METHOD FOR IDENTIFYING CAUSE OF CIRCUIT BREAKER OFF-OPERATION Russian patent published in 1997 - IPC

FIELD: protection of contact systems, such as those of trams and trolleybuses. SUBSTANCE: voltage across power feeder of contact system is pre-recorded during transients occurring in case of short circuits or overloads in line. Then two reference voltages of opposite polarity are shaped depending on amplitude of transient in line under short-circuit and overload conditions and compared with voltage across power feeder. In case of circuit breaker opening, comparison is made within at least one decay period of power feeder voltage. In the action, signal differences are shaped which are used for shaping emergency condition signal. EFFECT: facilitated identification of cause of circuit breaker opening causing open circuit in power feeder of urban transport contact system; improved validity of information supplied. 3 dwg