9
3 Protection setting description
PXR tRiP units foR PoweR Defense molDeD case ciRcuit bReakeRs
MN012007EN June 2018 www.eaton.com
2.5 Thermal-magnetic trip units
The Power Defense line of circuit breakers also includes thermal-magnetic trip units in
several combinations of fixed and adjustable protection. Details can be found at www.
eaton.com/powerdefense.
3 Protection setting description
The PXR trip unit protection settings are easily customized to any application. Settings
for long delay pickup, long delay time, short delay pickup, short delay time, instantaneous
pickup, ground fault pickup, and ground fault time are all configurable. These functions are
set using PXPM software, or rotary switches or the UI on the front of the trip unit.
Maximum and minimum settings will vary by trip unit style and breaker frame. A summary
of the available settings by PXR model and breaker frame is shown in Section 1.1, please
consult the detailed tables within Section 9: Available protection settings.
Before placing any circuit breaker in operation, set each trip unit protection setting to the
values specified by the engineer responsible for the installation.
3.1 Long delay pickup and time setting
The PXR trip unit offers a wide range of settings for long delay pickup (LDPU or I
r
). The
actual pickup value for long delay will be 110% of the set point value with a +/- 5% tolerance
to ensure that the circuit breaker can carry the full rating of (I
r
), without tripping.
The long delay time setting value represents the clearing times when the current value
equals six times (I
r
). All times are referenced from the top of the tolerance band, ensuring
that the time never exceeds that maximum setting.
I
r
is also the base for the short delay current setting.
3.1.1 Long delay slope selection
The I
2
t setting is the factory default curve for long delay. Certain styles of trip unit offer
other slope selections. The curve can be changed using PXPM software or the UI to better
match application requirements for protection and coordination.
•
I
2
t - Inverse time current curve, used in standard distribution protection (factory default).
•
I
4
t - Extremely inverse time current curve, for coordination with fuses or special types of
loads.
