AFRC Controlling the Engine
Detecting the Run Signal
With the engine running, the AFRC will detect the engine operation through the sensor trigger defined within the Run Signal Trigger setting (Main setup slide 4).
Sensor Warm Up
Upon detecting the system run signal, the bank status within the control box will display “Heater Warmup” indicating the sensors have been started. After the sensor heaters are warmed, the AFRC will be ready to control. When the AFRC is ready, and in “Manual” control mode, the bank status will display “Ready” and will wait until the control mode is transitioned from “Manual” to “Auto”. A security level of Setup or Engineering is required to toggle the control mode.
If the AFRC is already in “Auto” mode, it will start the process for initializing control.
Load Delay
Once the sensor is warm and in “Auto” mode, the AFRC will go into a load delay. By default, the load delay waits 30 seconds before the controller starts to move the valve.
If an AFRC Advanced is used and “Auto Control” is enabled, the controller not transition to delay mode until the pre-catalyst or post-catalyst thermocouple read a light off temperature of 550 degrees F.
Starting Control
When starting control, the bank status will update to “Attempting To Control”. The valve will automatically adjust to try and match the actual O2 reading with the desired target setpoint. As the valve finds the position that’s meets the target and is stable, the status will update to “Controlling”.
Optimizing The Target Setpoint
The oxygen target setpoint “Target” should be set to optimize catalyst performance. This should be conducted while the engine is at a normal operating temperature and under normal loading. An exhaust gas analyzer should be used to reach optimum performance.
If an AFRC Advanced is used and “Auto Control” is enabled, no target setpoint adjustment is necessary.
Stopping the Engine
The engine may be stopped at any time. The AFRC will detect the engine has stopped based on the trigger selected on the Run Signal Trigger setting. When using thermocouples as the run indicator, the controller will detect the engine has stopped after the pre-catalyst thermocouple drops below the trigger point (450°F by default). When using an oil pressure switch, AFRC RPM, or Ignition State, the controller will immediately detect the engine has been shut down.
After the controller detects a shutdown, the digital power valve will fully open and then move to the startup home position. This digital power valve cycle is repeated once after each engine shutdown to maintain calibration of the digital power valve position.
