External charging circuit for static switch

摘要

A static switch including main and auxiliary SCR's has a commutating capacitor coupled between the common connections of these main and auxiliary SCR's. An independent external charging circuit is provided and connected to complete a charging path for the commutating capacitor which is isolated by at least one diode from the main d-c bus. This enables the commutating capacitor to charge to a level above that of the d-c bus voltage and maintain effective commutation.