While in Engineering security mode, the Engineering Setup screen (Lite Pg. 304, Adv. Pg. 207) is available through the Setup screen (Lite Pg. 301, Adv. Pg. 201). This screen provides access to gain adjustment and other engine configuration settings.
AFRC Engineering Setup Screen
The AFRC operates on a PID control loop to automatically adjust the valve to match the actual sensor reading to the target setpoint. By default, the control loop has been pre-tuned to find the target setpoint quickly while maintaining stability. If the condition exists where the valve needs to be either more or less responsive, the PID control loop can be adjusted by selecting the “Faster” or “Slower” buttons around the “Response Time” label. Slowing the valve response will decrease the sensitivity of the control loop, and increasing the valve response will increase the sensitivity of the control loop. The individual PID values are automatically adjusted based on the single “Response Time” value. The default “Response Time” value is 50 and is adjustable between 0 and 100.
The AFRC Advanced has the ability to switch between control types “Setpoint” and “Auto Control”. The AFRC Lite is fixed for “Setpoint” type control.
“Auto Control” is a patented control algorithm that uses both a pre-catalyst and post-catalyst O2 sensor to find the most appropriate target setpoint and maintains that setpoint through a variety of conditions. The target setpoint is not user adjustable and is managed by the AFRC Advanced without the need for any user input. “Auto Control” is only available for single bank and dual bank rich burn engine configurations. Multi-setpoint mapping is disabled while in this mode.
If “Auto Control” is selected as the control type, options will be made available to adjust the software to target either for a richer or leaner setting using the “Lean” and “Rich” buttons on the Engineering Setup screen (Pg. 207). By default, this setting is configured for equal CO and NOx reduction with a rich/lean setting value of 50. Due to varying site conditions, including fuel gas and ignition timing, this value may require an initial adjustment after installation. If lower CO emissions are desired at the expense of higher NOx, the rich/lean setting can be reduced by selecting the “Lean” button to adjust rich/lean value less than 50. Similarly, if lower NOx emissions are desired at the expense of higher CO, the rich/lean setting can be increased by selecting the “Rich” button to adjust rich/lean value greater than 50. The rich/lean value’s range is 0 to 100, where 0 is the maximum lean value and 100 is the maximum rich value.
When “Auto Control” is selected, an alarm is
automatically generated on the Alarm
Setup screen (Pg. 206) to switch to “Setpoint” control if the “Auto
Control” setpoint drifts below 600 or above 800. If the alarm is triggered,
it must be reset on the Alarms
screen (Pg. 40) before “Auto Control” can be re-enabled. Typical cause of the drift outside of this range is an
expired or ineffective Post-Cat O2 sensor.
“Setpoint” control mode controls off of a user, or mapping table, defined setpoint that corresponds with the desired emissions reduction. If desired, multiple setpoints can be used to automatically change the target setpoint based on sensor readings through the AFRC’s mapping feature.
The load delay setting adjusts the amount of time to delay the AFRC from taking control of the valve after it has detected a valid run signal and the sensors are warm. The intention of this configuration is to allow the engine to fully warm up and load before taking control.
The default value is set to 30 seconds, but the delay can optionally be configured to 1 minute, 5 minutes, 10 minutes, or 20 minutes.
The AFRC can be configured to control either a rich-burn or lean-burn engine. Adjusting this parameter sets various displays elements within the user interface.
The AFRC allows the O2 sensor type to be selected while the combustion type is configured as “Rich Burn”. The two O2 sensor types supported are narrowband and wideband. The narrowband sensor is a 4-wire heated sensor that can only read within a very narrow window around stoichiometric combustion and is suitable for rich burn combustion. The wideband sensor is a 6-wire that can read a much wider range and is suitable for both rich and lean burn combustion types.
NUMBER OF BANKS
The AFRC Advanced allows for the number of banks to be selected as one (1) or two (2). The AFRC Lite does not include this configuration as it is intended for single bank configurations only.