.
2) condition of sealing plate: obvious bending, serious crack.
3) status of explosion-proof valve: the expansion of the valve is significant and has been activated.
4) others: cracks, discoloration and leakage on the surface. if it is found that the upper electrode mounting plate of the capacitor expands and cracks appear, and the upper temperature rises by more than 15k, it should be replaced immediately. if the capacitor is placed unused for a long time, its leakage current will increase. if the voltage is applied sharply, it may be damaged due to the temperature rise. therefore, it is necessary to add about 1 / 2 of the rated dc voltage before use, and then use it according to the rated value after aging for more than 30 minutes and reducing the leakage current.
