Honeywell Experion LX Operator's Manual page 209

Displaying detailed process information
Item
Subpriority
Deadband
Unreasonable
Value Alarm
Control Failure Alarms
PV Control
Fail Alarm
Control
Timeout
Control Dead-
band
External Change Alarms
PV
Set point
Honeywell 2017
Description
priority of 15 will be shown as critical priority alarms on the Alarm Summary and
other displays. For information about how to enable critical alarms, see
"Customizing alarm colors" in the Station Configuration Guide.
The optional sub-priority level of the alarm, between 0 (lowest and default) and 15
(highest).
You can specify a percentage value that is used in determining what constitutes a
good control. This is called control deadband. A control deadband works as fol-
lows. If the PV signal, read back after an SP control is issued, does not reach the
following value within the period specified for the Control Timeout option, a PV
Fail alarm is generated: New SP Value \± Deadband Percentage This check is per-
formed every 10 seconds (from when the control is performed) until good control
has been achieved or the control timeout period has elapsed (whichever happens
first).
The On Delay, Off Delay, Priority, and Subpriority values for the unreasonable
value alarm.
The high and low limits for unreasonable values are defined on Point Processing
tab on the Message & Point Processing display. The values are entered as a
percentage of the point range.
The Priority and Subpriority values for the PV control fail alarm.
The maximum time (in seconds) allowed, after a change in SP or OP, for the PV
value to reach an acceptable value before a control fail alarm is raised. The
default is None (no control timeout).
The server checks the value every 10 seconds during the timeout period.
You must specify a value other than Nil to enable the control fail alarm.
The percentage deviation from the SP value that constitutes a good control. (The
default value is 1.000%.) The value is calculated using the formula:
(new SP value) +/- (control deadband percentage) If the PV value is not within the
target range, a PV fail alarm is raised.
When selected, an alarm is raised if the PV parameter changes without the
change being initiated from the server.
When selected, an alarm is raised if the PV parameter changes without the
change being initiated from the server.
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