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Y vs. X Templates
Y vs. X Templates contain a set of Y measurement limits for a range of X
measurement values; the measurement value, Y, should
be within a known upper and lower limit at a specific value of X. The template limit
profile may be different for each event if the behavior of the X
measurement changes between events.
Y vs. X templates are used when the
desired Y measurement value is not based on "time-into-event", but
is based on the current value of another measurement
value (X).
Example:
The template below contains a set of
limits for a temperature measurement (Y) for a range of pressure
values (X) during the event. The 3 traces are:
Red: Upper limit
Green: Center line
Blue: Lower limit
Template
limits (Y vs. X)
When an event is active, the
temperature measurement value (Y) will be compared to the template limits in
real-time, storing the current state (high limit violation,
compliant, low limit violation) in an alarm point on the PI Server
(digital tag). The current temperature limits are based on the current pressure
reading. The user can also perform analysis of historical
measurement values (during completed events) versus the template
limits.
The trend below shows the temperature (black
trace) versus the template limits during an event. For this event,
the temperature was within the template for most of the event, with
an obvious violation occurring when the pressure was near 270. The current alarm state
of the temperature versus the limits is stored in a digital alarm
tag on the PI Server.
Template
limits and measurement value during an event
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