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CONTROL CONFIGURATION SUB-MENU SCREENS
PID Set Selection
Choose to use one of five PID Sets; or choose Gain Schedule on SP or PV. –
This selects a fixed PID set to be “Active”; or automatically switch sets based
changes in SP or PV values.
Set n – Primary Pb
The primary proportional band for PID Set n (n = up to 5). Set as On-Off con-
trol, or a proportional band from 1 to 9999 display units – Only the set(s) in use
are shown.
Set n – Secondary Pb
The secondary proportional band for PID Set n (n = up to 5) if dual control is
used. Set as On-Off control, or a proportional band from 1 to 9999 display
units – Only the set(s) in use are shown.
Set n – Integral
The integral time value (Automatic Reset) for PID Set n (n = up to 5). Adjustable
from 1s to 99min 59s or OFF – Only the set(s) in use shown.
Set n – Derivative
The derivative time value (Rate) for PID Set n (n = up to 5). Adjustable from 1s
to 99 min 59s or OFF – Only the set(s) in use are shown.
Set n – Overlap
The overlap (+ve) or deadband (-ve) between primary & secondary propor-
tional bands for PID Set n (n = up to 5). In display units - limited to 20% of the
combined primary & secondary prop band width.
Set n – On/Off Diff
The on-off control hysteresis (deadband) for PID Set n (n = up to 5). Adjustable
from 1 to 300 display units, centred about the setpoint – Only the set(s) in use
are shown.
Set n - Breakpoint
The SP or PV value where the PID Set n (n = up to 5) if gain scheduling is used.
Set 1 is used from Scaled Input Lower Limit to the Set 2 Breakpoint, then Set
2 used to the Set 3 Breakpoint etc. If a breakpoint is set to OFF subsequent
PID sets are not used. The final PID set runs to the Scaled Input Upper Limit.
Manual Reset (Bias)
The Manual Reset value to bias the control working point within the propor-
tional band(s). Adjustable from 0 to 100% for single control or 100 to +100%
for dual control. Typically set to 80% of typical power needed for setpoint, but
lower values can help inhibit start-up overshoot.
Anti Wind-Up Limit
Adjusts the value at which the “reset wind-up inhibit” is applied. Above this
power level further integral action is suspended. Adjustable from 10 to 100%
of PID power. Lower values inhibit overshoot.
Caution:
If set too low control deviation can occur (the process set-
tles, but is offset above or below the setpoint). It this is observed,
increase the value until the deviation error is removed.
Ratio SFAC
The nominal ratio scaling factor used for Stoichiometric Ratio Control in burn-
er fuel/air control applications. Adjustable from 0.010 to 99.999. – refer to the
Ratio Control section.
Ratio NO
A constant between 0.0 & 9999.0, added to the x1 (input 1) value in Stoichio-
metric Ratio Control mode to allow for atomizing air when calculating the pro-
cess value. The total air flow is therefore x1 + NO
Primary Cycle Time
The primary power cycle time. Adjustable from 0.5 to 512 seconds. Applied for
time proportioned primary relay, SSR driver or triac control outputs – Not used
for VMD Control modes.
Secondary Cycle Time
The secondary power cycle time when dual control is used. Adjustable from
0.5 to 512 seconds. Applied for time proportioned primary relay, SSR driver or
triac control outputs – Not used for VMD Control modes.
Summary of Contents for Chromalox 4081
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