West Control Solutions N6600 - Manual (Page 28)

3.2.22 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. This parameter value may be adjusted in the
range ± (input range) from setpoint. The default value is five input range units. The
operation of Deviation Alarms is illustrated in Figure 3-2.
3.2.23 Alarm 1 Hysteresis
This parameter applies a hysteresis band on the “safe” side of the Alarm 1 value.
Thus, Alarm 1 will become active when the Alarm 1 value is exceeded; Alarm 1
will become inactive when the process variable value is outside the hysteresis
band on the “safe” side of the Alarm 1 value. Alarm 1 Hysteresis may be set to a
value in the range 1 - 250 or 0.1 - 25.0 (as per input resolution). The effect of the
hysteresis value on the operation of the different types of alarm is illustrated in
Figure 3-3.
3.2.24 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. Its value may be adjusted between Input Range Maximum and Input
Range Minimum. Its default value is Input Range Maximum. The operation of a
process high alarm is illustrated in Figure 3-2.
3.2.25 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. Its value may be adjusted between Input Range Maximum and Input
Range Minimum. Its default value is Input Range Minimum. The operation of a
process low alarm is illustrated in Figure 3-2.
3.2.26 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. This parameter may
be adjusted to be within
± (input span) from the setpoint. The default value is five
input units. The operation of a band alarm is illustrated in Figure 3-2.
3-12 O075-3
PM-0075