WHEEL-COMPRESSOR 7N7749 - Caterpillar

Caterpillar Monitoring System
The engine is equipped with a programmable Caterpillar Monitoring System. The Electronic Control Module (ECM) monitors the operating parameters of the engine. The ECM can initiate responses if a specific engine parameter exceeds an acceptable range. Three possible responses may be available for each parameter: "", "DERATE" and "SHUTDOWN". Some of the responses are not available for some of the parameters. An ET service tool is used to perform the following activities:
Select the available responses.
Program the level for monitoring.
Program delay times for each response.The default settings for the parameters are programmed at the factory. To accommodate unique applications and sites, the parameters may be reprogrammed with an ET service tool.The screens of the ET service tool provide guidance for the programming. The following options can be programmed "ON" or "OFF": , "", "DERATE" and "SHUTDOWN".The screens of the ET service tool also provide guidance for changing setpoints. For information on programming the Caterpillar Monitoring System, use the appropriate ET service tool and see the Service Manual, "Troubleshooting" module.The Caterpillar Monitoring System is enabled after the engine is started. When the engine rpm exceeds 50 rpm below low idle, the ECM begins checking parameters. The ECM monitors the parameters in order to determine if the parameters exceed the setpoints.If the monitoring system initiates a warning, a deration, or a shutdown, the event is logged into the ECM. This occurs even if the parameter is programmed "OFF". If a setpoint for a parameter is exceeded, the event will be logged.Any failure of a sensor will result in disabling the corresponding portion of the monitoring system. The failure of a sensor will cause an "ACTIVE" diagnostic code for the sensor.The derating is cumulative. For example, a derating of five percent followed by a derating of two percent results in a total derating of seven percent. If the conditions that cause the derating are not corrected, the derating will continue.Default Settings for the Caterpillar Monitoring System
Derate - This is a reduction of engine horsepower in response to an abnormal operating condition.Setpoint - This is a specific value which can activate the following responses: warning, deration and shutdown. The setpoint can be a pressure, a speed, a temperature, or a voltage.Hysteresis - This is the change in the signal from a sensor that is tolerated by the ECM. This is the difference between the setpoint that activates a response and the value that deactivates the response. For example, a warning for low voltage can activate if a value below 20 volts is detected by the ECM. The voltage must rise to 22 volts in order to clear the warning. The hysteresis is the 2 volts that are above the 20 volts.Voltage
The ECM automatically warns the operator of low system voltage. The default settings that are programmed at the factory are listed in Table 1.
Table 1
Voltage Monitoring
Parameter Default Setting
Warning setpoint 20 volts
Warning delay 10 seconds
Hysteresis 2 volts
Security level No required password If the voltage is below 20 volts for 10 seconds, a