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Maintenance, testing, and operating conditions
MAGNUM PXR PRODUCT GUIDE
PA013006EN September 2022 www.eaton.com
6
Breaker health monitoring
All Magnum circuit breakers have had an excellent service
utilization record. The traditional challenge has been deter-
mining when circuit breakers, need to be removed from
service, or need required maintenance.
Figure 80
shows
the typical “bathtub” failure curve. The important aspect
of circuit breaker health to determine is when the few
problems occur on the bottom of the curve and where the
wear out period begins to rise.
Environmental factors such as excessive temperature,
moisture, dust, chemical vapor, and vibration can also have
a major effect on the health of the breaker. Further, if the
circuit breaker has been in service for an extended period,
has not been properly maintained, and subjected to exces-
sive environmental and overcurrent conditions, it is difficult
to know with confidence that the device can perform its
intended functions.
When a circuit breaker interrupts a high-level fault current
at or near the device interrupting rating, there traditionally
was not a straightforward way to determine if the circuit
breaker that cleared the fault would be able to continue
to protect the system. The internal damage that occurs
during repeated fault current interruption could impact
the breaker’s ability to interrupt a future fault – potentially
compromising future performance.
Figure 80. Typical bathtub failure curve
Eaton’s Power Xpert
®
Release (PXR) trip units make a step
change improvement over traditional breaker inspection
procedures, as they provide powerful data analytics and
predictive diagnostics for low voltage circuit breakers. This
critical information can be used to make more informed
decisions about actual equipment conditions. These intel-
ligent circuit breakers can display an easy-to-understand
data summary of the breaker’s full health that can be
easily leveraged by a customer or maintenance person.
Figure 81. PXR with graphic of health summary
The parameters that are monitored by Eaton’s PXR trip
units include short circuits, overloads, operations, tempera-
ture, and run-time. These parameters can provide a host
of individual insights while the combination of all of them
provide an overall picture of the condition of the breaker
that can be used for predictive maintenance and system
reliability. Specific insights include:
Operation data
provides insight on when the breaker
mechanism was last exercised, and if the mechanism was
bound or jammed.
Total number of operations
can provide indication of the
endurance wear on the circuit breaker mechanism and
indication of contact wear.
Number of interruptions
, and the magnitude of the
energy interrupted, are vital parameters to the contact
wear indication and the arc chute condition.
Overload interruptions
have less of an effect than short-
circuits, but they are included in the calculation and weigh
in on the health.
Short circuits
can be damaging to the contacts, integrity
and dielectric strength of the circuit breaker. The magni-
tude of a short-circuit event is compared to the rating of
the circuit breaker and weighed as another factor in the
health of the circuit breaker.
Run-time
is also considered and demonstrates how long
the breaker has been in use with current flowing through
it.
Environmental temperature
is one of the most important
measurements; this is the highest temperature recorded
and the date and time of that temperature is saved in the
analysis.