Surge immunity of electronic equipment

There was a tentative test of 20 video recorders at Darmstadt University of Technology with respect to the withstand capability against transient overvoltages. Transient overvoltages are a common phenomenon in low-voltage-installations. Most of these events originate from switching operations of other equipment or blowing of fuses. Depending on the location atmospheric events may contribute to the overvoltage stress. The main goal of the test was to obtain information about the practical performance of consumer electronic equipment in normal use. Consequently the tests were performed taking into account the IEC-requirements with respect to electromagnetic compatibility (surge immunity). The test levels were chosen according to the requirements with respect to insulation coordination (overvoltage category II). Only 7 of the sample with 20 video recorders passed the test without any failure. Almost all failures observed were located in the primary part of the power supply. Typically, the radio interference suppression capacitors failed and/or internal fuses were blowing. Although the damage is rather small and limited to a few components, a rather expensive repair is required in any case.