Improve efficiently soft-starter transients´ immunity

In this paper the authors present results of measurements and mathematical analysis on MV Silicon Controlled Rectifiers (SCR, Thyristors) for the purposes of the power electronics components protection during turn on. Current transient was identified as responsible for damaging soft-starters in field applications. This work is focused on the identification of the major parameters playing role in the current transient. Formulae for calculating the current rate-of-rise and risk identification procedure are derived. A simple tool for practical SCR transient protection design is described.