Sustained overvoltage is a power quality issue impacting both network and customer equipment. Previous research which has investigated the impacts of instantaneous over-voltage, neglected the accelerated degradation that may be occurring due to sustained voltages at the upper end of the allowable range. The project described in this paper involved significant testing to investigate the impact that sustained overvoltages may have on customer equipment. It is well known that most electronic equipment is now supplied by Switch Mode Power Supplies (SMPS). Literature suggests that the most common cause of failure for these devices is the breakdown of electrolytic capacitors which can be particularly sensitive to supplied voltage. In order to examine the impact of input voltage on SMPS lifespan, a specially designed test device was built to represent a simple SMPS. . It was found that as capacitors degrade, a decrease in capacitance and increase in equivalent series resistance (ESR) can be observed. Based on test results, product lifecycle management software was used to determine the failure model and acceleration factor resultant due to the operating voltage.

Overwhelmingly, the result of the testing revealed that the input voltage had a significant impact on the capacitor's expected lifetime. Operating at a voltage level of 250 V for example results in an acceleration factor of 1.3; a significant reduction in operating lifetime. Expressed another way, a SMPS supplied at 250 V can only be expected to last approximately 77% as long as the same device supplied at rated voltage. The work is a step toward better understanding of the impact of supply voltage on equipment connected to distribution networks. Further study is required to determine the impact of supply voltage on different types of equipment and under different operating scenarios.