Usage:
Configuration
The valve can be configured to accept a flow demand from the analog input, the PWM input, or the CAN port. The configuration also included user adjustable warning limits, and default values for failed sensor backup modes. The configuration can be viewed or changed online using the TecJet Service Tool. See Chapter 5 for information on installing the service tool.
Power-On Procedure
When power is applied to the valve, it performs a diagnostic check. If there are no problems detected, the actuator is enabled with 1.36 N·m (1.0 lb-ft) of torque, and the valve closes. If the flow demand source is configured for CAN, the valve reads the CAN ID input pins and begins sending diagnostic information on the CAN link. If a problem is detected, the valve will not operate and the status output will indicate a fault.
Typically the TecJet 52 is continuously connected to the supply voltage. If the flow demand source is configured to Jenbacher CAN, the keyswitch has no effect. If the flow demand source is configured for anything else, the keyswitch input must be connected to a high signal (supply [+]) for the valve to operate. When the keyswitch is off, the valve closes, if possible, and the actuator driver that positions the valve is disabled to minimize the amount of current drawn from the battery.
Normal Operation
If a valid flow demand and delta-pressure are present, the valve begins normal operation. The TecJet 52 calculates the area needed to provide the requested flow. This area is calculated using the delta pressure (inlet to outlet pressure differential), the absolute inlet fuel gas pressure, the fuel gas temperature, the fuel gas ratio of specific heats (K), the fuel gas density, and the calibration information stored in the valve. The actuator positions the valve to achieve the calculated area requirement.
Diagnostics
The valve continuously performs a variety of diagnostic checks. Diagnostic events are classified as warnings, errors or status indications. The status output indicates the overall status of the valve. A brief summary:
Warnings:
A warning indicates a condition that may require operator attention or intervention. For example, the valve may be operating in conditions that are outside its specification range, or a failure has occurred for which there is a back-up mode of operation, possibly with reduced accuracy or performance. If any warnings are active, the status output turns "off".
Errors:
An error indicates a problem that prevents the valve from operating, The valve closes, if possible, and remains inoperable until power is cycled. If the error persists, the valve requires service. If any errors are active, the status output turns "off".
Status Indications:
The valve provides the following status indications:
- * Zero flow detected-The flow demand is not present or is not valid. The valve is closed and the status output turns "off".
- * Zero pressure detected-The pressure across the valve is essentially zero, so no flow can occur. The valve is closed and the status output turns "off".
- * Flow not reached-The valve cannot achieve the demanded flow given the present operating conditions (fuel gas temperature and pressure, delta pressure, gas K and density). The status output turns "off".
- * Overall status OK-There are no errors or warnings, and the Flow not detected, Zero flow detected, and Flow not reached status indications are not true. The status output turns "on".
- * Zero pressure detected-The pressure across the valve is essentially zero, so no flow can occur. The valve is closed and the status output turns "off".
See Chapter 6 (Troubleshooting) for more information on abnormal operation.
Runs Hours Counter
The valve maintains a running hours counter that can be viewed or reset with the service tool. Running hours do not accumulate when the "Flow not detected" status indication is true.
Position Limiter
After the TecJet 52 is powered up and receives a flow demand, the valve remains closed until the delta-p sensor detects a non-zero valve delta-p. This non-zero delta-p is established when the fuel source is turned on. After sensing a non-zero valve delta-p, the valve is positioned according to an interpolated value from the position limiter table. This table contains three position vs. flow demand points. By limiting the valve position until fuel pressure is established, the delta-p required for the TecJet 52 to begin metering fuel is obtained at a lower fuel flow rate. This function ensures that adequate delta-p will be created, even with a substantially drooping fuel source, before allowing the TecJet 52 to begin metering fuel.
An example of an abnormally low delta-p limiter: During start-up, if the valve is operating under low differential pressure, and the valve indicates a "flow not reached" condition, but the valve position is less than 1.2 radians, then the valve position is being limited by the table values as described above. This situation can generally be resolved by increasing the valve inlet pressure to increase the differential pressure across the valve.
SAE J1939 Communications with Woodward EGS-02
The TecJet 52 devices support CAN communications in the SAE J1939 Higher Layer Protocol format. Further detailed information regarding the J1939 Standards Collection can be purchased at www.sae.org. Information about CAN can be found at www.semiconductors.bosch.de. Specific information regarding TecJet 52 behavior is detailed below.
All TecJet 52 J1939 messages use the CAN 2.0B 29-bit Extended Data Frame Format.
Figure 3-1. Address Claimed State Chart
General Specifications
Electrical Input Characteristics
Mechanical Characteristics
Fuel Connections
Dynamics
Environmental
EMC
EN61000-6-2 (2005): Immunity for Industrial Environments
EN61000-6-4 (2001): Emissions for Industrial Environments
Fuel Type
The TecJet 52 operates on gases ranging from pipeline quality natural gas to specialty gas (such as landfill, digester, or other biogases). The TecJet 52 operates on gases ranging from pipeline quality natural gas to propane. Proper application of the valve for fuel flow, FGP, energy content, etc., is the responsibility of the OEM/packager/customer. The fuel gas flowing through the valve can consist of the following compounds with limits if they apply:
Component and Specification
Overall the gas specific Gravity should be between 0.4 and 2.0 for the TecJet 52. The energy content should be between 1 and 9.5 kwh/nm3. The values in () are allowed, but may result in reduced valve life. The above fuel limits can be converted to ppm by multiplying the given number by the LHV of the fuel in question, then dividing by 36. The LHV must be in units of MJ/kg.
Pressures
Inlet fuel gas pressure (FGP) should normally be between 876 and 1289 mbar absolute. Keep in mind that for a given gauge FGP value, absolute FGP will decrease with increasing altitude above sea level. The inlet FGP sensor will compensate for barometric pressure to 3000 m. Pressures below 876 mbar are allowed at high load operation assuming that the gas differential pressure requirements are still met.
The TecJet 52 fuel gas differential pressure (delta-p) should be between 69 and 345 mbar. Delta-P below this range is allowed during cranking and idle conditions, but accuracy of the valve will be reduced. For delta-p above 276 mbar, flow accuracy will also decrease, and a reduction in valve stability may occur. Refer to the accuracy section later in this chapter for further details.
Minimum proof pressure for the TecJet 52 is 0.52 bar gauge. Minimum burst pressure for the TecJet 52 is 1.72 bar gauge.
Temperature
The following are the temperature specifications for the TecJet 52:
- * Steady State Ambient Temperature: -20 to +85° C (-4 to +185° F)
- * Long Term Storage Temperature: -40 to +45° C (-40 to +113° F)*
- * Short Term Storage Temperature: -40 to +105° C (-40 to +221° F)*
- * Fuel Gas Inlet Temperature: 0 to 65° C (32 to 149° F)
- * Long Term Storage Temperature: -40 to +45° C (-40 to +113° F)*
*The unit is un-powered during storage temperature.
Vibration and Shock
- Random Vibration: Exceeds WGC RV2, 10-2000 Hz @ 0.1 G2/Hz (12.8 Grms)
- Shock: Per US MIL-STD-810C, Method 516.2, Procedure 1, (40 g)
Ingress Protection
IP56 per IEC 60529, (Dust ingress, water ingress)
Flow Characteristics
Accuracy
The TecJet 52 meters fuel accurately such that the engine starts consistently and accelerates smoothly to idle speed. The required fuel delivery up to 7% of valve maximum rated effective area is within ±20% of the mass flow demand. Throughout the load range, from idle to 100% load, the TecJet 52 regulates the fuel delivery accurately relative to the fuel flow demand in order to reduce combustion emissions and protect the engine against detonation. The accuracy is within ±10% of the mass flow demand from >7% to 25% of valve maximum rated effective area and within ±6% of the mass flow demand above 25% of valve maximum rated effective area.
For delta-p above 275 mbar, an additional 1.5%, 1%, and 0.5%, respectively, should be added to the accuracy values stated above. Delta pressure below the minimum specified delta pressure would also significantly affect the accuracy values stated above.