State condition estimation of aluminum electrolytic capacitors used on the primary side of ATX power supplies

This paper presents a very simple fault diagnostic technique, that is able to evaluate the state condition of aluminum electrolytic capacitors used on the primary side of ATX power supplies. These capacitors have a high failure rate due to wear-out degradation failure, representing one of the weakest components of this equipment. Many times the ageing of these capacitors leads to the destruction of other components, like switch-mode transistors. The ageing of aluminum electrolytic capacitors is expressed by the increase of their internal resistance. The proposed fault diagnostic technique is based on the estimation of capacitors internal resistance in order to evaluate the capacitors state condition. To do so, a discrete Fourier algorithm is used. The temperature effect is also considered.