West Control Solutions N6600 - Manual (Page 30)

3.2.27 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. 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.
3.2.28 Alarm 2 Hysteresis
This parameter applies a hysteresis band on the “safe” •side of the Alarm 2 value.
Thus, Alarm 2 will become active when the Alarm 2 value is exceeded; Alarm 2
will become inactive when the process variable value is outside the hysteresis
band on the “safe” side of the Alarm 2 value. Alarm 2 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.
3.2.29 Heater Current High •Scale Limit
This parameter defines the full scale value for the heater current range. It may be
adjusted from 10.0A to 20.0A in 0.1A increments, and then from 21A to 100A in 1A
increments. The default value is 50A. Heater current range minimum is fixed at
0A. This value also determines the Short Circuit Heater Break Alarm level (see
below).
NOTE: If this parameter value is changed, the Heater Nominal Current, Low
Heater Break Alarm Value and High Heater Break Alarm Value parameters
are set to their default values (see Table 3-1).
3.2.30 Heater Nominal Current
This parameter defines a nominal value for the heater current and is only
applicable if Heater Break Alarm Strategy is configured to Percentage Mode. It
may be adjusted in the range 0A to Heater Current High Scale Limit. The default
value is the Heater Current High Scale Limit. It can also be set automatically (in
Operator Mode or Set Up Mode) to the heater current value at any instant by
using “Quick Transfer” (see Subsection 2.13).
3.2.31 Low Heater Break Alarm Value
The Controller monitors two current values: ON-current (when Output 1 is on) and
OFF-current (when Output 1 is off). This parameter defines a heater ON-current
value below which the Low Heater Break Alarm will become active. It may be
adjusted in the following ranges below the heater current nominal value:
3-14 O075-3
PM-0075