Retrofit SCR Aftertreatment Caterpillar

Aftertreatment Operation

Usage:

- ES7

Retrofit SCR Aftertreatment Operation

The Retrofit SCR Closed-loop Controller, once properly commissioned, is designed to operate without operator intervention. The system uses all sensor inputs to determine start-up, shut down, and the precise amount of DEF to deliver to the injection system. The controller software measures operating conditions and adjusts the amount of DEF injection to achieve the desired reductions.

Software Version 6.0.9

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Illustration 1	g03413265

The Operation tab displays the operation screen.

The following parameters are viewable in the operation screen:

Desired NO_x reduction (percent).
Actual NO_x reduction (percent).
Pump output of DEF (liters per hour).
Pre-SCR catalyst NO_x or engine out NO_x value (ppm).
Post-SCR catalyst NO_x or stack out NO_x value (ppm).
Boost pressure (psi).
Boost or intake manifold temperature (degree C).
Exhaust back pressure (inches of water).
Exhaust temperature (degree C).
Mode of operation.
Cumulative DEF.
Last cumulative DEF reset.
Engine hours (length of time since commissioning that the system has sensed a boost pressure).
E-POD hours (length of time pump is operation).

In the Operation tab the user can monitor operating parameters and change the desired amount of NO_x reduction.

Perform the following steps to change the value of a variable:

Touch the white box with a stylus or select the white box with a mouse.

Enter the desired value in the appropriate white box by touching numbers with a stylus or using keyboard numeric keys.

To accept the value, click anywhere outside the white box. The value will not be accepted if the Enter key is used on a laptop or USB keyboard.

Verify that the value in the gray box has changed as this value is the value the controller uses.

Touch the "Save" key if you want the desired value to be permanent in the program.

Modes of Operation

Standby - The green LED lamp is the only lamp on. No air or DEF is flowing and the system has purged. Standby is the default mode and the mode the system will return to anytime an operational condition is not met.

Startup - Start-up mode is used any time the system switches from standby to normal operation. The system will purge both lines with air. Startup mode will initiate the pump to fill the DEF line for NO_x reduction to begin. The blue LED lamp will turn on once DEF starts to flow.

Run - The system will enter the run mode once the startup mode exits. The run mode is indicated by an illuminated solid blue LED lamp. In run mode, the DEF is being dosed to the reactor according to the amount of NO_x in the exhaust. The pump speed will vary accordingly.

Purge - The system switches out of normal operation and enters a purge mode to prevent DEF from crystallizing in the lines. Purge mode is indicated by a flashing blue LED lamp and pump speed indicating zero. Pressurized air is flowing through both the DEF and air lines. The purge cycle lasts 6 minutes.

Fault - If the system is experiencing a low air line pressure for more than 8 hours continuous. The system goes into a fault mode to alert the operator. The green LED lamp is on and the red LED lamp is flashing.

Manual Purge - A manual purge switch is provided on the DIN rail to allow the user to exit normal operation. Once the switch is triggered, the red LED will begin to flash and the system will enter a purge mode (flashing blue LED). Once the purge is complete, the system will enter startup mode and continue to run. If the conditions are not met when the switch is returned, the system will remain in standby until the conditions are met. The flashing red LED will turn off.

Note: Ensure that the switch is returned to the Off position after the purge cycle has been triggered.

Normal operation will be disabled until the manual purge cycle switch is returned to the center position.

Operation

Air and DEF

Turn on the ball valves for air and DEF flow.

Set air pressure to 482.6 kPa (70 psi) using the key on the regulator. The regulator is located on the lower left and inside the dosing cabinet. To increase air pressure, turn the key clockwise. DEF should be visible in the clear sediment filter located on the DEF line.

Status

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Illustration 2	g03413239

The Status Tab displays the status log file. Any changes to the status of the system will be recorded on this tab. The systems status is also shown on the Operations Tab in the status box. Possible text displays, with an explanation of each, follows:

No problems found - System is operating.
Air line pressure too low - The air solenoid is open, but the line pressure is not high enough to open the pressure switch. A warning is displayed.
Back-pressure too high - The exhaust back-pressure is higher than the software imposed limit. A warning is displayed.
Exhaust temperature too low - The exhaust temperature is lower than the software imposed limit. A warning is displayed and the system enters Purge mode followed by Standby.
Boost pressure too low - The boost pressure is lower than the software imposed limit. A warning is displayed.
Air line fault. Reboot to continue - The air line pressure into the dosing cabinet has been too low to start the system for the past 8 hours. A controller reboot is required to reset this fault.
Hardware Purge - The DIN rail mounted purge switch is in the "ON" position.
Exhaust Pressure Sensor Fault: Check Connections – The controller is not receiving a signal from the exhaust pressure transducer. Check the wiring and transducer for problems.
Boost Pressure Sensor Fault: Check Connections – The controller is not receiving a signal from the boost pressure transducer. Check the wiring and transducer for problems.

If the NO_x sensors are not communicating, the system defaults to an Open loop condition. These codes continue until the NO_x sensor error is corrected. During OL Mode, system will display 85 percent reductions which are default values and actual reductions will be unknown.

Software Version 10.1.10

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Illustration 3	g03655343

The "Operation " page web address is http://169.254.02/caterpillar/web/operation.htm. The "Operation " page can be viewed on the touch screen and the user can monitor operating parameters. The following parameters can be viewed:

System Name (location and site specific)
Cabinet Serial Number
SCR System Serial Number
Engine Serial Number
Status (current state of the SCR system)
Current mode
Dosing hours
Controller Temperature
Boost Pressure
Boost Temperature
Exhaust backpressure
Exhaust alarm limit
Exhaust temperature
Heater temperature
Exhaust inlet temperature
Exhaust outlet temperature
Pump output of DPF
Cumulative DEF
Heater Output (if equipped)
Software version
Status window

Modes of Operation

Standby - The green LED lamp is the only lamp on. No air or DEF is flowing and the system has purged. Standby is the default mode. The system will return to Standby anytime an operational condition is not met. Refer to the Status section for more information.

Sensor Check - The SCR controller checks air pressure status and initiates NO_x sensor warm-up, this takes 3 minutes.

Tube Fill - "Tube Fill" is used any time the system switches from standby to normal operation. This mode fills the DEF line until NO_x reduction begins. The blue LED will flash once DEF starts to flow.

Run - Once "Tube Fill" is completed, "Run" mode will begin. "Run" mode is indicated by a solid blue LED. "Run" mode is the normal operating condition of the system. DEF is being dosed to the injector assembly according to the amount of NO_x in the exhaust, boost pressure sensed, and the dosing map flow rate. The pump flow rate will vary accordingly to the engine load.

Dry Out - A presence of DEF has been sensed at system startup. A greater than 15 percent emissions reduction is sensed before dosing has begun. Dosing will not begin until the residual DEF can be burned from the reactor. This enhances the performance of the system once dosing begins.

Slip - Excess DEF has been sensed within the SCR system. Dosing has been temporarily suspended until system dry out is achieved.

Rate Reduction Mode (RRM) - Successive slip events have triggered a Rate Reduction Mode and the system is operating at a lower reduction target than specified at system set-up.

Note: Ensure that the switch is returned to the Off position after the purge cycle has been triggered.

Normal operation will be disabled until the manual purge cycle switch is returned to the center position.

Status

The "Status" window displays the system status. Messages and Errors are displayed within this text box while they are current. A history of the status display messages can be obtained by a Local Cat^® Dealer.

Possible messages and errors:

Error 0: Air Line Pressure too low - The air pressure switch registers less than 276 kPa (40 psi). A warning is displayed and the system enters "Purge" mode.
Message 1: Exhaust Temperature too low to dose
Message 2: Boost Pressure too low to dose
Message 3: Air Line fault - The air line pressure into the dosing cabinet has been too low to start the system for the past 8 hours. A controller reboot is required to reset this fault
Message 4: Manual purge switch activated
Error 5: Currently running Open Loop mode - No connection to Pre NO_x sensor
Error 6: Currently running Open Loop mode - Pre NO_x sensor not at temperature
Error 7: Currently running Open Loop mode - Pre NO_x sensor signal not valid
Error 8: Currently running Open Loop mode - No connection to post NO_x sensor
Error 9: Currently running Open Loop mode - Post NO_x sensor not at temperature
Error 10: Currently running Open Loop mode - Post NO_x sensor signal not valid
Warning 11: Back Pressure too High
Error 12: Exhaust Thermocouple Fault - Check Connections
Error 13: Boost Thermocouple Fault - Check Connections
Error 14: Exhaust Pressure Sensor Fault - Check Connections
Error 15: Boost Pressure Sensor Fault - Check Connections
Error 16: Five Volt Supply Fault - The voltage is outside the fault set points
Error 17: Twelve Volt Supply Fault - The voltage is outside the fault set points
Error 18: Heater Temperature too High - The heater temperature is above the fault set point
Error 19: Chassis Controller Temperature too High - The chassis temperature is above the fault set point
Message 20: System is in Slip - The system is experiencing a slip condition. The dosing will be reduced until the condition is corrected and normal operation will begin again
Message 21: RRM enabled - (Reduced Reduction Mode) The system has experienced a slip condition and could not be corrected after three attempts. The system will attempt lower percentages of reduction until a stable reduction is reached

Operation

Powering Up the Dosing Cabinet

Turn on both breakers located inside the dosing cabinet. There will be a 5 to 10 second delay following power-up until a green LED on the outside cabinet door illuminates. A red/green LED on the dosing pump should illuminate. The LED indicates the unit has power. Operating in the proper "ANALOG" mode, the pump displays a steady green light. Turn on the Touch Screen Panel. The control program should automatically boot up on the Touch Panel screen.

Air and DEF

Turn on the ball valves for air and DEF flow.

Set air pressure to 482.6 kPa (70 psi) using the key on the regulator. The regulator is located on the lower left and inside the dosing cabinet. To increase air pressure, turn the key clockwise. DEF should be visible in the clear sediment filter located on the DEF line.