Monitoring circuit for pulse controlled DC load - provides binary logic sensing and control of fault condition in load or its associated FET switching device

摘要

A short circuit sensing and protection circuit, for a D.C. load (1) and its pulsed FET (T1), employs a binary logic module (5) with an input (A) from the junction of the load (1) and pulsed FET (T1) and a second input (B) from the pulse width modulated generator (3). A short circuit condition generates a signal pulse from outputs (Q1, Q2) of the logic module (5) corresp. to FET (T1) or load (1) malfunction. A control unit (4) then activates relay (2) opening its normally closed contact and isolating the system from the supply source (Vcc). USE/ADVANTAGE - Is capable of limiting short circuit duration to within half period of pulse generator. Quick response also protects supply source components, e.g., transformer and rectifiers. Can discriminate between FET and load short circuits.