Electronic circuit breaker

• Main Author: MERONI; UMBERTO
• Format: Patent
• Language: English
• Published: 03.04.1979
• Subjects: CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS; GENERATION

An electronic circuit breaker feeding a d-c/d-c converter from a power supply common to several such converters includes a normally saturated main or switching transistor T1 in series with the associated converter, the latter having an output from which auxiliary voltage is fed back to an ancillary transistor T2 lying in series with a voltage divider R1, R2 serving to bias the main transistor into conduction. A further transistor T3 triggers the cutoff of the main transistor T1 when the converter draws excess current, part of which flows through the voltage divider R1, R2. Another voltage divider R4+L, R5 in parallel with the first-mentioned divider biases the further transistor T3 and is thus traversed by a portion of the feedback current passing through the ancillary transistor T2, being therefore likewise cut off upon de-energization of the converter by the cessation of conduction through the main transistor. Restoration of normal conditions is possible by the temporary opening of a switch in series with the converter input whereby a capacitor C1 connected across the output of the ancillary transistor T2 is discharged so that reclosure of the switch starts a current flow through the two voltage dividers; a shunt capacitor C2 connected across the input of the trigger transistor T3 delays its conduction so that the switching transistor T1 again saturates as the converter is re-energized.