Short-circuit protection of GTO thyristor pulse inverter - allows conduction through intermediate circuit fuse during first half-cycle only before blocking at zero current

摘要

The three gate conditions of a gate turn-off thyristor (GTO) are realisable by a control circuit with a control input (ST) to a three -position switch (S). In position (1) a DC source (U1) delivers a postive firing current to the gate (G), causing conduction from cathode (K) to anode (A). In position (2) the thyristor is biased off by an inverse DC voltage (U2). In position (3) a low resistance (R) extinguishes the anode current automatically at a zero-crossing. ADVANTAGE - Thyristor is not damaged either by internal or external short-circuits, and only intermediate circuit fuse is blown.