I am looking for a description of advanced 3-phase circuit protection. In particular, I hear there are devices that will detect a missing phase and drop cut the circuit immediately (in one cycle), even though the general overcurrent protection has a time delay. I would like to know exactly what the criteria are for detecting a missing phase (based on current I guess), and if there are any other intelligent breakers out there.

Robert Scott

 

Try googling "phase loss relay". Should get many hits. Square D, etc.