West Control Solutions N6600 - Manual (Page 24)

3.2.8 Rate (Derivative Time Constant)
This parameter is adjustable in the range 00 seconds to 99 minutes 59 seconds.
This parameter is not applicable if Proportional Band 1 (see Subsection 3.2.5) is set
to 0 (ON/OFF control).
3.2.9 Overlap/Deadband
This defines the portion of the Proportional Band (Proportional Band 1 +
Proportional Band 2) over which both outputs are active (or, in the case of a
deadband, neither output is active). It is adjustable within the range –20% to
+20% (negative value = deadband). The default value is 0%. The function of the
overlap/deadband is illustrated in Figure 3-1. This parameter is not applicable if
Proportional Band 1 = 0 or if Output 2 is not fitted.
Note that, with Output 2 set to ON/OFF control (Figure 3-1 Case 3), the
Overlap/Deadband parameter has the effect of moving the ON Differential band
of Output 2 to create an overlap (positive values) or a deadband (negative
values). When Overlap/Deadband = 0, the “Output 2 OFF” edge of the Output 2
ON/OFF Differential band coincides with the point at which Output 1 reaches 0%.
3.2.10 Bias (Manual Reset)
This bias to the output power is expressed as a percentage of output power and is
adjustable in the range 0% to 100% (if only Output 1 is fitted) or –100% to +100%
(if both outputs are fitted). Its default value is 25%. This parameter is not
applicable if Proportional Band 1 = 0.
3.2.11 ON/OFF Differential (Hysteresis)
This is a switching differential used when one or both outputs have been set to
ON/OFF control (i.e. Proportional Band 1 or Proportional Band 2 or both = 0). This
parameter may be adjusted within the range 0.1% to 10.0% of the input span of
the Controller. The default value is 0.5%.
3.2.12 Setpoint High Limit
This is the maximum limit for setpoint adjustment. It should be set to a value which
prevents the setpoint being given a value which will cause damage to the
process being controlled. The Setpoint High Limit may be adjusted between the
current setpoint value and Input Range Maximum. The default value is Input
Range Maximum.
3.2.13 Setpoint Low Limit
This is the minimum limit for setpoint adjustment. It should be set to a value which
prevents the setpoint being given a value which will cause damage to the
3-8 O075-3
PM-0075