3516B Generator Set Engines with Dynamic Gas Blending Caterpillar

• The In Cylinder Pressure Sensor (ICPS) input

• The engine exhaust temperature input

• Fuel actuator valve position

Illustration 1	g06205789

The Electronic Modular Control Panel (EMCP) requires enablement of "Gas Blending Control" to begin blending gas. It is required to enable "Gas Blending Control" at the EMCP upon power cycle if gas blending operations are requested.

Gas Substitution Status

The Gas Substitution status parameter has three possible states, active, inactive, or locked inactive. These states are used to identify if the engine operating conditions to enable gas blending have been met.

7 Potential Reason Codes

• No reduction

• Abnormal cylinder pressure

• Diagnostic Trouble Code (DTC) active

• Low engine load

• High turbocharger inlet temperature

• High detonation level

• High fuel actuator valve command

No Reduction

The reason code, No Reduction, is displayed when the following items are within acceptable limits and operating properly:

• Load

• Speed

• Fuel quality

• Fuel supply

• Coolant temperature

• Intake manifold air temperature

• Atmospheric pressure

Factory testing has determined the maximum allowable substitution for specific speeds and loads with optimum fuel quality. The maximum allowable substitution is to ensure safe engine operation and compliance with the published emissions limits.

When this reason code is active, the substitution is at the expected percentage based on the speed and load the engine is running.

Abnormal Cylinder Pressure

The reason code, High Cylinder Pressure, will be displayed when the ICPS has detected cylinder pressures are higher than allowed. The gas substitution will remain active but at a reduced substitution percentage.

Diagnostic Trouble Code (DTC) Active

The reason code, DIAG ACTIVE (Diagnostic Trouble Code (DTC) Active), is present when there is an active engine diagnostic code. The active engine diagnostic code has caused the DGB control system to eliminate or reduce substitution.

When an active code on the engine is present, the focus should be resolving the active code. Refer to Table 1 for the list of active codes.

Low Engine Load

The reason code, LOW LOAD (Low Engine Load), is present when the engine load is less than the required minimum to allow substitution. The gas substitution will remain active but at a reduced substitution percentage.

Probable Causes:

Low load

• The engine is being operated below the minimum load range for gas substitution.

• For drilling generator packages, the load must be 15% or greater for gas substitution to be enabled.

Lost load signal

• Verify that the EMCP is generating a load signal.

• Verify that the ECM is receiving the load signal through Cat^® Electronic Technician (ET).

Incorrect load signal

• Check the load signal that is being generated on the EMCP with the load calculated by the customer controller.

High Turbocharger Inlet Temperature

The reason code, HI TURBO TEMP (High Turbocharger Inlet Temperature), is present when turbine inlet temperature exceeds the set value for the programmable monitoring system. The gas substitution will remain active but at a reduced substitution percentage.

Probable Causes:

• Turbine inlet temperature reads high

• Replace thermocouples if one is radically off from other

• Injector leakage

• High inlet manifold pressure

• High inlet manifold temperature

• Turbocharger performance issue

• Intake restriction

• Exhaust restriction

Refer to Troubleshooting, "Inlet Air Is Restricted".

Refer to Troubleshooting, "Exhaust Temperature Is High".

High Detonation Level

The reason code, HI DET LEVEL (High Detonation Level), is present when the ICPSs have measured cylinder pressures in the range that detonation occurs.

Probable Causes:

• Gas quality

• High inlet manifold pressure

• High inlet manifold temperature

• Incorrect timing calibration

• Faulty circuit for the ICPS sensor

• Intake restriction

• Turbocharger damage

• Excessively low inlet manifold temperature

• Valve lash

Refer to the Troubleshooting, "Detonation Occurrence".

High Fuel Valve Command

The ECM controls the fuel actuator valve to deliver gaseous fuel to the engine. The reason code, HI VALVE CMD (High Fuel Valve Command), is present when fuel actuator valve reaches 80% open. Essentially the engine needs more gaseous fuel than can deliver at the maximum fuel valve position. The gas substitution will remain active but at a reduced substitution percentage.

Probable Causes:

Low Supply Pressure

• The recommended supply pressure range is 207 kPa to 241 kPa (30 psig to 35 psig)

• The acceptable supply pressure range is 83 kPa to 689 kPa (12 psig to 100 psig)

The supply pressure can be lowered below the recommended 207 kPa to 241 kPa (30 psig to 35 psig) if the volume is sufficient to allow enough gas flow.

Gas Quality

• Low BTU heat value gaseous fuel

• High inert gas level

Refer to Application and Installation Guide, LEBW4977, "Gaseous Fuels".

Regulator Pressure

Adjust the regulator pressure to 10.3 kPa to 24.1 kPa (1.5 psig to 3.5 psig) supply to the fuel valve.

If adjusting the regulator pressure does not work, check the following:

• GSOV failure

• Pressure regulator failure

• Upstream restriction of supply gas

Incorrect Mixing Tubes

• There are two different Btu ranges for the mixing tubes. Verify that the correct range is being used on each engine.

Fuel Line Restriction Downstream of Fuel Valve

• Check for foreign objects in the fuel line

• Check for proper mixing tubes

Gas Supply Pressure Fluctuations

• Inadequate gaseous fuel supply or flow rate

Gas Substitution Status

Illustration 2	g06207238

The Gas Substitution Status parameter has three possible states, Active, Inactive, or Locked Inactive. These states are used to identify if engine operating conditions to enable gas blending have been met or have not been met.

When the Gas Substitution Status is Inactive, gas blending is not allowed. The following operating conditions will inhibit gas blending:

• High altitude operation

• Cold-Mode active

• High or low intake manifold air temperature

Once engine operating conditions have qualified for Active gas blending, the Gas Substitution Status will change from Inactive to Active.

Another Gas Substitution Status is Locked Inactive. This status is present when there is an active diagnostic code. Gas blending will not be allowed while the DTC is active and will not resume normal blending operations until the code is no longer active.

Gas Substitution Reason Status

The Gas Substitution Reason Status parameter provides information to the user to indicate if full gas blending capability is allowed or if the percentage of gas blending allowed has been reduced due to an engine or component operating condition. The abnormal conditions will allow for the Gas Substitution Status to remain Active and blending continues but at a reduced rate when compared to normal running conditions.

• No Reduction allows for full gas blending

Reduced gas blending is active when the following conditions are detected:

• Low engine load

• High fuel valve command

• Abnormal cylinder pressure

• High knock level

• High turbocharger inlet temperature

The High Fuel Valve Command is indicating that the fuel control valve has reached it maximum open position. There may be a problem with fuel pressure or fuel quality that is resulting in the valve being in the full open position. The fuel valve does not operate at a full open position when normal fueling is present.

Gas Blending Percentage and Load

Illustration 3	g06207240

Engine load must be at least 15% before gas blending is enabled. As engine load increases, the amount of allowed substitution also increases. After approximately 80% load, the need for diesel fuel increases and the amount of substitution is decreased.