zog
Senior Member
- Location
- Charlotte, NC
Don't have the details for the Micrologic 6.0A but this is (One of and most common) GF sensing schemes (Residual) used by Siemens in thier STIII trip unit.
Under normal system conditions, (without the presence of a ground fault) the vector sum
of the phase currents being monitored by the trip unit is zero. This is also true under the condition of an overcurrent phaseto- phase fault and phase unbalance condition. When a
phase-to-ground fault occurs, the vector sum of the phase currents is directly proportional to the magnitude of the ground fault. The trip unit?s microprocessor uses this vector
sum data in the execution of the ground fault protection function. The trip unit utilizes the internal breaker current sensors. No external current sensors are required.
Under normal system conditions, (without the presence of a ground fault) the vector sum
of the phase currents being monitored by the trip unit is zero. This is also true under the condition of an overcurrent phaseto- phase fault and phase unbalance condition. When a
phase-to-ground fault occurs, the vector sum of the phase currents is directly proportional to the magnitude of the ground fault. The trip unit?s microprocessor uses this vector
sum data in the execution of the ground fault protection function. The trip unit utilizes the internal breaker current sensors. No external current sensors are required.