This paper presents an analysis of voltage stresses on the reactor of the MSCDN when subjected to switching surges during its routine energization. Transient voltages of high magnitude and frequency can occur at the reactor of the MSCDN after the closing of the circuit breaker at an unfavourable point-on-wave instant. Under fast transients, the stray inductances and capacitances of the reactor winding will influence the transient voltage distribution along the reactor column. In this paper, a lumped parameter equivalent circuit is developed to assess the distribution of switching surge voltages along the reactor winding. The analytical derivations of the lumped parameter circuit components used for the equivalent circuit are presented. The results indicate that high-frequency oscillatory overvoltages were generated in all sections of reactor winding. The highest voltage magnitudes with rapid rate of change were observed in particular across the top sections of the winding. These voltage stresses may exceed the impulse withstand level of the reactor insulation.
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