Rockwell Automation Publication 750-RM100A-EN-P - August 2019 41
Predictive Maintenance Chapter 6
Monitor Elapsed Life and
Remaining Life
There is an elapsed life and a remaining life parameter for each component that is
covered by predictive maintenance.
Elapsed Life
The values of these parameters represent the accumulated damage that the
components experience.
The unit of measure is unique for each type of component.
•
Hours for fans, bus capacitors, and filter capacitors.
•
Cycles for relay contacts, IGBTs, precharge contactors, switches, and
breakers.
The values reflect the runtime on the components and the running conditions.
For example, elapsed life values for fans increment faster when the temperature is
higher and the fan speed is higher. Elapsed life values for IGBTs increment faster
when temperature, load, and carrier frequency are higher. Elapsed life values for
bus capacitors increment faster when temperature, load, and DC bus ripple are
higher.
Remaining Life
The value of this parameter represents a prediction of how much life is remaining
in the component. Changes you make to the event level for each predictive
maintenance function directly affect this value.
The unit of measure for these parameters is always hours, regardless of the
component type. Measuring time in hours helps you schedule replacement during
planned downtime.
Predicted values are based on the rate of change of accumulated damage. For
example, remaining life values for fans are lower when recent temperature and
speed are higher. Remaining life values for IGBTs are lower when recent
temperature, load, and carrier frequency are higher. Remaining life values for bus
capacitors are lower when recent temperature, load, and DC bus ripple are higher.
These predicted values are similar to the ‘fuel range’ displayed on many
automotive dashboards. The value is high, for a given amount of fuel, when you
are cruising efficiently on the highway. It is low, for the same amount, if you are
stuck in ‘stop and go’ city traffic.
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