Fuel System (Air/Fuel Ratio Control)
The fuel system includes these components:
- Catalyst thermocouple sensor
- Engine control module (ECM)
- Fuel actuator and valve
- Inlet manifold pressure sensor
- Oxygen sensor and buffers
- Throttle actuator
- Throttle body
- Dual fuel system capabilities
The fuel metering valve controls the flow of fuel to the engine. The ECM determines the requirement for the mixture of air and fuel. The ECM sends a signal to the fuel metering valve. The fuel metering valve controls the volume of the gas flow to the engine.
The oxygen sensor measures the oxygen content in the exhaust gas. The inlet manifold pressure and engine speed are monitored. This information is provided to the ECM. The ECM uses this information to adjust the flow of fuel in order to meet emissions requirements. This adjustment is a continuous process during engine operation.
The fuel flows through the fuel metering valve into the carburetor. Air flows into the carburetor and is mixed with fuel. The air/fuel mixture enters the cylinders through a throttle valve. On turbocharged engines (if equipped), air is compressed and flows into the carburetor, where the air is mixed with fuel. The air/fuel mixture flows through the throttle valve and is cooled using the aftercooler before entering the cylinder.
The ECM sends a signal to the throttle valve. The throttle controls the flow of the air/fuel mixture to the cylinders.
Ignition System
The engine is equipped with an A4-E2 ignition system. The system is controlled by the ECM, and provides dependable firing and low maintenance. The system provides precise control of the spark and the ignition timing for each cylinder. The system also provides diagnostic capability that enhances troubleshooting.
The ignition system has four basic components: an air fuel ratio control system (AFRC) controlled by the electronic control module (ECM), an ignition transformer for each cylinder, wiring harness and spark plugs.
Lubrication System
The engine lubrication oil is circulated by a gear-driven pump. The oil is cooled and the oil is filtered. However, bypass valves provide an unrestricted flow of lubrication oil to the engine if the following conditions occur:
- The viscosity of the oil is high because the oil is cold.
- The oil cooler becomes plugged.
- The oil filter becomes plugged.
Cooling System
The jacket water coolant is circulated by a gear-driven centrifugal pump. A 90 °C (194 °F) temperature regulator regulates the temperature of the coolant. Heat can be removed from the coolant by a radiator or a heat exchanger.
For engines with a Separate Circuit Aftercooler (SCAC), the air is cooled by a heat exchanger. The water that cools the air in the heat exchanger is in a circuit that is separate from the jacket water. The aftercooler coolant is pumped by an auxiliary water pump. The SCAC is required to operate at one of the following temperatures. The engine rating depends on the temperature and the application.
- 32 °C (90 °F)
- 54 °C (129 °F)
For engines with air-to-air aftercooling, the aftercooler is supplied by the customer. This aftercooler is similar to a radiator. The inlet air is cooled by a fan that moves the ambient air through the radiator.
Engine Service Life
Engine efficiency and maximum utilization of engine performance depend on adherence to proper operation and maintenance recommendations. These recommendations include the use of certain lubricants, fuels, and coolants.
For the engine maintenance that is required, refer to the Operation and Maintenance Manual, "Maintenance Interval Schedule" (Maintenance Section).
Automatic Dual Fuel System Setup and Capabilities
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| Illustration 1 | g03605476 |
(1) Point A (2) Balance lines kept separate (3) Natural gas emission Adjustment screw (4) Balance line 1/2 inch diameter (5) Propane gas emission adjustment screw (6) Propane gas regulator (7) Solenoid valve (8) Vaporized propane gas (High BTU gas) (9) 1.5-3.0 in H2O negative differential from here to Point A (10) 5.5 inch ± 5 inch H2O differential here to Point A (11) Check valve (12) Manual shutoff valve or solenoid valve and pressure switch (13) Natural gas (Low BTU gas) (14) Pressure switch (15) Natural gas regulator (16) Fuel actuator (17) Carburetor | |
Note: Callouts (7), (8), (12), (13), and (14) are part of the OEM system.
The engine is shipped with a dual gaseous fuel arrangement (Natural gas/Field gas + Propane fuel train). The arrangement has two separate pressure regulators and fuel systems as shown in Illustration 1. This dual fuel system is only suitable with propane as the secondary fuel. No other fuel is acceptable for use with the secondary fuel train.
A propane gas emission adjustment screw (5) is placed in between the propane gas regulator (6) and the carburetor (17). The propane gas emission adjustment screw is used to adjust the Air/Fuel ratio for the propane.
ReferenceRefer to Special Instructions, REHS9280, "Air/Fuel Ratio Setup for Certified G3306B Generator Set Engines" for the Air/Fuel ratio setup instructions.
Note: The shipped factory engine configuration cannot switch between the different fuels automatically. As shipped, the engine must be shut down and the fuels switched manually.
The following guidelines are for automatic switching between the primary (natural gas/field gas) and secondary (propane) fuels. The engine software is programmed to allow for an automatic switch in ignition timing based. The customer can set up a system that allows for automatic switching between fuels using OEM parts similar to the parts listed in Illustration 1. The engine software allows for an automatic switch in ignition timing based on the output of the pressure switch (14). The pressure switch is located upstream of the natural gas solenoid. The pressure switch is customer provided and the specifications are available in Special Instructions, REHS9280, "Air/Fuel Ratio Setup for Certified G3306B Generator Set Engines". Before automatic switching of the fuel is permitted, complete "Part C" of Special Instructions, REHS9280 to ensure emissions compliance. Failure to do so will lead to higher emissions and could make the engine out of compliance.
In this system, the primary fuel has a lower British Thermal Unit (BTU) than the secondary fuel. Dual regulator systems can transfer between the two different fuel supplies while under load. Do not move the fuel regulators from the factory mounting positions. Any increase in the fuel line length can cause problems with the transfer between the primary and secondary fuel. The solenoid operated shutoff valves should be energized to run and be mounted as close to the regulators as possible. During normal operation using the primary fuel, both solenoid valves should be engaged. The primary fuel supplied by the low BTU regulator has greater pressure than the secondary fuel pressure. Any time the primary fuel is present, the propane gas regulator will stop the propane supply even though the solenoid valve is energized.
When the primary fuel supply pressure runs low, the deactivation of the pressure switch will change the engine timing to the secondary fuel supply. There must be a customer supplied system to de-energize the primary solenoid valve in order for the switch to take place. As fuel is used between the natural gas regulator (15) and the carburetor, the pressure in the supply line will drop. The propane gas regulator reacts to this drop and opens the supply of propane to the carburetor. Once the primary fuel pressure increases beyond that activation pressure, the pressure switch will close. Once closed, the change back to the primary timing and the low BTU solenoid should be programmed to energized.
Note: The secondary fuel (propane) solenoid is not supplied with the factory setup. The solenoid is customer supplied.
Note: For generator set engines, temporarily override the reverse power relay during changeover of fuel supplies. The time delays for solenoid valves will need to be determined at the site for changeover.
Generator Description
The SR4B brushless generator can be used with the following loads :
- Mixed loads of motors and lights
- SCR-controlled equipment
- Computer centers
- Installation of communications
- Petroleum drilling applications
The generator set packages can be utilized for prime power generation or standby power generation
SR4B generators are utilized in three-phase full-wave excitation and regulation. The generators are either four or six pole designs with six lead configurations or twelve lead configurations depending on frame size. The generators can produce electrical power in either 50 Hz or 60 Hz applications.
Solar Battery Charging System
Note: The section that follows only applies to the XG135 Generator Set.
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| Illustration 2 | g02704819 |
(1) Solar array panel | |
Solar Array Panel - One solar array panel is located on the roof of the power module (1) .
Check wire connections for tightness and corrosion, and exposed areas for chaffing and wear on a regular basis. Module surface may be cleaned as needed using a soap and water. Abrasive chemicals cannot be used in the cleaning of your solar module. The combination of water and electricity produces a shock hazard, disconnect your solar panel from the charge controller or battery prior to any cleaning process. Always wear protective rubber gloves and rubber sole shoes when working with electricity.
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| Illustration 3 | g02704821 |
Controller - The solar battery charging controller is located inside the upper generator terminal box.
During normal operation, the "Charging" LED should always be ON solid during sunlight to indicate the solar array is contributing power to the controller. The "Battery Status" green LED (one on the left) should either be ON solid (indicating batteries fully charged). Or the charging LED should be blinking (solar is charging) and the other two "Battery Status" LEDs (yellow and red) should remain off.
Battery type selection for XQ product is number 2 (Sealed). Temperature sensor for batteries is not used on XQ product.
Battery Connection - Battery "+/-" has an uninterrupted connection to the batteries. A two-pin connector is located near the batteries to allow isolation from the solar charging system if desired. If the connector is unplugged, the red "Battery Status" LED will be "ON" solid.
Switchable Ratings
Note: The section that follows only applies to the XG135 Generator Set.
Definition - The EMCP and CDVR voltage regulator each have three preprogrammed settings groups for up to four different voltage and machine ratings. A combination of two switch inputs to the EMCP will cause one of four settings groups to become "Active" for a desired voltage and frequency rating. The engine must be stopped for the switch inputs to effect a change in settings group activation. The EMCP will then send the "active group number" to the CDVR via the "CAN" communication port. The CDVR reads the "Active Group Number" sent from the EMCP and then activates the corresponding settings group within the CDVR. This activation eliminates field programming to change parameters, in multiple controls, in order to changeover the unit from one machine rating to the next. Benefits include:
- Quicker setup time to meet site requirements
- Reliable changeover method (all necessary settings changed over correctly every time)
- Anyone can perform changeover
Operator Control – The two switch inputs to the EMCP come from a linkboard position switch and a two-position voltage/frequency selector switch (VFSS). These components are located inside the upper terminal box. The linkboard is placed in the desired position and then the operator uses the VFSS to select the desired rating. This selection allows for two different rating selections with the linkboard in the Low Voltage position. This selection also allows for two different rating selections with the linkboard in the High Voltage position. Once the selection has been made, the engine ECM, CDVR, and EMCP 4.4 are configured automatically to the new setting. The unit is ready to run. The only control not affected is the UMR. The UMR, if installed, has settings which do not automatically change over. These settings are based on nominal 480V, 60Hz. These settings will not cause a shutdown at the lower voltages, however, unless running in a utility paralleling mode.
Verification – To view the active rating selection in the EMCP before startup, press the "AC overview" button on the EMCP. Then scroll all the way down in order to view which ratings have been selected.