West Control Solutions N8100 - Manual (Page 21)

2.2.22 Deviation (High/Low) Alarm 1 Value
This parameter, applicable only if Alarm 1 is selected to be a Deviation High/Low
Alarm, defines a value above (positive value - Deviation High alarm) or below
(negative value - Deviation Low alarm) the setpoint; if the process variable
deviates from the setpoint by a margin greater than that defined by this
parameter, Alarm 1 goes active. The operation of Deviation Alarms is illustrated in
Figure 2-3.
2.2.23 Process High Alarm 2 Value
This parameter, applicable only when Alarm 2 is selected to be a Process High
alarm, defines the process variable value at or above which Alarm 2 will be
active. The operation of a process high alarm is illustrated in Figure 2-3.
2.2.24 Process Low Alarm 2 Value
This parameter, applicable only when Alarm 2 is selected to be a Process Low
alarm, defines the process variable value at or below which Alarm 2 will be
active. The operation of a process low alarm is illustrated in Figure 2-3.
2.2.25 Band Alarm 2 Value
This parameter, applicable only if Alarm 2 is selected to be a Band Alarm, defines
a band of process variable values, centred on the setpoint value. If the process
variable value is outside this band, the alarm will be active. The operation of a
band alarm is illustrated in Figure 2-3.
2.2.26 Deviation (High/Low) Alarm 2 Value
This parameter, applicable only if Alarm 2 is selected to be a Deviation High/Low
Alarm, defines a value above (positive value - Deviation High alarm) or below
(negative value - Deviation Low alarm) the setpoint; if the process variable
deviates from the setpoint by a margin greater than that defined by this
parameter, Alarm 2 goes active. The operation of Deviation Alarms is illustrated in
Figure 2-3.
2.2.27 Loop Alarm Enable
This parameter is the means by which the user can enable or disable the Loop
Alarm. The Loop Alarm is a special alarm which detects faults in the control
feedback loop by continuously monitoring process variable response to the
control output(s).
The Loop Alarm facility, when enabled, repeatedly checks the control output(s) for
saturation i.e. either or both outputs being at the maximum or minimum limit. If an
output is found to be in saturation, the Loop Alarm facility starts a timer; thereafter,
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