Advanced Pf3100 Software Features - ProFire PF3100 Product Manual

17.8 ADVANCED PF3100 SOFTWARE FEATURES

17.8.1 PID CONTROL
Below is a brief overview of the PID control features available on the PF3100. Refer to
for additional details and configuration information. The following terms are used to describe the system behavior
in the various PID control modes:
• Primary Process Temperature: The main process temperature as specified in the Temperature Wizard Create
Inputs Tab.
Secondary PID Input: An auxiliary process temperature as specified in the Temperature Wizard Create Inputs
•
Tab or a Secondary PID Input as configured in the I/O Expansion Wizard Add Inputs Tab.
Temperature Control Valve (TCV): A device installed in the main fuel train that restricts gas flow proportionally
•
in accordance with a 4-20mA input from the BMS controller. This device must be wired to the BMS Aux output
terminals.
17.8.1.1 BASIC PID CONTROL
In basic PID control applications, the TCV is controlled in accordance with the configured BMS PID settings to
attempt to maintain the Primary Process Temperature at its configured Process Setpoint.
17.8.1.2 CASCADED PID CONTROL
In Cascaded PID control applications, the TCV is controlled and the Primary Process Setpoint is adjusted, both in
accordance with the configured BMS PID settings, Secondary PID settings, and Advanced PID settings to attempt to
maintain stability of a lagging Secondary PID Input at its configured Setpoint.
Example - Consider a line heater application where a stable outlet temperature is desired. The TCV directly controls
fuel flow to the main burners heating the Bath which in turn heats the Outlet process fluid.
In this example, the controller is free to change the Primary Process Setpoint between 380
accordance with the configured PID parameters, as required to attempt to maintain stability of the Outlet
temperature. With basic PID control on the Outlet only, the Outlet temperature is achieved at the expense of Bath
stability. With Cascaded PID control, the Outlet temperature can be achieved while maintaining Bath stability.
17.8.1.3 PID STAGING
PID Staging allows control based on either the Primary Process Temperature or the Secondary PID Input depending
on a specific trigger condition. The controller modulates the TCV based on the configured Primary Process PID
settings until the condition specified by the PID Staging Mode Setting is satisfied. At which point, the controller
modulates the TCV based on the configured Secondary PID settings.
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PID Input Name
Primary
Bath
Process
Secondary PID Outlet
PID Tuning Guide
Process Setpoint Setpoint
Setpoint Max setting Min setting
400°F 380°F 420°F
375°F N/A
PF3100 Product Manual
DOC-001149 v8.0
document
PID
Parameters
As required
per PID tuning
N/A
F and 420 F, in
° °
167