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SLC4075 TouchScreen Gateway Installation & Operating Manual
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16
Steam Boilers or plants with high thermal inertia
Steam Boilers or plants with high thermal inertia
For a plant that has a high thermal inertia, such as a steam plant, the application of heat may be applied more
gently, while maintaining a high Proportional value and low Integral value, by increasing the “On Time Delay” of
the SLC4000 master. The delay is adjusted using RV1 in combination with SW2-2 through SW2-4 for a time
delay between steps, from 1 second to 8 minutes. For an SLC4000-1, this time delay is between the application of
the next 1/7th of the full output. The application of the amount of heat is delayed on an increasing demand, while
allowing the rapid removal of heat as the process variable approaches the setpoint. This maintains the benefit
using a high Proportional and low Integral values, resulting in a slower approach to the set point, but a rapid
removal of heat as the process variable approaches the setpoint, minimizing overshoot. The SLC4000 master has
an “Off Time Delay” set by SW2-5, which sets either a 2 or 5 second delay. Verify that this switch is set to ON
for a 2 second delay. This approach is preferable over using a lower P or using a higher I value, as it minimizes
“Integral windup”, which can occur on either plants with high thermal inertia or loads that can rapidly change.
SLC4060 RTD Sensors
a.
RTD1 and RTD 2
b.
Deg F
c.
Deg C
d.
ADC Cnts
e.
RTD Bias Cnts is used to adjust the displayed RTD displayed temperature to compensate for wiring resistance or
to calibrate the unit to the actual temperature.
A Warning Message “
RTD1 Open Ckt
” or “
RTD2 Open Ckt
” is displayed if the wires to the RTD is detected as
being open
OR
no RTD is installed. To remove this message when no RTD is used, add a jumper between:
For Unused RTD1:
Jumper TB1 and TB2
.
For Unused RTD2:
Jumper TB3 and TB4
.
SLC4060 Aux Sensors
a.
GPA1
b.
GPA1 in engineering units
c.
GPA1 Span%
d.
GPA1 Bias% is used to calibrate GPA1
e.
Input Cfg: either Full Span or 20% offset as set by the DIP switches on the PGW
f.
GPA2
g.
GPA2 in engineering units
h.
GPA2 Span%
i.
GPA1 Bias% is used to calibrate GPA2
j.
Input Cfg: either Full Span or 20% offset as set by the DIP switches on the PGW
