Laboratory tests of electrical appliances immunity to voltage swells

In Norway there has during the last 20 years been verified a trend of more damage to electrical appliances in general and electronic equipment in particular. This has been believed to be caused by cheaper and poorer electrical appliances but also increased voltage levels and levels of voltage swells to some of the customers in the low voltage network. The latter has partly been caused by stronger economic regulation of the Norwegian electric power network that has amongst others led to stronger utilization of the distribution network. Instead of strengthening the low voltage network with increasing load, many Utilities tend to step up the transformer and introduce larger voltage variations from the transformer LV busbar to the far end of the LV feeders. The paper describes the laboratory tests recently performed by SINTEF Energy Research of common electrical appliances immunity to voltage swells. Test procedure and test results are presented in the paper. A total of 62 electric appliances were tested for immunity against voltages swells until damages occurred or the maximum output voltage from the test generator of 230 V + 40 % was reached. Many of the tested 230V electrical appliances (television sets, computers, computer screens, music systems etc) are able to handle relatively severe voltage swells, 40 % overvoltage for up to 100 seconds.