Y vs. Time Templates

Y vs. Time Templates contain a set of measurement limits at “time into event”; the measurement value should be within a known upper and lower limit at time X into the event. The template limit profile is the same for each occurrence of the event.

Example:

The template below contains a set of limits for a level measurement during the event. The 3 traces are:

Red: Upper limitGreen: Center line | Blue: Lower limit

Template limits (Y vs. Time)

yvstime_level

When an event is active, the level measurement value will be compared to the template limits in real-time, storing the current alarm state (high limit violation, compliant, low limit violation) in an alarm point on the PI Server (digital tag). The user can also perform analysis of historical measurement values (during completed events) versus the template limits.

The trend below shows the level (black trace) versus the template limits during an event. For this event, the level value was close to, or above, the upper limit during the entire event. The current alarm state is stored in a digital alarm tag on the PI Server.

Template limits and measurement value during an event

yvstime_level_measurement

 

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)

yvsx_template

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

yvsx_measurement