16
3. Protection functions
Power XPert® release triP unit for MagnuM PXr circuit breakers
MN013015EN January 2022 www.eaton.com
Figure 13. Verifying ZSI operation.
Then feeder 11 is tested with 4000 A of secondary injec-
tion current to simulate a fault above its short delay pickup
setting. Feeder 11 shows a checkmark because it is self-
interlocked. Main 1 breaker shows a checkmark, so it has
received the ZSI input signal.
Feeders 12 and 13 are in the same zone and did not see the
fault (the simulated fault is on feeder 11) and should not see
the ZSI input signal. Feeder 12 will not show a checkmark,
which is correct. But feeder 13 shows a checkmark. Further
inspection will find that feeder 13 has its input and output
signals wired incorrectly.
Additional information on ZSI can be found in the Eaton appli-
cation note: AP02602002E.
3.10 Making current release (MCR)
All PXR trip unit styles have a making current release (MCR)
function. This safety feature prevents the circuit breaker
from being closed and latched-in on a faulted circuit. The
MCR is enabled only for the first two cycles of current
following the initial circuit breaker closing operation. The
circuit breaker will trip with no delay and the instantaneous
(INST) indicator will show the cause of trip. This non-adjust-
able release is set at the factory based on the sensors and
frame of the circuit breaker.
