Overvoltage protection circuit for DC source and load - has thyristor switch, limiting inductance and comparator logic control for limiting current surge to reservoir capacitor during transient

摘要

A method of protecting a DC source (Q) and its connected reservoir capacitor (C) and load (2) from the effects of transient overvoltage is arranged to disconnect the load (2) and capacitor (C) via thyristor (V1) during the voltage surge. Load current (IL) continuity is maintained however with inductance (L) limiting the current rise in capacitor (C) to a value within the turn off capability of thyristor (V1). A supervisory module (ii) provides a control regime using comparator logic which references the output circuit condition to a standard voltage worm. ADVANTAGE - Ensures limitation of capacitor charging current during transient, so that temporary disconnection of source is rapidly achieved within capability of thyristor switch. Maintains continuity of load supply during source disconnection. protects other loads supplied from same sources against voltage spikes caused for example by blowing of circuit fuse.