Congruence of low voltage power main transient designs

It is argued that the conditions and problems for high-voltage protection in the 1920s to 1940s are similar to those prevailing today for low-voltage (under 1000 V RMS) power system transient protection. Data are now being collected beyond voltage crest values vs. occurrence rate such as: waveshape epoch, rate of rise, ringing periods, energy, and energy spectral density. Protection design is complicated by the wide diversity of equipment designs which are installed, differing site conditions, and the effects of load on the power main distribution with transients ranging from electrically fast nanosecond duration to very long duration. Since no present standard can adequately test for these transients, low-voltage transient protection standards are being revised. The updating of the database and equipment testing can result in better cost-effective surge protection