Nanosecond switching transients recorded in a mining transformer installation

Tests carried out on a mining power transformer supply system to determine the severity of the switching transients developed with a range of system and plant conditions are described. Results obtained with vacuum and SF/sub 6/ circuit breakers are presented and indicate that very fast transients with wavefront durations as short as 10 ns are frequently produced. An examination of the transients is made, and the system and plant parameters that lead to the production of very fast transients are identified. Wavefront duration is mainly governed by system parameters and wave amplitude by the type of circuit breaker. The relevance of the results to other types of power transformer supply systems is indicated.<>