INSTANTANEOUS FAULT PROTECTION ALGORITHM FOR MICROPROCESSOR BASED ELECTRONIC TRIP UNITS TO AVOID NUISANCE TRIPPING OF CIRCUIT BREAKER

摘要

The present invention provides an instantaneous fault protection algorithm for microprocessor based electronic trip units adapted to avoid tripping of the circuit breaker under the conditions of nuisance or unwanted signals. The fault protection mechanism comprises a trip unit that receives a plurality of analog signals from a respective plurality of current sensors of the respective current phases. The fault protection mechanism includes a microcontroller that performs essential computations for providing a digital root mean square value for corresponding plurality of analog instantaneous fault protection algorithms. The fault protection mechanism includes a trip function block having an electromechanical trip solenoid adapted that receives the trip signal from the microcontroller and discontinues a supply for providing protection against a fault condition and/or a nuisance signal.