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SCR system protection
The machine control system detects and warns about improper or even dangerous functioning conditions of the
SCR system:
1. The level of DEF/AdBlue® in the tank lowers until the tank is completely empty.
2. The quality of DEF/AdBlue® in the tank does not conform to the required specification, or a fluid different than
DEF/AdBlue® is filled into the DEF/AdBlue® tank.
3. One or more components of the SCR system have a failure.
These conditions shall be promptly addressed in order not to severely damage the SCR system. Therefore, as one
of these conditions comes up, the machine control system displays a specific warning sequence in order to induce
the operator to take proper actions.
The inducement sequence has four steps:
A. The SCR system is functioning in proper condition.
B. The SCR system is getting to an improper or dangerous functioning condition, and a warning to the operator is
thus given.
C. The SCR system is at risk of damages, and an early inducement is thus given to the operator for stopping operation
as soon as possible, and taking proper actions.
D. The SCR system is at risk of serious damages, and a final inducement is thus given to the operator for stopping
operation immediately, and taking definitive actions.
From the step B to the step D , the machine functionalities are further limited:
B. The engine is at rated output.
C. The engine is limited to 70% of the rated output. A derate icon is displayed.
The engine is derated.
D. The engine is limited to 60% of the rated output, and the engine speed is limited to low idle. A no power warning
is displayed
The engine has no power.
In the step D of the inducement sequence, the machine has a minimal operating capacity. This minimal operating
capacity is intended to reach a safe condition: as a safe condition is reached, stop the engine, and make sure to take
the appropriate action required by the inducement sequence, as for example refilling DEF/AdBlue® or repairing the
SCR system.
NOTICE: The recommended practice is to stop operation and take proper actions at the step B of the inducement
sequence, in order to avoid severe damages to the SCR system and to the other main systems of the machine.
3 - CONTROLS AND INSTRUMENTS
3-89
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