3938
For Process Control, the Proc Temp signal is the one compared to the Pilot Off, Low Fire,
Process, and Deadband setpoints.
High Temp ESD Setpoint (Menu 5)
This setting is used to protect the burner and other equipment from overheating. If either
the High Temp or Process thermocouple readings exceed this setpoint, the burner will
immediately shut down. This setting can be set to a maximum of 1350˚C. The minimum value
is 1˚C higher than the setpoint below it. Depending on which settings are enabled, this will
be the Pilot Off, Low Fire, or Process Setpoint.
Pilot Off Setpoint (Menu 1)
If the Process Temperature goes above this setting, the Pilot Valve will close and the system
state will change to “Waiting on Temp”. This is often done to conserve pilot gas when it is not
needed. This setting is hidden if Pilot Off in menu 5 is set to Disabled. This setting can be set
to a maximum of 1˚C below the High Temp ESD Setpoint. The minimum value is the same as
the setpoint below it. Depending on which settings are enabled, this will be the Low Fire or
Process Setpoint.
Low Fire Setpoint (Menu 1)
If the Process Temperature goes above this setting, the Low Fire Valve will close and the
system state will change to “Pilot On”. This setting is hidden if Low Fire in menu 5 is set to
Disabled. This setting can be set to a maximum of 1˚C below the High Temp ESD Setpoint or
the Pilot Off Setpoint if it is enabled. The minimum value is 1˚C above the Process Setpoint.
Process Setpoint (Menu 1)
If the Process Temperature goes above this setting, the Main Valve will close and the system
state will change to “Low Fire”. This setting can be set to a maximum of 1˚C below the High
Temp ESD Setpoint, the Pilot Off Setpoint if enabled, or 1˚C below the Low Fire Setpoint if
enabled. The minimum value is the Low Temp Alarm or Deadband (whichever is larger).
Low Temp Alarm Setpoint (Menu 1)
If the Process Temperature goes below this setting, the Low Temp Alarm will be asserted and
the status contact will open. This setting can be set to a maximum of the Process Setpoint
value. The minimum value is 1˚C. Set to 0˚C to disable the Low Temp Alarm.
Deadband (Menu 1)
The Deadband setting provides a temperature margin below the Process Setpoint. For the
main valve to open, the temperature must be below Process Setpoint minus the Deadband
setting.
The Deadband setting also provides a temperature margin below the Low Fire Setpoint when
the Low Fire Enable setting is set to “On At Low Fire Setpoint”. In this case, the Low Fire
valve will open when the Process Temperature is below the Low Fire Setpoint minus the
Deadband setting and will close when it is above the Low Fire Setpoint.
The Deadband setting also provides a temperature margin below the Aux Setpoint when the
Aux Temp Mode setting is set to “Temp Main Ctl”. In this case, the main valve(s) will open
when the Auxuliary Temperature is below the Aux Setpoint minus the Deadband setting and
will close when it is above the Aux Setpoint.
This setting can be set to a maximum of 150˚C or the Process Setpoint, whichever is lower.
The minimum value is 1˚C.
AUX Setpoint (Menu 1)
This setpoint is enabled only if Aux Temp Mode in menu 5 is set to “Temp Main Ctl” or
“Temp ESD”. In the first case, if the Auxiliary Temperature goes above the Aux Setpoint, the
main valve(s) will close. The pilot will remain on until the Process Temp exceeds the Pilot
Off Setpoint (if Pilot Off is enabled). In the second case, the system will shut down if the
Auxiliary Temperature goes above the Aux Setpoint. This setting can be set to a maximum of
1350˚C. The minimum value is 0˚C.
3.5 | Optional Settings
4-20MA OUTPUT SETTINGS
The 4-20mA Output is built into the Terminal Card (not part of the 4-20mA Expansion Card). It can be used
to echo the process temperature to a PLC or control a proportional valve.
4-20 Output Mode (Menu 5)
Set the 4-20mA Output mode to Process Temperature, Valve Control 1, or Valve Control 2.
The 4-20mA Output is intended to drive a proportional valve. The signal is scaled such that
4mA = Valve Closed and 20mA = Valve Fully Open. A PID control loop based on Process
Temperature feedback is used to determine how much the valve should be open at any given
point in time. More details can be found in the PID Controller section.
The Valve Controls use a traditional safety solenoid valve connected to the PF2100’s Low Fire
outputs. The Low Fire setting must also be enabled by setting it to “On at Proc Setpoint.”
1. Process Temperature
In this mode, the 4-20mA Output will encode the Proc
Temp signal as a 4-20mA signal. Note that the Proc Temp
may correspond to either the Process Thermocouple or the
AUX Thermocouple input depending on the Process Control
setting. The signal is scaled such that 4mA = 0C and 20mA =
the High Temp ESD Setpoint.
2. Valve Control 1
When the PF2100 enters Low Fire, the proportional valve
begins fully closed and linearly ramps so that it reaches the
4-20 Low Fire setting just as the Low to High Fire Delay
elapses. Once High Fire begins, the PID Controller adjusts the
valve accordingly.
3. Valve Control 2
When the PF2100 starts, the proportional valve idles at
the 4-20 Low Fire setting. Once High Fire begins, the PID
Controller adjusts the valve accordingly.
4-20 Low Fire Setting (Menu 5)
This setting is only available when the 4-20 Output Mode is set to Valve Control 1 or Valve
Control 2. It specifies the minimum value that the proportional valve will ever be open. This
is the starting position of the main valve each time it is turned on. It can be set to any value
from 0% to 70%.
ALARM / STATUS CONTACT SETTINGS
The Status Contact will always open if the system is shut down due to an alarm condition. There are two
settings that affect the behavior of the Status Contact: Alarm Mode and Low Temp Alarm Setpoint.
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