Precision XVG Fuel Valve

User Manual

XVG / eXVG Series Gas Fuel Metering Valve

SD-6011 Rev 5

September 2009

PRECISION ENGINE CONTROLS CORPORATION

This manual provides installation, maintenance, and operating instructions for the XVG/eXVG Series of Gas Fuel Metering Valves.

Every attempt has been made to provide sufficient information in this manual for the proper operation and preventive maintenance of the gas fuel-metering valve. Read this manual in its entirety to fully understand the system.

Operating the XVG/eXVG Gas Fuel Metering Valve in accordance with instructions herein ensures long term and reliable operation.

If you need additional information, please contact:

Marketing Department

Precision Engine Controls Corporation 11661 Sorrento Valley Road San Diego, California 92121

(858) 792-3217 • (800) 200-4404

Fax: (858) 792-3200 E-mail: [email protected]

© 2007 PRECISION ENGINE CONTROLS CORPORATION. ALL RIGHTS RESERVED

TABLE OF CONTENTS Purpose of This Guide ................................................................................................................................... iv What the User Should Know ......................................................................................................................... iv Related Publications....................................................................................................................................... iv

1 INSTALLING THE XVG/eXVG .................................................................................................................. 1 1.1 Before Beginning..................................................................................................................................... 1 1.2 General Specification Summary............................................................................................................. 3 1.3 Mechanical Installation............................................................................................................................ 4 1.4 Electrical Connections............................................................................................................................. 11

2 UNDERSTANDING THE XVG/eXVG ....................................................................................................... 27 2.1 System Description ................................................................................................................................. 27 2.2 Versions of the XVG/eXVG .................................................................................................................... 28 2.3 Operating Modes of XVG/eXVG ............................................................................................................ 37 2.4 Mechanical Functional Description ........................................................................................................ 38 2.5 Electrical Functional Description ............................................................................................................ 41 2.6 Identification Plate ................................................................................................................................... 43

3 OPERATING THE XVG/eXVG.................................................................................................................. 47 3.1 Performance Factors............................................................................................................................... 47 3.2 Operating Modes..................................................................................................................................... 49 3.3 Feedback................................................................................................................................................. 53 3.4 Monitoring System Health....................................................................................................................... 55

4 MAINTAINING THE XVG/eXVG................................................................................................................ 58 4.1 Preventive Maintenance ......................................................................................................................... 58 4.2 Corrective Maintenance.......................................................................................................................... 60 4.3 Calibration................................................................................................................................................ 65 4.4 Refurbishment ......................................................................................................................................... 65

5 TROUBLESHOOTING THE XVG/eXVG .................................................................................................. 66 5.1 Electrical Troubleshooting....................................................................................................................... 66 5.2 Retrieving The Fault File......................................................................................................................... 67 5.3 Fault Diagnosis........................................................................................................................................ 68

APPENDIX A: DECOMMISSIONING & DISPOSAL ...................................................................................... 75

PREFACE i

LIST OF FIGURES Figure 1-1. Typical XVG/eXVG Gas Fuel System Installation ...........................................5 Figure 1-2. Alternate XVG/eXVG Gas Fuel System Installation ........................................5 Figure 1-3. XVG Dimensions ...............................................................................................7 Figure 1-4. eXVG Dimensions .............................................................................................7 Figure 1-5. XVG/eXVG Dimensions with Harness as Electrical Interface (XVG shown) .8 Figure 1-6. XVG Mounting Provisions .................................................................................9 Figure 1-7. eXVG Mounting Provisions ...............................................................................9 Figure 1-8. Wire Harness Connector for XVG/eXVG .......................................................11 Figure 1-9. Terminal Blocks for XVG/eXVG......................................................................12 Figure 1-10. Recommended Type of Explosion-Proof Connector (with wires shown)...13 Figure 1-11. Ground Connections for XVG/eXVG............................................................14 Figure 1-12. Power Connection to Solenoid for XVG/eXVG............................................15 Figure 1-13. Power Connection to Electronics for XVG/eXVG........................................16 Figure 1-14. Typical Analog Input Current Connection ....................................................18 Figure 1-15. Typical Analog Input Voltage Connection ....................................................18 Figure 1-16. Typical Analog Output Current Connection .................................................19 Figure 1-17. Typical Analog Output Voltage Connection .................................................19 Figure 1-18. Typical Discrete Input Command Connection .............................................20 Figure 1-19. Typical Discrete Output Alarm Connection ..................................................20 Figure 1-20. Typical RS232 Serial Interface Connection .................................................21 Figure 1-21. Typical RS232 Serial Interface Connection .................................................22 Figure 1-22. Wiring Shield Connections............................................................................25 Figure 2-1. Cross-sectional view of XVG/eXVG. ..............................................................28 Figure 2-2. Dynamic seal and scraper of XVG/eXVG. .....................................................29 Figure 2-3. Product Definition Number Details (sample)..................................................31 Figure 2-4. Exploded View of the XVG/eXVG...................................................................40 Figure 2-5. Partial Cutaway View of Breather Vent ..........................................................40 Figure 2-6. XVG/eXVG Electronics System Block Diagram ............................................42 Figure 2-7. Typical Identification Plate for XVG, p/n 5002800-001 or -002.....................44 Figure 2-8. Typical Identification Plate for eXVG, p/n 5002800-003 or -004...................44 Figure 2-9. Typical Identification Plate for XVG, p/n 5002801-001 or -002.....................45 Figure 2-10. Typical Identification Plate for eXVG, p/n 5002801-003 or -004.................45 Figure 3-1. Stroke vs. Fuel Demand Curve.......................................................................50 Figure 3-2. Flow Rate vs. Fuel Demand Curve.................................................................52 Figure 3-3. Flow Rate vs. Outlet Pressure Curve (example) ..........................................54

II XVG/eXVG USER MANUAL

Figure 4-1. XVG Orifice Plate Removal.............................................................................62 Figure 4-2. eXVG Orifice Plate Removal...........................................................................62 Figure 4-3. XVG Orifice Plate.............................................................................................64 Figure 4-4. eXVG Orifice Plate...........................................................................................64

LIST OF TABLES Table 1-1. Connection List for XVG/eXVG Solenoid Power ............................................15 Table 1-2. Connection List for XVG/eXVG Electronics Power.........................................15 Table 1-3. Power Supply Requirements............................................................................16 Table 1-4. Signal Connections for XVG/eXVG, p/n 5002800-00x...................................17 Table 1-5. Signal Connections for XVG/eXVG, p/n 5002801-00x...................................17 Table 1-6. Computer COM Port Pin Outs .........................................................................21 Table 1-7. Computer COM Port Pin Outs .........................................................................22 Table 1-8. Recommended Wire Size for Harness............................................................23 Table 2-1. Part Numbers for XVG/eXVG ..........................................................................29 Table 2-2. Model Numbers and Types..............................................................................30 Table 2-3. Operation Mode Configuration.........................................................................31 Table 2-4. Command (AICH0) Signal Configuration ........................................................32 Table 2-5. Analog Output Parameter Channel Configuration ..........................................33 Table 2-6. Analog Output Signal Configuration ................................................................33 Table 2-7. Gas Constants Configuration...........................................................................34 Table 2-8. Max Flow Configuration....................................................................................35 Table 2-9. Calibration Curve ..............................................................................................35 Table 2-10. Electrical Interface...........................................................................................36 Table 2-11. Flange Interface ..............................................................................................36 Table 3-1. Command (AICH0) Signal Configurations ......................................................47 Table 3-2. Command Signal Percentage Values .............................................................48 Table 3-3. Maximum Flow Area for XVG/eXVG ...............................................................49 Table 3-4. Feedback (AOCH0 or AOCH1) Signal Configurations...................................54 Table 3-5. Feedback Parameter Configuration.................................................................55 Table 5-1. XVG/eXVG Expected Circuit Impedance........................................................67 Table 5-2. XVG/eXVG Initial Installation Troubleshooting Chart......................................69 Table 5-3. XVG/eXVG In-Service Troubleshooting Chart ................................................70 Table 5-4. System Health Parameters and Limits ............................................................72

PREFACE iii

IV XVG/eXVG USER MANUAL

Purpose of This Guide

This publication is designed to help the user install, operate, maintain and troubleshoot the XVG/eXVG Gas Fuel Metering Valve.

What the User Should Know

To install, operate and troubleshoot the XVG/eXVG Gas Fuel Metering Valve, it is necessary for the user to have a fundamental understanding of:

• Electronics concepts, such as voltage, current, and switches

• Mechanical motion control concepts, such as inertia, torque, velocity, distance, force

Related Publications

• XView Software Operation Manual (SD-6014)

1 INSTALLING THE XVG/eXVG

1.1 Before Beginning

Inspection The XVG/eXVG should be inspected immediately after unpacking. Check for dings or dents or any other obvious signs of damage. Remove the protective plug from the port for the wire harness (for Terminal Block Electrical Interface option only) and check for any damage to the threads. Examine the wire harness (for Wire Harness Electrical Interface options only) for any signs of damage to the wire insulation.

In the event that any damage is detected, contact Precision Engine Controls Corporation (PECC).

Note: Retain the metering valve’s original shipping container. In the event of future transportation requirements, this container will minimize any damage during shipment.

Recommended Installation Process

• Review the general specifications

• Mechanically connect the XVG/eXVG to the mounting surface

• Connect Case Ground of the XVG/eXVG to System Ground

• Remove the top cover of the XVG/eXVG per the instructions in Figure 1-11 (for Terminal Block Electrical Interface option only)

• Connect the XVG/eXVG’s + and – terminals or wires for the Solenoid and Electronics 24VDC inputs to the user’s power supplies or batteries

• Connect the discrete and analog inputs and outputs of the XVG/eXVG to the user’s controller

• Test the installation

CH. 1: INSTALLING THE XVG/eXVG 1

Electrical Noise Guidelines PECC has taken the following measures to reduce electrical noise with the XVG/eXVG:

• Filtering was added in the signal processing circuits.

• Components in critical circuits were positioned to minimize susceptibility.

An additional measure to reduce electrical noise is to:

• Ensure that the XVG/eXVG is properly grounded, as per Section 1.4, Figure 1-11 of this manual.

Environmental Considerations The XVG/eXVG operates satisfactorily with an ambient air temperature of -40 °C (-40 °F) to +93 °C (+200 °F). The XVG/eXVG enclosure is Canadian Standards Association (CSA) Type 4, European IP56.

2 XVG/eXVG USER MANUAL

1.2 General Specification Summary PARAMETER VALUE Power Input

Input Voltage, Nominal 24 VDC

Minimum Voltage 16 VDC

Maximum Voltage 32 VDC (maximum value for combined VDC and VAC components)

Maximum Ripple 2 VAC

Peak Current Solenoid: 10A Electronics: 1A

Continuous Current Solenoid: 5A Maximum, 1.5A typical Electronics: 0.5A Maximum, 130 mA typical

Inputs and Outputs

Analog Inputs

Current: 4 to 20 mA; 40 mA Maximum Voltage: 0 to 5 VDC; 8 VDC Maximum Input Impedance: 246 Ω in Current Mode, 16.7k Ω in Voltage Mode

Analog Outputs

Current: 4 to 20 mA Voltage: 0 to 5 VDC Load Resistance: 300 Ω Max in Current Mode, 250 Ω Min in Voltage Mode

Discrete Inputs

ON Voltage: 12 – 32 VDC, +24 VDC Nominal ON Current: 1.5 mA Nominal @ 24 VDC OFF Voltage: 3.5 VDC, Maximum OFF Current: 0.75 mA, Maximum

Discrete Outputs

OFF Voltage: 32 VDC, Maximum OFF Resistance: 200,000 Ω Minimum ON Resistance: 900 to 1100 Ω ON Voltage: 32 VDC Maximum

Maximum Common Mode Voltage ±200 VDC User I/O to 24 VDC Return

Communication

Hardware RS-232 or RS-485 (optional)

Software Protocol PECC or Modbus

Baud Rate (bps) 9600, 18200, 38400, or 57600

Performance

Maximum Operating Pressure XVG: 435 psig eXVG: 500 psig

Proof Pressure XVG: 1740 psig eXVG: 2000 psig

Minimum Delta P 0 psid (stroke mode), 20 psid (flow control mode)

Min. Controllable Flow (Natural Gas @ 59°F) 12 lbm / hour

Max. Controllable Flow (Natural Gas @ 59°F under sonic flow conditions, Pin >1.9 Pout)

XVG: 15,000 lbm /hour eXVG: 20,000 lbm /hour

Step Response (10% to 90%) <100ms

Flow Accuracy ±3% of full scale, typical

Mean Time Before Failure 30,000 Hours

Environmental

Temperature, Operating Ambient -40° C (-40° F) to +93° C (+200° F)

Temperature, Operating Fuel -20° C (-4° F) to +93° C (+200° F)

Temperature, Storage -40° C (-40° F) to +125° C (+257° F)


Environmental Rating Rated to NEMA 4 and European IP56

Humidity Meets Mil-Std-810F, 95% Relative Humidity (Non-Condensing)

Vibration and Shock Meets Mil-Std-810F, Vibration Category 22 (5 – 2000 Hz) Meets Mil-Std-810F, Functional Shock, 20g peak, 11 ms duration Meets Mil-Std-810F, Transit Drop

Certifications

North American Certifications CSA (Canada and US) Class I, Div 1, Group B, C, D; T4. File # 171042

European Directive Compliance (CE Mark)

II2G EEx d, IIB+H2; T4 97/23/EC Pressure Equipment Directive (PED) 94/9/EC Potentially Explosive Atmospheres (ATEX) KEMA 04ATEX2326 98/37/EC Machinery Directive 89/336/EEC Electromagnetic Compatibility Directive (EMC) Group 1 Class A EN 50081-2 Emission EN 61000-6-25 Immunity

Materials

Housing 6061-T6 Anodized Aluminum 316 Stainless Steel (Optional)

Seals PTFE and Viton®

Dimensions XVG: 9.08 in x 5.80 in x 6.75 in eXVG: 9.08 in x 7.70 in x 6.75 in

Weight XVG: 36 lbs. Max (Aluminum), ~74 lbs. (Stainless Steel) eXVG: 38 lbs. Max (Aluminum), ~82 lbs. (Stainless Steel)

1.3 Mechanical Installation

This section describes proper XVG/eXVG installation. Ensure compliance with the factory recommendations.

Typical Fuel System The XVG/eXVG installs as part of a gas fuel system as shown in Figure 1-1. In this arrangement, the XVG/eXVG is located downstream from two normally closed gas shut-off valves.

An alternate arrangement is shown in Figure 1-2. In this installation, the XVG/eXVG is located between two normally closed gas shut-off valves.


Figure 1-1. Typical XVG/eXVG Gas Fuel System Installation

Figure 1-2. Alternate XVG/eXVG Gas Fuel System Installation

Fuel Filtering

For efficient valve operation, filter the fuel through a 40-micron absolute filter before it reaches the valve. This extends the time between routine maintenance. Locate the fuel filter as close as possible to the valve INLET.

Dimensions Figure 1-3 and Figure 1-4 show external dimensions for the XVG and eXVG, respectively.

Mounting Considerations The XVG/eXVG includes four (4) 5/16-24 UNF-3B mounting holes with stainless steel heli-coil inserts for securing the controller enclosure. See Figure 1-6 and Figure 1-7 for details about placement of mounting holes.

The XVG/eXVG can be mounted with any directional orientation, whether horizontal, vertical, or at an angle. However, PECC recommends the XVG/eXVG be mounted such that the “Flow” arrow on the body of the unit (see Figure 1-6) is pointing up or down. This orientation has the solenoid


operating along a vertical axis and will thus reduce wear on the XVG/eXVG.

High strength bolts (0.3125in. diameter) are required to secure the controller enclosure to a user-provided mount bracket.

Note: Ensure adequate clearance is provided to the OUTLET and to the electronics cover to facilitate installation and maintenance.


Figure 1-3. XVG Dimensions

Figure 1-4. eXVG Dimensions


Note: To maintain flow control accuracy, ten-(10) pipe diameters (15 inches) straight length minimum is recommended upstream and downstream.

The aluminum-body XVG weighs approximately 36 lbs. The aluminum-body eXVG weighs approximately 38 lbs. PECC recommends the use of lifting equipment to lift the valve.

WARNING - Lift Hazard

Use special care when lifting by hand. Serious back injury may result without appropriate lifting equipment.

Figure 1-5. XVG/eXVG Dimensions with Harness as Electrical Interface

(XVG shown)


Figure 1-6. XVG Mounting Provisions

Figure 1-7. eXVG Mounting Provisions


Pipe Connections The standard pipe connections for the XVG/eXVG are:

• XVG = SAE J518 -24 (1.5 inch), code 61

• eXVG = SAE J518 -32 (2.0 inch), code 61

The valve bodies contain locking helical inserts. Contact Precision Engine Controls Corporation for other connection options.

Note: Use only SAE conforming mating connections. Use of non-conforming connections may change valve calibration.

Note: To maintain flow control accuracy, ten-(10) pipe diameters (15 inches) straight length minimum is recommended upstream and downstream.

Flange Bolts

Precision Engine Controls Corporation recommends the following bolts and torque values:

• XVG = 1/2 – 13 x 1-1/2, UNC-2A SAE Grade 5 or better.

• eXVG = 1/2 – 13 x 1-3/4, UNC-2A SAE Grade 5 or better

Torque to 550 – 700 in-lb.

WARNING - Fuel Leakage Hazard

Do not over-torque fittings. Stripped threads or helical insert damage may result.


1.4 Electrical Connections The XVG/eXVG is suitable for use in hazardous locations. See the General Specification Summary in Section 1.2 for certifications. Ensure compliance with the factory recommendations, and that wiring is in accordance with local requirements.

Electrical Interface Options The XVG/eXVG is available in configurations with either an integral wire harness or internal terminal blocks as the electrical interface.

Wire Harness Option

The XVG/eXVG is available with an integral 13-wire or 15-wire pigtail harness as the electrical interface. The 13-wire harness is used with the basic configurations of the XVG/eXVG. The 15-wire harness is used in those configurations that require a second analog output channel. See Figures 1-5 and 1-8 for representations of the wire harness connector. See Section 2.2 for details about XVG/eXVG configurations.

Figure 1-8. Wire Harness Connector for XVG/eXVG


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Terminal Block Option

The XVG/eXVG is available in configurations with internal terminal blocks as the electrical interface. The top cover of the XVG/eXVG must be removed to access the terminal blocks. See Figure 1-9 for a view of the terminal blocks. See Figure 1-11 for cover-removal and installation instructions.

Cutouts in heat sinkto allow access to

terminal blocksTerminal Blocks

InternalGround Lug

Port ForWire Harness3/4 in. NPT

External Ground Lug

TOP VIEWCover Removed

Figure 1-9. Terminal Blocks for XVG/eXVG

Any XVG/eXVG with the terminal blocks as the electrical interface features a threaded entry port (3/4in. NPT) to allow wiring between the electronics enclosure of the unit and the power supplies and controller. The XVG/eXVG is shipped with a plastic cap filling this entry port to prevent foreign matter from entering the electronics enclosure.


Note: It is important that the cover and enclosure surfaces are free from scoring and that the cover bolts are tightened with the proper torque to maintain the explosion-proof rating.

Prior to installing a conduit into the threaded port, wrap Teflon tape on the male threads of the conduit to ensure an adequate seal. Tape should cover the entire thread area, with no more than two layers of tape on the threads. The conduit should be tightened to a minimum of 45 ft-lbs. of torque, with at least 5 full threads on the conduit engaged,

Explosion-Proof Wiring Installation

An explosion-proof seal, such as a hazardous location fitting or conduit box with an approved seal, must be provided within 18 inches of the wire entry port to comply with Canadian Standards Association (CSA), Class I, Division 1, Group B, C and D requirements. This seal must also be provided at the electronics enclosure wire entry per European Union (EU) ATEX standards. The seal must be compliant and installed per local European Union requirements. See Figure 1-10 for the recommended type of explosion-proof connector for the XVG/eXVG.

Figure 1-10. Recommended Type of Explosion-Proof Connector (with wires

shown)

Ground Connections The case of the XVG/eXVG features an external lug that is attached to the housing with a screw and washers. This grounding lug is located on the output side of the unit, just below the top cover, and it is unlabeled. See Figure 1-11 for details and connection instructions. The grounding lug, screw, and washers are provided.

The XVG/eXVG also features an internal grounding lug for those versions that use the internal terminal blocks as the electrical interface. See Figure 1-11 for details and connection instructions.


Figure 1-11. Ground Connections for XVG/eXVG


Power Connections The XVG/eXVG requires two power connections.

• To the Solenoid

• To the Electronics

Power Connection to Solenoid

The solenoid of the XVG/eXVG operates on a 24VDC (nominal), user-provided input voltage. This voltage is supplied to the unit through either the integral wire harness or the terminal blocks, depending on the Electrical Interface configuration (see Section 2.2 for details).

FUNCTION WIRE COLOR TERM. # Solenoid Power ORANGE 19

Solenoid Return RED 20

Table 1-1. Connection List for XVG/eXVG Solenoid Power

Figure 1-12. Power Connection to Solenoid for XVG/eXVG

Power Connection to Electronics

The electronics of the XVG/eXVG operate on a 24VDC (nominal), user-provided input voltage. This voltage is supplied to the unit through either the integral wire harness or the terminal blocks, depending on the Electrical Interface configuration (see Section 2.2 for details).

FUNCTION WIRE COLOR TERM. # Electronics Power VIOLET 21

Electronics Return BLUE 22

Table 1-2. Connection List for XVG/eXVG Electronics Power


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Figure 1-13. Power Connection to Electronics for XVG/eXVG

WARNING

The user must ensure proper 24 VDC electronics power levels, because the XVG/eXVG will NOT produce a fault signal if the 24 VDC electronics input power voltage is outside the specified range.

Power Supply Requirements

Table 1-3 below lists the power supply requirements for the XVG/eXVG.

PARAMETER SOLENOID Value

ELECTRONICS Value

Voltage Nominal Minimum Maximum

24 VDC 16 VDC 32 V (see Note)

24 VDC 16 VDC 32 V (see Note)

Ripple 2 VAC p-p, max 2 VAC p-p, max

Current Maximum Continuous , Max Continuous, Typical

10 Amps 5 Amps 1.5 Amps

1 Amp 0.5 Amps 130 mA

Table 1-3. Power Supply Requirements

Note: The maximum voltage specification includes both DC and AC (from ripple) components.


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Signal Connections The XVG/eXVG transmits and receives signals through either the integral wiring harness or the terminal blocks, depending on the Electrical Interface configuration (see Section 2.2 for details).

Signal Connections to User’s Controller

Signals are sent between the XVG/eXVG and the user’s controller through the integral 13-wire or 15-wire signal harness or through the internal terminal blocks. See Tables 1-4 and 1-5 for the wire lists for these harnesses, as well as the corresponding terminal numbers.

FUNCTION WIRE COLOR TERMINAL # AICH0 (Demand) BROWN 1

AICH0 RTN (Demand RTN) GREEN 2

AOCH0 (Feedback) YELLOW 13

AOCH0 RTN (Feedback RTN) BLACK 14

FAULT ALARM WHITE / ORANGE 31

FAULT RTN WHITE / BLACK / ORANGE 32

Serial/TX Out A WHITE / ORANGE / BLUE 39

Serial/RX In A WHITE / ORANGE / YELLOW 40

Serial RETURN A WHITE / ORANGE / GREEN 41

Table 1-4. Signal Connections for XVG/eXVG, p/n 5002800-00x

FUNCTION WIRE COLOR TERMINAL # AICH0 (Demand) BROWN 1

AICH0 RTN (Demand RTN) GREEN 2

AOCH0 (Feedback) YELLOW 13

AOCH0 RTN (Feedback RTN) BLACK 14

AOCH1 WHITE 15

AOCH1 RTN GREY 16

FAULT ALARM WHITE / ORANGE 31

FAULT RTN WHITE / BLACK / ORANGE 32

Serial/TX Out A WHITE / ORANGE / BLUE 39

Serial/RX In A WHITE / ORANGE / YELLOW 40

Serial RETURN A WHITE / ORANGE / GREEN 41

Table 1-5. Signal Connections for XVG/eXVG, p/n 5002801-00x


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Nota

Nuestra configuración es de 15 cables porque tengo 5 señales.

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Note: For proper operation of the controller, the common mode voltage between the control inputs and the power inputs shall be less than 200 VDC.

Analog Inputs

The base XVG/eXVG configuration includes one analog input channel, A/I CH0, which is dedicated as the Demand signal. Additional analog input channels may be available as options (contact PECC for details).

The XVG/eXVG can be configured to accept the analog input signals in either current form or voltage form.

The current range for an analog input is 4 to 20 mA, where 4mA corresponds to a command of 0% and 20 mA corresponds to a command of 100%. See Figure 1-14 for a typical analog input current connection.

The XVG/eXVG features two voltage configurations for the analog input channels. The voltage range for analog inputs is 0 to 5 VDC, where 0 VDC corresponds to a command of 0% and 5VDC corresponds to a command of 100%. The other voltage range for analog inputs is 1 to 5VDC, where 1 VDC corresponds to a command of 0% and 5VDC corresponds to a command of 100%. See Figure 1-15 for a typical analog input voltage connection.

Figure 1-14. Typical Analog Input Current Connection

CONTROLLER 0-5V OUTPUT

ANALOG IN RETURN

ANALOG IN OVER

SUPPRESSOR

VOLTAGEPROTECTIONTRANSIENT

VOLTAGE

+

-

16.7K+

-

XVG/eXVG0-5V INPUT

Ω

Figure 1-15. Typical Analog Input Voltage Connection


Analog Outputs

The base XVG/eXVG configuration includes one analog output channel, AOCH0, which is dedicated as the Feedback signal. The XVG/eXVG version with pressure sensors (p/n 5002801-00x) provides an additional analog output, AOCH1, for feedback. See Section 2.2 for details about different versions of the XVG/eXVG. Each analog output signal can be independently configured for either current form or voltage form.

The current range for the analog outputs is 4 to 20 mA, where 4mA corresponds to an output signal of 0% and 20 mA corresponds to an output signal of 100%. See Figure 1-16 for a typical analog output current connection.

The XVG/eXVG features three voltage configurations for the analog output channels. The first voltage range for analog outputs is 0 to 5 VDC, where 0 VDC corresponds to an output signal of 0% and 5VDC corresponds to an output signal of 100%. The second voltage range for analog outputs is 1 to 5VDC, where 1 VDC corresponds to an output signal of 0% and 5VDC corresponds to an output signal of 100%. See Figure 1-16 for a typical analog output current connection. The third voltage range for analog outputs is 0 to -5 VDC, where 0 VDC corresponds to an output signal of 0% and -5VDC corresponds to an output signal of 100%. See Figure 1-17 for a typical analog output voltage connection.

Figure 1-16. Typical Analog Output Current Connection

Figure 1-17. Typical Analog Output Voltage Connection


Discrete Inputs

The discrete input channel D/I CH0 is dedicated as the Run/Stop command signal. D/I CH0 is shown on the nameplate but it is only available as an option. Additional user-definable, discrete input channels may also be available as options (contact PECC for details).

The discrete inputs are 24 VDC ON (High) and 0 VDC OFF (Low). See Figure 1-18 for a typical discrete input connection.

Figure 1-18. Typical Discrete Input Command Connection

Discrete Outputs

The base XVG/eXVG configuration includes one discrete output channel, D/O CH0, which is dedicated as the FAULT ALARM signal. Additional user-definable, discrete output channels may be available as options (contact PECC for details).

The discrete outputs are solid-state switches, which are normally closed. The control system provides a current-limited voltage bias of 24 VDC. See Figure 1-19 for a typical discrete output connection.

XVG/eXVG DISCRETE OUTPUTDISCRETE OUT

CONTROLLER DISCRETE INPUT

DISCRETE OUT RTN24VDC

Figure 1-19. Typical Discrete Output Alarm Connection

RS232 Serial Communications Interface

Signal levels for the serial communications input and output are per RS232 standards. See Figure 1-20 for a typical RS232 interface connection. See Table 1-6 for computer COM port pin-outs for RS232.


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XVG/XVG/eXVG SERIAL INTERFACE

RTN

COMPUTER

Rx

Tx

(WHT/ORN/GRN) [TERM #41]

(WHT/ORN/BLU) [TERM #39]

(WHT/ORN/YEL) [TERM #40]

COM1

RTN

Tx

Rx TRANSCEIVER

Figure 1-20. Typical RS232 Serial Interface Connection

FUNCTION Standard 9-Pin COM Port

Standard 25 -Pin COM Port

Transmit (Tx) Pin 3 Pin 2

Receive (Rx) Pin 2 Pin 3

Ground (GND) Pin 5 Pin 7

Table 1-6. Computer COM Port Pin Outs

Note: The pin designations shown in Table 1-6 are for the COM port on the computer. Make sure that the wiring to the COM port mating connector correctly matches Transmit from the XVG/eXVG to Receive on the computer’s COM port, and vice versa.

Note: The maximum distance for RS232 serial connections is 50 ft. This will typically only allow for local interface with a laptop PC.

RS485 Serial Communications Interface (Optional)

Signal levels for the serial communications input and output are per RS485 standards. See Figure 1-21 for a typical RS485 interface connection. See Table 1-7 for computer COM port pin-outs for RS485.


B

A

(WHT/ORN/GRN) [TERM #41]

(WHT/ORN/BLU) [TERM #39]

(WHT/ORN/YEL) [TERM #40]

COM1

SERIAL A

SERIAL BXVG/eXVG SERIAL INTERFACE

X

TRANSCEIVER

Figure 1-21. Typical RS485 Serial Interface Connection

FUNCTION Standard 9-Pin COM Port

Standard 25 -Pin COM Port

Serial A Pin 3 Pin 2

Serial B Pin 2 Pin 3

Table 1-7. Computer COM Port Pin Outs

Note: The pin designations shown in Table 1-7 are for the COM port on the computer. Make sure that the wiring to the COM port mating connector correctly matches Serial A from the XVG/eXVG to Serial A on the computer’s COM port.

Note: The maximum distance for RS485 serial connections is 4000 ft at 57.6 kbps.

Recommended Wiring The recommended wiring is an 18-conductor shielded cable containing twisted-pair wires with individual shields.

Ensure that all shielded cables are twisted conductor pairs with either a foil or braided shield. PECC recommends Belden 9332 shielded twisted-pair audio, broadcast and instrumentation cable. All signal lines should be shielded to prevent picking up stray signals. Connect shields as shown in Figure 1-22. Wire exposed beyond the shield should be as short as possible.


natalia.pachon

Resaltar

The maximum resistance for the solenoid power loop should be one (1) ohm. The maximum resistance for the electronics power loop should be five (5) ohms. The maximum resistance for the signal wire loop should be ten (10) ohms.

See Table 1-8 for recommended wire sizes.

DISTANCE TO USER’S POWER / CONTROLLER

SIGNAL WIRE SIZE (Minimum)

POWER WIRE SIZE (Minimum)

GROUND WIRE SIZE (Minimum)

1 to 125 ft. AWG 22, stranded AWG 16, stranded AWG 16, stranded

125 to 500 ft. AWG 16, stranded AWG 10, stranded Not Recommended

500 to 1000 ft. AWG 14, stranded AWG 7, stranded Not Recommended

> 1000 ft. Not Recommended Not Recommended Not Recommended

Table 1-8. Recommended Wire Size for Harness

Note: The XVG/eXVG terminal blocks will accept wire sizes from 18 AWG to 22 AWG. An external junction box must be used if larger diameter wire is required.


natalia.pachon

Resaltar

CAUTION

This valve is 89/339/EEC EMC Directive compliant (CE mark) using watertight, flexible conduit (plastic over steel) and Belden 9332 shielded, twisted pair-audio, broadcast and instrumentation cable. Use of other conduit or wire invalidates EMC Directive compliance.

Do not connect 24 VDC power without current limiting (25 mA) across digital or analog outputs.


Figure 1-22. Wiring Shield Connections



INTENTIONALLY BLANK

2 UNDERSTANDING THE XVG/eXVG

2.1 System Description The XVG/eXVG is an electrically operated gas fuel-metering valve that requires only 24 VDC power and an analog fuel Demand signal to achieve basic operational capability. No pneumatic or hydraulic power is required.

The flow tube and armature assembly is the only moving part in the system. A solenoid and return spring combination is used to move the flow tube assembly. Flow is metered between the flow tube and output orifice in proportion to the flow tube position and resultant flow area. The flow area ranges from zero with a Demand signal at 0% of its range to maximum with a Demand signal at 100% of its range. See Figure 2-1 to view the flow tube assembly and solenoid. A scraper and dynamic seals are located around the flow tube to prevent the gas from entering the housing assembly (see Figure 2-2). The flow tube closes around the orifice seal when the fuel Demand signal is 0% or when solenoid power is removed.

The XVG/eXVG is a force-balanced system. A solenoid actively provides electro-magnetic force to open the valve based on the relative strength of the Demand signal. This is counter-balanced by a return spring that passively provides mechanical force to close the valve. The gas pressure is balanced across the flow tube such that the solenoid force primarily acts against the return spring.

When the Demand signal level increases, the solenoid provides additional force on the flow tube assembly. The solenoid is now exerting more force than the return spring, so the valve opens further until the spring force is balanced with the solenoid force.

When the Demand signal level decreases, the solenoid provides less force on the flow tube assembly. The solenoid is now exerting less force than the return spring, so the valve closes further until the spring force is balanced with the solenoid force.

The return spring acts as a fail-safe. It stores enough energy to fully close the valve when Demand drops to a level corresponding to the 0% position or if power to the solenoid or electronics is removed.

A linear variable differential transformer (LVDT) is directly connected to the flow tube and provides tube-positioning feedback to the control loop in the digital signal processor (DSP) to ensure accurate tube placement.

CH. 2: UNDERSTANDING THE XVG/eXVG 27

Optional pressure sensors at the input and output ports provide the ability to determine flow. The XVG/eXVG can also be configured to track the fuel Demand signal in proportion to measured mass flow. Another optional configuration limits fuel mass flow by scaling the fuel Demand signal according to pre-programmed maximum and minimum fuel limit levels. See Section 3: Operating Modes of XVG/eXVG for details.

Figure 2-1. Cross-sectional view of XVG/eXVG.

2.2 Versions of the XVG/eXVG Two numbers describe the configuration of a given XVG/eXVG:

• Part Number

• Product Definition Number (PDN)


Figure 2-2. Dynamic seal and scraper of XVG/eXVG.

Part Numbers The part number for the XVG/eXVG is made up of two parts: the base part number and the extension. For example, the part number 5002800-001 has a base part number of “5002800” and an extension of “-001”

Base Part Number

The part number designates the specific version and corresponding bill of material used to manufacture the XVG/eXVG. See Table 2-1

Base Part # Description Application

5002800

This is the baseline model of the XVG/eXVG. The Demand signal is used to directly modulate the flow tube assembly position. Flow is metered between the flow tube and outlet orifice in proportion to flow tube position and resultant flow area. Includes only one analog output channel.

Fuel Regulation

5002801

This is mechanically equivalent to the baseline model with the addition of pressure sensors at the inlet port and outlet port. Includes two analog output channels.

Flow Measurement

Flow Control

Flow Limiting

Table 2-1. Part Numbers for XVG/eXVG


Extension Numbers

The XVG/eXVG is available in two different models: the XVG and the eXVG. The XVG is the base model. The eXVG is the larger flow-capacity model.

The physical differences between the XVG and eXVG are that the eXVG has:

• larger inlet and outlet plates to accept 2.0 inch flanges (rather than 1.5 inch flanges with the XVG)

• contoured inlet

• larger output port

Both the XVG and eXVG are available in Main valve and Pilot valve form. A Pilot-type XVG, for instance, is the same as the Main-type XVG, with the exception that a larger flow body is used. This reduces the flow area of the Pilot valve to approximately 60% of the flow area of the corresponding Main valve. The result is that a Pilot valve will have finer resolution but will only support lower flow levels than the corresponding Main valve. See Section 3.1 for additional details.

The part number extension used to describe a valve indicates the model and the type of the valve. See Table 2-2.

Part # Extension

Model Type

-001 XVG Main, RS232

-002 XVG Pilot, RS232

-003 eXVG Main, RS232

-004 eXVG Pilot, RS232

-005 / -009 XVG Main, RS485

-006 / -010 XVG Pilot, RS485

-007 / -011 eXVG Main, RS485

-008 / -012 eXVG Pilot, RS485

Table 2-2. Model Numbers and Types

Product Definition Numbers The Product Definition Number (PDN) numbering system defines the specific XVG/eXVG setup and configuration. See Figure 2-3 for an example of a PDN and its parameters.

The PDN is identified on the nameplate, as shown in Figures 2-7 through 2-10 at the end of this section.


The PDN and its associated parameters and values must be defined and referenced in the procurement process of this product. Contact Precision Engine Controls Corporation for assistance in defining this number and it’s associated parameters and values for your application.

Figure 2-3. Product Definition Number Details (sample)

Operation Mode (MODE)

The XVG/eXVG can operate in four different modes, as described in Table 2-3. The 5002800, the basic version of the XVG/eXVG, can only operate in Stroke mode. The 5002801 can operate in all 4 modes.

See Sections 2.3 and 3.2 of this manual for additional information about operation modes of the XVG/eXVG.

# Operation Mode

Description

0 Stroke Valve position (stroke) is a direct function of command value

1 Flow Measurement

Valve position (stroke) is a direct function of command value. Measured flow is provided as an analog output signal, typically on AOCH1.

2 Flow Control Command signal specifies requested flow in PPH. Valve automatically adjusts metering of the flow tube assembly to achieve flow as defined by the command signal and scaled by the Max Flow parameter of the PDN.

3 Flow Limiting Command signal specifies requested flow in PPH based on a schedule of max/min flow values at a number of outlet pressure values. Valve automatically positions metering flow tube to achieve flow as defined by the command signal and interpolated from the flow schedule.

Table 2-3. Operation Mode Configuration

Command Signal (CMD)

The Command Signal parameter in the PDN describes the signal format and range of the fuel Demand signal used to control the XVG/eXVG. See Table 2-4 for details.


# Command

Signal Description

0 4 to 20 mA 4 mA = 0% command 20 mA = 100% command

1 0 to 5 VDC 0 VDC = 0% command 5 VDC = 100% command

2 1 to 5VDC 1 VDC = 0% command 5 VDC = 100% command

Table 2-4. Command (AICH0) Signal Configuration

Analog Output Channels (AOCH0 & AOCH1)

Analog output channels 0 and 1 (AOCH0 and AOCH1) are feedback signals. Two digits in the PDN describe each channel. The first digit represents the parameter represented by the feedback signal on that channel. See Table 2-5.

The second digit represents the signal configuration, both format and range, for the feedback signal on that channel. See Table 2-6.

The PDN shown in Figure 2-2, for example, has the two digits “12” for AOCH0. This means that the feedback signal on Channel 0 represents the valve position and the signal is in Volts, with a range of 1 to 5VDC.


# Analog Output

Parameter Description

0 Disabled The analog output channel is disabled.

1 Valve Position Output is scaled to report valve position. The output tracks Demand under normal operation in Stroke and Flow Measurement modes.

2 Measured Flow

Output is scaled to report measured flow:

Minimum = 0 pounds per hour (PPH)

Maximum = Max value specified in Maximum Flow Parameter

3 N/A Not applicable

4 Input Pressure

(psig)

Output is scaled as a function of measured input pressure:

Minimum = 0 psig

Maximum = 500 psig

5 Output Pressure

(psig)

Output is scaled as a function of measured output pressure:

Minimum = 0 psig

Maximum = 500 psig

6 Gas Temp

(Celsius)

Output is scaled as a function of gas temp:

Minimum = 0 °C

Maximum = 150 °C

Table 2-5. Analog Output Parameter Channel Configuration

# Analog Output Signal

Configuration Description

0 4 to 20 mA 4 mA = 0% 20 mA = 100%

1 0 to 5 VDC 0 VDC = 0% 5 VDC = 100%

2 1 to 5VDC 1 VDC = 0% 5 VDC = 100%

3 0 to –5VDC 0 VDC = 0% –5 VDC = 100%

Table 2-6. Analog Output Signal Configuration


Gas Constants (R & k)

The R parameter in the PDN represents the gas constant R for the gas being regulated by the XVG/eXVG. The k parameter in the PDN represents the specific heat ratio for the gas being regulated by the XVG/eXVG.

These fuel properties vary for different gases. Flow measurement accuracy is based on accurate correlation of these properties with the media being measured. The Gas Constant numbers for R and k must correlate with the gas being regulated by the XVG/eXVG. The gas to be regulated must be defined in the procurement process for this product to ensure that the proper values for the constants are used. See Table 2-7.

Gas Constant Description

R

(ft-lbf / lbm-°R)

Gas Constant

Air = 53.34

Natural Gas = 79.1

Propane = 35.04

k Specific Heat Ratio Cp/Cv

Air = 1.4

Natural Gas = 1.273

Propane = 1.12

Table 2-7. Gas Constants Configuration

Maximum Flow (MAX FLW)

The MAX FLW parameter is used to scale the analog output channel. It is not the maximum flow capability of the XVG/eXVG. Maximum flow capability is a function of gas pressure and temperature conditions. Operating conditions must be carefully considered when choosing the maximum flow value for an application. See Table 2-8.


Maximum Flow Description

PPH X 1000 Units are kPPH. This parameter scales the analog output when configured for measured flow.

Table 2-8. Max Flow Configuration

Calibration Curve (CAL CURVE)

Performance goals for flow and pressure for a given application are used to empirically determine the stroke and nominal flow area (CdA) needed at various points across the Demand signal range. The stroke values, and their corresponding flow area values, are plotted relative to Demand signal percentages (10%, 25%, 50%, 75%, and 100%, for instance) to define performance curves. Precision Engine Controls Corporation determines which calibration curve is necessary to achieve the customer’s desired performance profile across the Demand signal range. The Calibration Curve field in the PDN is used to identify the curve number that has been used to calibrate the unit. See Table 2-9.

Field Description

Calibration Curve Desired fuel flow and/or stroke vs. command characteristic for valve. Contact Precision Engine Controls Corporation for available flow characteristics.

Table 2-9. Calibration Curve

Electrical Interface (ELECT)

The Electrical Interface parameter specifies which one of the three electrical interface options has been used. See Table 2-10.


# Electrical Interface

Description

0 Terminal Block Only

Power and signal interfaces directly to the on-board terminal block.

1 13-Wire, EP Harness

A thirteen-wire, explosion proof, pigtail harness is installed with the valve.

2 15-Wire, EP Harness

A fifteen-wire, explosion proof, pigtail harness is installed with the valve.

Table 2-10. Electrical Interface

Note. Hazardous Location Requirement: In order to comply with ATEX requirements, the user must install an explosion-proof seal within 18 inches of the valve enclosure exit when interfacing directly to the terminal block.

Flange Accessory (FLANGE)

The Flange Accessory parameter specifies which one of the three flange accessory options has been used. See Table 2-11.

# Flange

Accessory Description

0 None No adapters installed

1 MS Adapter Kit MS33786-20 Flange, (4-Bolt) (XVG Only)

2 ANSI 1.5in. SAE J518-24 TO ANSI #150 Flange (XVG Only)

Table 2-11. Flange Interface


Note. Contact Precision Engine Controls Corporation for details on flange conversions.

2.3 Operating Modes of XVG/eXVG The XVG/eXVG is available in four fully programmable operating modes. The basic XVG/eXVG is configured to operate in stroke mode. Flow measurement, flow control and flow-limiting modes are available as optional configurations.

Stroke Mode In stroke mode, the XVG/eXVG tracks the fuel Demand signal in proportion to the flow tube assembly position. As Demand increases, the solenoid exerts more force on the flow tube assembly, thus stroking open the valve until it reaches the appropriate position while further compressing the return spring. As Demand decreases, the solenoid exerts less force on the flow tube assembly, thus allowing the return spring to stroke closed the valve until it reaches the appropriate position. Positioning feedback from an LVDT is sent to a control loop to help control the flow tube assembly position.

Flow is metered between the flow tube and orifice in proportion to flow tube position and the corresponding flow area (CdA). The flow area ranges from zero at 0% to maximum at 100%.

Flow Measurement Mode The flow measurement mode option includes two gas pressure sensors and a gas temperature sensor.

In flow measurement mode, the valve tracks the fuel Demand signal as outlined in the stroke mode. The mass flow is determined using the valve effective flow area, pressure and temperature sensor information, and the gas constants described in the PDN.

An analog feedback signal that is proportional to measured mass flow is typically provided on an analog output. The minimum feedback signal represents zero flow. The maximum feedback signal represents maximum mass flow. This feedback signal is scaled by the MAX FLW parameter in the PDN. Mass flow may differ from Demand depending on flow conditions.

Flow Control Mode In flow control mode, the valve tracks the fuel Demand signal in proportion to measured mass flow.

An analog feedback signal that is proportional to measured mass flow is typically provided on an analog output. The minimum feedback signal


represents zero flow. The maximum feedback signal represents maximum mass flow. This feedback signal is scaled by the MAX FLW parameter in the PDN.

Note. Flow Control Mode will not initiate until a positive 20 psid (inlet greater than outlet) is measured across the valve.

As fuel Demand increases or decreases the controls energize the solenoid coil to the appropriate level and the flow tube strokes open or closed until the measured mass flow equals the commanded mass flow. As fuel Demand, pressure or temperature change, a control loop adjusts the flow tube position to establish the requested mass flow.

Flow Limiting Mode The optional flow-limiting mode prevents over- or under-fueling of an engine. Pre-programmed schedules for maximum and minimum fuel mass flow relative to output pressure are used to determine how the fuel Demand signal is to be tracked.

As fuel Demand increases or decreases the control electronics read the outlet pressure and scale mass flow according to the Demand signal level and fuel limit schedules. The flow tube assembly position is controlled to establish the requested limit for mass flow.

Analog feedback is in terms of measured mass flow. Minimum feedback is zero flow. Maximum feedback is the preprogrammed maximum mass flow.

2.4 Mechanical Functional Description See Figure 2-4 for a view of the assemblies described below.

Housing Assembly The housing assembly is a two-piece unit that consists of a machined valve body and an electronics enclosure. The enclosure attaches to the valve body with four attachment screws.

A breather is incorporated into the housing assembly in order to vent any pressure build-up within the entire assembly. If any dynamic seal leaks occur, the resultant gas build-up will vent to ambient beginning at 1 or 2 psig. See Figure 2-5.

Solenoid Motor Assembly

The solenoid motor assembly consists of a flow tube and armature assembly, coil, housing and damping system. This electro-magnetic assembly contains the only moving part within the valve assembly.


Fuel flow is regulated by changing the position of the flow tube assembly.

Inlet Plate Assembly The inlet plate assembly consists of a machined plate containing a linear variable differential transformer (LVDT), dynamic seal, scraper, temperature sensor, and optional pressure sensor.

The scraper is designed to scrape contaminants from the flow tube. (See Figure 2-2) An o-ring seal prevents water intrusion. An SAE J518 –24 (1.50 inch), Code 61 pipe interface is machined into the inlet plate for the XVG. An SAE J518 -32 (2.0 inch), code 61 pipe interface is machined into the outlet plate for the eXVG. Other pipe interfaces are optional.

Outlet Plate Assembly The outlet plate assembly is a machined plate containing a dynamic seal and an optional outlet pressure sensor.

The plate is o-ring sealed to prevent water intrusion. An SAE J518 –24 (1.50 inch), Code 61 pipe interface is machined into the outlet plate for the XVG. An SAE J518 -32 (2.0 inch), code 61 pipe interface is machined into the outlet plate for the eXVG. Other pipe interfaces are optional as attachments.

Orifice Plate The orifice plate is a machined assembly containing an orifice seal and flow divider. The orifice seal prevents flow leakage into the outlet.

Cover The cover is a machined, o-ring sealed plate that allows access to the electronics terminal blocks.


Figure 2-4. Exploded View of the XVG/eXVG

Figure 2-5. Partial Cutaway View of Breather Vent


2.5 Electrical Functional Description The XVG/eXVG contains an on-board, digitally controlled electronic assembly. The assembly contains analog-to-digital (A/D) converters, a digital signal processor (DSP), power supplies, and system isolation and conditioning circuits. Figure 2-6 shows a block diagram of the electronic system.

Control Electronics The control electronics assembly contains two electronic assemblies. The control electronics are located within the housing assembly and are accessible via the cover.

The control electronics assembly internally interfaces with the motor and LVDT along with temperature sensors and optional pressure sensors. External interfaces include analog, discrete and serial data. A digital signal processor (DSP) controls all valve functions.

The control electronics interfaces with the engine control system and power supply. The assembly incorporates analog and discrete inputs and outputs, and a serial interface. It also provides signal conditioning for all internal analog and discrete I/O, as well as LVDT and sensor inputs.

The digital signal processor (DSP) provides main control functions. All serial communication, PID control, health monitoring, A/D conversion and solenoid motor control is handled within the processor. An external watchdog IC is used to monitor the DSP. This IC also monitors the supply voltage to the DSP and will independently shut down the valve to close position in case of DSP catastrophic failure, low voltage, brownout condition, firmware problems and system hang conditions.

The DSP converts analog inputs to digital counts for use in the control functions. The analog outputs are converted from digital counts and output to the user.

A 10 kHz excitation signal is generated within the DSP to drive the LVDT. The LVDT output is signal conditioned and converted for digital position measurement.

A control signal is sent to the solenoid drive circuit. Solenoid motor current is varied to control flow tube movement. Solenoid motor current feedback is provided to the DSP through isolation circuits.

Signals from temperature sensors and optional pressure sensors are converted to digital counts and used in the control functions.


Figure 2-6. XVG/eXVG Electronics System Block Diagram

Power The XVG/eXVG operates on nominal 24 VDC input power. Two 24 VDC inputs are required. The electronics input provides power to the control electronics. The solenoid input provides power to the solenoid. Both power inputs are required for system functionality.

The control electronics internal power supply isolates and conditions the 24 VDC input and converts it into 3.3 VDC, +15 VDC and –15 VDC. The internal power supply filters and protects against noise transients and reverse voltage. The internal power supply is isolated from the solenoid power.

Analog Inputs/Outputs The XVG/eXVG receives analog inputs from an external, user-provided controller and also provides analog outputs. The XVG/eXVG includes a single analog input that is dedicated for the fuel Demand control signal. The base XVG/eXVG (p/n 5002800-xxx) provides a single analog output for feedback. The XVG/eXVG option with pressure sensors (p/n 5002801-xxx) provides two analog outputs for feedback. Refer to Section 1: Installing the XVG/eXVG, for typical connections. Contact Precision


Engine Controls Corporation regarding applications that require additional analog input and output.

The analog input can be configured to operate with any of three different signal formats or ranges, as described in Table 2-4. The two analog output channels can be configured independently to operate with any of four different signal formats, ranges or polarities as described in Table 2-6. Refer to Section 1.2: General Specification Summary, for load values.

Analog Input Channel 0 (AICH0) is configured for the fuel Demand signal. Analog Output Channel 0 (AOCH0) is typically configured for the valve position feedback signal. Analog Output Channel 1 (AOCH1) is typically configured for the flow measurement feedback signal. See Section 2.2: Versions of the XVG/eXVG (PDN) for a description of how the valve can be configured.

Discrete Inputs/Outputs Discrete Input Channel 0 (DICH0) is not currently implemented. Discrete Output Channel 0 (DOCH0) is the Fault alarm which is configured as “Trip to Open” on a fault condition. These discrete interfaces are optically isolated. Refer to Section 1: Installing the XVG/eXVG, for a typical connection.

Serial Interface The XVG/eXVG contains a single, optically isolated RS232 or RS485 (optional) serial communication interface. The serial interface communicates set-up parameters, performance conditions and fault diagnostics. Refer to Section 1: Installing the XVG/eXVG, for a typical connection.

2.6 Identification Plate A product identification plate is attached to the XVG/eXVG housing assembly. See Figures 2-7 through 2-10 for typical identification plates used with the different versions of the XVG/eXVG.

The identification plate lists model designation, product part number, revision and unit serial number. Hazardous area operation, certification and electrical wiring interface information is also provided.


Figure 2-7. Typical Identification Plate for XVG, p/n 5002800-001 or -002

Figure 2-8. Typical Identification Plate for eXVG, p/n 5002800-003 or -004


Figure 2-9. Typical Identification Plate for XVG, p/n 5002801-001 or -002

Figure 2-10. Typical Identification Plate for eXVG, p/n 5002801-003 or -004



INTENTIONALLY BLANK

3 OPERATING THE XVG/eXVG

3.1 Performance Factors The following factors are used to describe, affect, or achieve the desired performance for the XVG/eXVG.

Demand Signal The analog input signal (AICH0) is the only signal used to control the performance of the XVG/eXVG. It is also referred to as the fuel Demand signal. The XVG/eXVG can be configured to accept one of three different command signal formats, as described in Table 3-1 below. The command signal format used for a unit is described in its PDN, as described in Section 2.2 of this manual.

Command Signal

Description

4 to 20 mA 4 mA = 0% command 20 mA = 100% command

0 to 5 VDC 0 VDC = 0% command 5 VDC = 100% command

1 to 5VDC 1 VDC = 0% command 5 VDC = 100% command

Table 3-1. Command (AICH0) Signal Configurations

Command signal levels are often referred to as percentages of their ranges rather than as absolute values. Table 3-2 lists percentage values for the three command signal formats supported by the XVG/eXVG.

CH. 3: OPERATING THE XVG/eXVG 47

% of Range

4 to 20 mA 0 to 5 V 1 to 5 V

0% 4 mA 0 V 1.0 V

10% 5.6 mA 0.5 V 1.4 V

20% 7.2 mA 1.0 V 1.8 V

30% 8.8 mA 1.5 V 2.2 V

40% 10.4 mA 2.0 V 2.6 V

50% 12 mA 2.5 V 3.0 V

60% 13.6 mA 3.0 V 3.4 V

70% 15.2 mA 3.5 V 3.8 V

80% 16.8 mA 4.0 V 4.2 V

90% 18.4 mA 4.5 V 4.6 V

100% 20 mA 5.0 V 5.0 V

Table 3-2. Command Signal Percentage Values

What the command signal is actually controlling depends on the operating mode for which the XVG/eXVG is configured.

Feedback Signal The analog output signal (AOCH0) is used to monitor the performance of the XVG/eXVG. It is also referred to as the Feedback signal. Upon installation, it is important to ensure 24 VDC is applied to the XVG/eXVG before gas pressure is supplied otherwise factory calibration could be affected. This is because the zero position of the Feedback signal is calibrated each time power is supplied or a software reset is performed.

Note. Ensure 24 VDC is applied before gas pressure to prevent changing the factory calibration.

Flow Area The only moving part in the XVG/eXVG is the flow tube assembly. The position and movement of the flow tube assembly are referred to as the stroke of the valve. The XVG/eXVG has a maximum stroke of 0.250in.

The position of the flow tube assembly determines the actual amount of area through which the fuel can flow. When the position is at 0.0in., the flow area is zero because the valve is closed and no gas can flow. When


the position is at its maximum value of 0.250in., the valve is fully open and the flow area is at its maximum.

The maximum flow area for the XVG/eXVG is an indication of its fuel-flow capacity. Table 3-3 lists the maximum flow area for each version of the XVG/eXVG.

Version of Valve Maximum Flow Area (in2)CdA (sonic)

XVG – Main 0.49

XVG – Pilot 0.32

eXVG – Main 0.60

eXVG – Pilot 0.32

Table 3-3. Maximum Flow Area for XVG/eXVG

Calibration Curves Performance goals for flow and pressure for a given application are used to empirically determine the stroke and nominal flow area (CdA) needed at various points across the Demand signal range. The stroke values, and their corresponding flow area values, are plotted relative to Demand signal percentages (10%, 25%, 50%, 75%, and 100%, for instance) to define performance curves.

While the XVG/eXVG has a full-range stroke capability of 0 to 0.250 inches, some applications may only require that a portion of this range, such as 0 to 0.130 inches, be used.

Other parameters that are used in defining calibration curves may include minimum and maximum values for inlet pressure, outlet pressure, flow rate, and feedback percentage.

Precision Engine Controls Corporation determines the proper calibration curve, and other parameters, necessary to achieve the customer’s desired performance profile across the Demand signal range for a particular application. A calibration curve is used for every XVG/eXVG and is incorporated into the PDN (see Section 2.2 for details).

3.2 Operating Modes

The XVG/eXVG has four operating modes:

• Stroke

• Flow Measurement

• Flow Control

• Flow Limiting


The operating mode of a XVG/eXVG determines how commands are processed.

Stroke Mode In Stroke Mode, the Demand signal directly controls the position of the flow tube assembly. The LVDT provides precise feedback about the flow tube position to the electronics of the XVG/eXVG, thus allowing the stroke to accurately track the Demand signal.

Demand Signal

A Demand signal of 0% will move the flow tube assembly to the minimum position, which results in a closed valve.

A Demand signal of 100% will move the flow tube assembly to the maximum position of its range, as determined by the calibration curve for the unit.

The calibration curve determines the flow tube position for Demand signal levels between 0% and 100%. See Figure 3-1 for a representation of Stroke vs. Demand signal performance.

Figure 3-1. Stroke vs. Fuel Demand Curve


Flow Measurement Mode A XVG/eXVG in Flow Measurement mode processes commands in the same manner as a XVG/eXVG in Stroke mode. The Demand signal directly controls the position of the flow tube assembly. The LVDT provides precise feedback about the flow tube position to the electronics of the XVG/eXVG, thus allowing the stroke to accurately track the Demand signal.

Pressure sensors at the input and output ports, in conjunction with the temperature sensor, provide the means to measure flow rate. The XVG/eXVG uses pressure and temperature information from the sensors, in conjunction with the gas constants defined in the PDN, to calculate the flow rate.

Demand Signal

A Demand signal of 0% will move the flow tube assembly to the minimum position, which results in a closed valve.

A Demand signal of 100% will move the flow tube assembly to the maximum position of its range, as determined by the calibration curve for the unit.

The calibration curve determines the flow tube position for Demand signal levels between 0% and 100%. See Figure 3-1 for a representation of Stroke vs. Demand signal performance.

Flow Control Mode The Demand signal controls the flow rate for XVG/eXVG units in Flow Control mode. XVG/eXVG units in Flow Control mode include the same pressure and temperature sensors described in Flow Measurement mode, allowing for continual flow-rate detection.

When the Demand signal changes, the XVG/eXVG compares the commanded flow rate to the measured flow rate. The difference between the commanded and measured flow rates, known as the flow error, is used to determine the position set point. The XVG/eXVG initiates a stroke to move the flow tube assembly to the new position, which will in turn have a flow rate closer to the commanded flow rate. If any flow error is detected after the move, the XVG/eXVG will change the position set point again, causing another position adjustment. The XVG/eXVG will continue adjusting the flow tube assembly position until the measured flow rate matches the commanded flow.


Demand Signal

A Demand signal of 0% will set the flow rate at 0 kPPH, resulting in the valve closing.

A Demand signal of 100% will set the flow rate to the unit’s maximum flow rate, depending on pressure and temperature conditions.

The calibration curve used for a XVG/eXVG unit in Flow Control mode is a linear stroke for Demand signal levels between 0% and 100%.

See Figure 3-2 for a representation of Flow Rate vs. Demand signal performance.

Figure 3-2. Flow Rate vs. Fuel Demand Curve

Flow Limiting Mode The Demand signal also controls the flow rate for XVG/eXVG units in Flow Limiting mode. XVG/eXVG units in Flow Limiting mode include the same pressure and temperature sensors described in Flow Measurement mode, allowing for continual flow-rate detection.

Flow Limiting mode requires that the maximum and minimum flow rates be pre-defined for a range of outlet pressures. The XVG/eXVG uses this information to associate a specific range of allowable flow rates with each outlet pressure in the defined range. The Demand signal level and the outlet pressure determine the commanded flow rate.


When the Demand signal changes, the XVG/eXVG uses the outlet pressure to determine the flow-rate that corresponds to the new Demand signal under the existing conditions. The XVG/eXVG compares the commanded flow rate to the measured flow rate. The difference between the commanded and measured flow rates, known as the flow error, is used to determine the position set point. The XVG/eXVG initiates a stroke to move the flow tube assembly to the new position, which will in turn have a flow rate closer to the commanded flow rate. If any flow error is detected after the move, the XVG/eXVG will change the position set point again, causing another position adjustment. The XVG/eXVG will continue adjusting the flow tube assembly position until the measured flow rate matches the commanded flow.

Demand Signal

At a given outlet pressure, a Demand signal of 0% will set the flow rate to the minimum flow rate defined for that outlet pressure based on the calibration curve information.

At a given outlet pressure, a Demand signal of 100% will set the flow rate to the maximum flow rate defined for that outlet pressure based on the flow-limiting curve information.

Flow rates for Demand signal levels between 0% and 100% are linearly interpolated between the minimum and maximum defined flow rates for that outlet pressure.

Maximum flow rates for outlet pressures that have not been explicitly defined are linearly interpolated between maximum flow rates for the closest outlet pressures that have been defined.

Minimum flow rates for outlet pressures that have not been explicitly defined are linearly interpolated between minimum flow rates for the closest outlet pressures that have been defined.

The pre-defined maximum and minimum flow rate vs. outlet pressure information is part of the calibration information for a XVG/eXVG unit in Flow Limiting mode. PECC determines the proper calibration curve to use for each application based upon the customer’s desired flow rate characteristics. Contact PECC for details.

See Figure 3-3 for a representation of Flow Rate vs. Outlet Pressure curves that are used in Flow Limiting mode.

3.3 Feedback The XVG/eXVG offers either one or two analog output channels, depending on the configuration. Units with the base part number “5002800” have one analog output channel, AOCH0. Units with the base part number “5002801” have two analog output channels, AOCH0 and AOCH1. Each of the analog output channels on the XVG/eXVG can be


configured independently to use one of four different feedback signal formats, as described in Table 3-4. The feedback signal format used for each analog output of a unit is described in its PDN, as described in Section 2.2 of this manual.

Figure 3-3. Flow Rate vs. Outlet Pressure Curve (example)

Command Signal

Description

4 to 20 mA 4 mA = 0% 20 mA = 100%

0 to 5 VDC 0 VDC = 0% 5 VDC = 100%

1 to 5VDC 1 VDC = 0% 5 VDC = 100%

0 to – 5VDC 0 VDC = 0% – 5 VDC = 100%

Table 3-4. Feedback (AOCH0 or AOCH1) Signal Configurations


The analog outputs can also be configured to provide feedback for five different parameters. See Table 3-5 for a description of these parameters.

Units with the base part number “5002800” do not have pressure sensors, so they can only provide feedback for Stroke or Gas Temperature. Units with the base part number “5002801” have pressure sensors, so they can provide feedback for any of the five parameters shown in Table 3-5.

Analog output AOCH0 is typically configured for Stroke feedback. Analog output AOCH1 is typically configured for Flow Measurement feedback. (AOCH1 is disabled on units with the base part number “5002800”.) The analog outputs can be configured for any of the five parameters shown in Table 3-5, but deviations from the typical analog output configuration must be indicated in the PDN when the unit is being ordered.

Analog Output

Parameter

DESCRIPTION

Stroke

Output is scaled to report the flow tube assembly position. Output tracks Demand signal under normal operation in Stroke Mode and Flow Measurement Mode.

Measured Flow

(kPPH)

Output is scaled to report measured flow:

Minimum = 0 PPH

Maximum = Max. value specified in Maximum Flow Parameter in PDN

Input Pressure

(psig)

Output is scaled as a function of measured input pressure:

Minimum = 0 psig

Maximum = 500 psig

Output Pressure

(psig)

Output is scaled as a function of measured output pressure:

Minimum = 0 psig

Maximum = 500 psig

Gas Temp

(Celsius)

Output is scaled as a function of gas temp output pressure:

Minimum = 0 °C

Maximum = 150 °C

Table 3-5. Feedback Parameter Configuration

3.4 Monitoring System Health The firmware program continuously monitors system health while the XVG/eXVG is powered. If any of the critical health parameters are out of the normal operating range, the XVG/eXVG electronics shut down the


unit and output a discrete FAULT alarm to the user’s controller. The XVG/eXVG firmware also captures the fault data in an EEPROM.

FAULT Alarm The FAULT alarm is a non-latching, solid-state contact from the XVG/eXVG. Upon power-up, the FAULT circuit closes and stays CLOSED in the normal operating condition. When the XVG/eXVG detects a system fault, it opens the FAULT circuit.

If a critical system fault is detected the XVG/eXVG will enter a shutdown state immediately. Non-critical faults will trigger the FAULT alarm as a warning, but they will not cause a shutdown. See Table 5-4 of this manual for a list of faults, possible causes, and the action taken when the fault is detected (shutdown or warning).

A fault file can be uploaded from the XVG/eXVG using PECC’s proprietary XView software via the RS232 or RS485 (optional) interface. See Section 5.2. The fault file will provide fault information and possible causes. Contact Precision Engine Controls Corporation to request this software.

Shutdown State The Shutdown State is a safety condition that will prevent uncontrolled operation of the valve. In a shutdown state the Pulse Width Modulator (PWM) output from the DSP is removed so the valve will close and not respond to command. The XVG/eXVG will not respond to the Demand signal until the faulting condition is removed.

If the faulting condition is not known, try cycling power OFF then ON. If the problem that caused the shutdown is no longer present, the XVG/eXVG will return to a normal operating state. If the problem is still present, the XVG/eXVG will resume a shutdown state. It is important to retrieve the fault file from the XVG/eXVG in either situation to determine the nature of the fault and possible causes. See Section 5.2 of this manual for details about how to upload the fault file from the XVG/eXVG.

Note: The only way to exit the Shutdown State is to first remove the condition that caused it. Once the faulting condition is removed, the XVG/eXVG will function normally.



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4 MAINTAINING THE XVG/eXVG

The XVG/eXVG is designed for long, reliable life. Some regular minor maintenance can extend the service life of the equipment and prevent serious problems from occurring

Preventative maintenance actions, such as normal, routine inspection and cleaning instructions, are described in the Section 4.1 below. Perform recommended maintenance periodically and in parallel with normal engine maintenance schedules. No additional engine downtime should be expected.

Corrective maintenance actions, those minor repairs that can be performed in the field in the unlikely event that the XVG/eXVG malfunctions, are described in Section 4.2. These are the only repairs that can be performed by the customer.

If corrective maintenance does not fix any malfunction, the valve must be sent to Precision Engine Controls Corporation for repair or replacement. Contact Precision Engine Controls Corporation for Return Material Authorization (RMA) before shipping the valve back to the factory.

Note. Keep a maintenance log for the XVG/eXVG fuel-metering valve. A service history makes it easier to establish a maintenance schedule.

4.1 Preventive Maintenance

This section contains information and instructions for routine maintenance. By performing these procedures at regular intervals you can extend the service life of the equipment and prevent serious problems from occurring.

Visual Inspection Perform the following visual examination every week.

• Inspect the valve exterior for loose or broken parts. Pay particular attention to wires, shields and connectors.

• Thoroughly inspect wires and cables for wear, fraying, or damage. Repair any damaged areas you may find.

• Check fuel lines and fittings for leaks or damage.


External Cleaning Clean the valve exterior every 60 to 90 days, or more often, as the environment dictates. This cleaning aids the visual inspection and prevents unwanted dirt build-up.

Be sure to depressurize the fuel system before cleaning the valve.

The XVG/eXVG can be externally cleaned with a jet of water. The XVG/eXVG enclosure is environmentally rated to NEMA 4 and European IP56. As such, the XVG/eXVG can withstand a strong water jet directed at its enclosure with no harmful effects. The test conditions necessary to secure the environmental rating involved a jet nozzle with an inside diameter of 12.5-mm splashing a volume of 100 liters per minute from a distance of 2.5-3 meters from all sides of the enclosure for duration of 3 minutes.

Precision Engine Controls Corporation recommends that the flow rate of the water jet used in the cleaning, as well as the duration of the cleaning, not exceed the flow rate and duration used in the environmental rating test.

Note. Minimize exposure to water during routine maintenance.

WARNING - Explosion Hazard

Serious injury may result if cleaning is performed while valve is pressurized. Depressurize fuel system prior to valve cleaning.

The following procedure is an alternate method of cleaning the XVG/eXVG.

• Depressurize the fuel system prior to cleaning the valve.

• Remove loose dirt with low pressure, clean dry air.

• Carefully wipe exterior surfaces with clean cloth and either mild soap and water or ethyl alcohol.

Fuel Filter Replacement Use of recommended fuel filters helps prolong equipment service life. Therefore, be sure to replace fuel filters at least every six-(6) months.

CH. 4: MAINTAINING THE XVG/eXVG 59

4.2 Corrective Maintenance

This section describes corrective maintenance allowable in the field. Refer to Section 5: Troubleshooting, for more information.

Required Items Corrective maintenance actions require the following items:

• Precision Engine Controls Corporation special tool; P/N 5003760-001 for the XVG or P/N 5003948-001 for the eXVG

• Orifice seal replacement kit; P/N 5003261-001 or -002 (XVG only)

• O-ring; P/N M83248/1-034 (XVG), P/N M83248/2-037 (eXVG),

• O-ring lubricant, such as Parker O-Lube

• Solvents for cleaning (see below for recommended solvents)

Recommended Solvents

Chlorinated solvents such as ethylene dichloride, Freon or similar chemicals are excellent for dissolving petroleum-based contaminants such as tar, paraffin and other hydrocarbons. Denatured alcohol may also be used, but it will not be as effective as the chlorinated solvents.

Certain ketone solvents, such as Acetone and MEK (Methyl-Ethyl Ketone), can damage the Viton® o-ring seals contained within the valve. If a ketone is used as a cleaning agent, make sure to limit the exposure time to no more than five minutes. Use shop air to ensure all residual solvent has evaporated.

Orifice Cleaning

WARNING - Explosion Hazards

This procedure involves handling explosive mixtures. Ensure venting is adequate and fuel is diluted in order to prevent explosion.

Serious injury may result if cleaning is performed while valve is pressurized. Depressurize fuel system prior to valve cleaning.


WARNING - Health Hazard

Use Latex or other appropriate hand protection when cleaning or disassembling valve.

The XVG/eXVG can be cleaned while it is on the engine, as long as the valve OUTLET is accessible.

Procedure 4.2.1

To clean the orifice, follow these steps:

a) Depressurize the fuel system.

b) Secure the fuel system.

c) Remove the engine igniter circuit breaker.

d) Remove the valve OUTLET fuel line.

e) Remove 24VDC

f) Remove the orifice plate using Precision Engine Controls Corporation special tool; P/N 5002994-001 for the XVG or P/N 5003948-001 for the eXVG, as shown in Figure 4-1 or Figure 4-2, respectively.

g) Remove the orifice o-ring seal.

Note. Remove the orifice slowly to ensure the orifice seal and o-rings are not damaged. Contact Precision Engine Controls Corporation for special tool P/N 5002994-001 for the XVG or P/N 5003948-001 for the eXVG to assist with this step. or P/N 5003948-001 for the eXVG to assist with this step.


Figure 4-1. XVG Orifice Plate Removal

Figure 4-2. eXVG Orifice Plate Removal


h) Clean away dirt and contaminants using the solvents recommended at the beginning of Section 4.2. Ensure that the orifice plate is clean and dry. See Figure 4-3 for a photo of the XVG orifice plate. See Figure 4-4 for a photo of the eXVG orifice plate

i) Inspect the orifice seal and o-ring for nicks, scrapes and damage. If the orifice seal is damaged, contact Precision Engine Controls Corporation for the orifice seal replacement kit; P/N 5003261-001 or -002. If the o-ring seal only is damaged, contact Precision Engine Controls Corporation for o-ring; P/N M83248/1-034 (XVG).or P/N M83248/2-037 (eXVG).

j) Install the o-ring seal. Lubricate, as necessary, using an o-ring lubricant, such as Parker O-Lube.

k) Install the orifice plate slowly using Precision Engine Controls Corporation special tool; P/N 5002994-001 for the XVG or P/N 5003948-001 for the eXVG.

l) Torque the orifice plate to 8 to 10 ft-lbs.

m) Reconnect the OUTLET fuel line. Torque the flange bolts to 550-700 in-lb.


Figure 4-3. XVG Orifice Plate

Figure 4-4. eXVG Orifice Plate



Flow Tube Cleaning To clean the flow tube, follow these steps:

WARNING

Do NOT score the outer diameter of the flow tube. This could cause an external fuel leak.

Procedure 4.2.2

a) Perform steps a) through h) of Procedure 4.2.1.

b) Using a soft bristle brush and solvents recommended at the beginning of Section 4.2, gently clean the inside of the flow tube. Clean any visible contaminants on the visible outer diameter.

c) Dry the tube inside of the flow tube using a soft towel or shop air.

d) Repeat steps 4.2.1 h) through m).

4.3 Calibration Re-calibration in the field is not generally recommended or feasible because flow calibration procedures require special equipment not normally available in the field. Return the XVG/eXVG to the factory for re-calibration if adjustments are necessary. Contact Precision Engine Controls Corporation for Return Material Authorization (RMA) before shipping the valve back to the factory.

4.4 Refurbishment

Contact PECC for details about refurbishment options for the XVG/eXVG.

5 TROUBLESHOOTING THE XVG/eXVG

This section aids maintenance technicians in troubleshooting and isolating malfunctions in the XVG/eXVG. You can isolate most faults by using the XView Communications Software. Refer to the software user manual for fault monitoring and uploading instructions. (Contact PECC regarding the XView User Manual.)

The XVG/eXVG contains highly reliable components and is thoroughly tested prior to delivery. However, failures may develop over periods of continuous service. Personnel performing fault analysis should be thoroughly acquainted with the physical and electrical configurations as described in Section 2: Understanding the XVG/eXVG and Section 3: Operating the XVG/eXVG of this manual.

Resolve problems noted during operation or maintenance as soon as possible. The cause of many problems can often be traced by using the block diagram shown in Section 2.

WARNING

Operating the valve while it is in a malfunctioning condition may cause serious injury or equipment damage.

5.1 Electrical Troubleshooting

If an electrical circuit failure is suspected, measure the interface circuit impedance to determine which circuits (if any) have failed. Table 5-1 lists expected circuit impedance values with no power connected to the valve. If the impedance is not within the expected range, the most likely cause is a damaged valve circuit. In such a case, return the valve to Precision Engine Controls Corporation for repair or replacement. Contact Precision Engine Controls Corporation for Return Material Authorization (RMA) before shipping the valve back to the factory.

Table 5-2 lists the common failures that can be expected when the valve is first installed. These failures are usually caused by wiring or power supply problems.


Table 5-3 lists some common failures that can be expected after equipment has been installed. These failures are usually due to power supply problems or failures within the valve. Use the XView Communications software to determine if there are any failures inside the valve. Refer to Section 5.3 for information regarding these faults.

Function Wire Color Terminal # Impedance Value

Demand Input 0 Brown Green

1 2

16.3 to 17.0 KΩ *

Analog Output 0 Yellow Black

13 14

High Impedance ** > 200 KΩ

Analog Output 1 White Grey

15 16

High Impedance ** > 200 KΩ

Solenoid Power Orange Red

19 20

High Impedance > 1.0 MΩ

Electronics Power Violet Blue

21 22

High Impedance > 200 KΩ

Discrete Input 0 (option)

WHT/VIO WHT/BLK/VIO

23 24

High Impedance > 200 KΩ

Fault Alarm Output 0 WHT/ORN WHT/BLK/ORN

31 32

High Impedance *** > 200 KΩ

* Reference Figures 1.14 and 1.15 ** Reference Figures 1.16 and 1.17 *** Reference Figure 1.19

Table 5-1. XVG/eXVG Expected Circuit Impedance

Note. All impedance measurements shall be performed with no power applied to the XVG/eXVG and the wire pair under measurement is disconnected from the system.

5.2 Retrieving The Fault File

First establish communication with the XVG/eXVG via the serial RS232 or RS485 (optional) interface. Use the XView software to upload the fault file from the XVG/eXVG. Only electronics power to the unit is required to upload the fault file. Contact Precision Engine Controls Corporation to request a copy of the XView software. See the XView manual for additional details about uploading the fault file.

CH. 5: TROUBLESHOOTING THE XVG/eXVG 67

5.3 Fault Diagnosis

The XVG/eXVG continually monitors system operation parameters. If one or more parameters are out of range for the prescribed time limit, the valve registers a fault and shuts down. Table 5-4 lists the faults.

Pressure Faults A pressure fault indicates a pressure sensor failure or an external system problem. Check the fault and investigate the source of the over- or under-pressure condition. In the case of a sensor malfunction, return the valve to Precision Engine Controls Corporation for repair or replacement. Contact Precision Engine Controls Corporation for Return Material Authorization (RMA) before shipping the valve back to the factory.

Gas Temperature Faults A gas temperature fault indicates either a temperature sensor failure or an external system problem. Check the fuel temperature and adjust accordingly. Continued operation beyond valve operating range is not recommended. In the case of a sensor malfunction, return the valve to Precision Engine Controls Corporation for repair or replacement. Contact Precision Engine Controls Corporation for Return Material Authorization (RMA) before shipping the valve back to the factory.

Tracking Error Fault A tracking error indicates friction buildup in the XVG/eXVG mechanical system. Debris around the orifice or flow tube could be the cause. Clean the orifice and flow tube to correct this fault. Refer to Section 4: Maintaining the XVG/eXVG for instruction on how to properly clean the flow tube and orifice.

The tracking error fault will only enunciate when feedback is 0.025 inches greater than demand.


Symptom Probable Causes Corrective Action

No valve feedback Electrical wires not connected

No or low 24 VDC power

Incorrect Output Set-Up

Ensure wires connected to terminal 13, 14, 21, 22

Ensure 24 VDC across terminal 21 and 22

Ensure proper A/O Channel set-up

Valve does not track fuel Demand

Solenoid wires not connected

Solenoid wires reversed

No or low 24 VDC power level

Incorrect Set-Up

No fuel Demand

Ensure wires connected to terminal 19 and 20

Ensure solenoid power and return connected.


Ensure valve is in desired operating mode Verify that Demand signal format being used matches setting shown in the PDN Verify that the inlet pressure is at least 20 psid greater than the outlet pressure

Ensure wires connected to terminal 1, 2 and that Demand > minimum value

Valve does not hold consistent position-oscillates or dithers

Varying fuel Demand signal


Improper grounding

Ensure stable fuel Demand at the valve


Ensure shields connected per Fig. 1-20

Valve closed feedback >4.1 mA

Flow tube seal fouled

Improper grounding

Non-conforming SAE flange

Remove orifice and clean debris

Ensure shields connected per Fig. 1-20

Ensure pipe flange is flush mounted

Valve leaks when closed Flow tube seal fouled

Valve installed backwards


Ensure flow direction matches FLOW arrow

RS232 or RS485 Interface Inoperative

Incorrect wiring


COM1 not connected

Ensure connected to terminal 39, 40, 41


Check laptop/PC com port

Table 5-2. XVG/eXVG Initial Installation Troubleshooting Chart


Symptom Probable Causes Corrective Action

No position feedback No or low 24 VDC power

Self protective shutdown


Upload Fault File- check for faults. Take action on any faults found.

Valve does not track fuel Demand


No fuel Demand

Self protective shutdown


Ensure wires connected to terminal 1, 2 and Demand > minimum

Upload Fault File- check for faults. Take action on any faults found.

Valve Leaks when closed

Flow tube seal fouled

Seal damaged


Remove and replace seal

Table 5-3. XVG/eXVG In-Service Troubleshooting Chart

WARNING

The user must ensure proper 24 VDC electronics power levels, because the XVG/eXVG will NOT produce a fault signal if the 24 VDC electronics input power does not meet specifications. The 24 VDC power is converted to ±15V and 3.3V within the XVG/eXVG for use with the internal components. A fault signal will only be triggered if the ±15V or 3.3V power levels are out of their respective ranges.

Critical Faults

The following are considered critical system faults because they may be indications of major problems with the valve.

• 3.3 V

• ±15V

• Tracking error

• LVDT sensor

• Pressure sensor (inlet or outlet)

• Setup checksum

• Temperature sensor (gas or electronics)

• Watchdog


Contact Precision Engine Controls Corporation for assistance with troubleshooting if any of these faults are encountered. The valve may need to be returned to Precision Engine Controls Corporation for repair or replacement. Contact Precision Engine Controls Corporation for Return Material Authorization (RMA) before shipping the valve back to the factory.


Fault Description Fault # Limit Set Time Fault Action 3.3V – low 1 2.97 40 ms Shutdown 3.3 V – high 2 3.63 40 ms Shutdown Tracking 10 Pos. ≥ 0.025in. over

Demand 1 sec Shutdown

Gas Temp. – low 21 –20 °C 1 sec Warning Gas Temp. – high 22 130 °C 1 sec Warning Gas Temp.– shutdown 23 140 °C 10 sec Shutdown Inlet Pressure – low 41 5.0 psia 100 ms Shutdown Inlet Pressure – high 42 520 psia 100 ms Shutdown Outlet Pressure – low 51 5.0 psia 100 ms Shutdown Outlet Pressure – high 52 520 psia 100 ms Shutdown LVDT A+B – low 61 0.01 40 ms Shutdown LVDT A+B – high 62 0.04 40 ms Shutdown LVDT A–B – low 63 –0.04 40 ms Shutdown LVDT A–B – high 64 0.04 40 ms Shutdown LVDT pos limit 65 0.2625in. 40 ms Shutdown Setup checksum 70 n/a 0 ms Shutdown Flow setup 80 n/a 0 ms Warning Solenoid Current 90 Factory-configurable n/a Warning Inlet overpressure 101 515 psia (eXVG)

450 psia (XVG) 100 ms Warning

Outlet overpressure 102 515 psia (eXVG) 450 psia (XVG)

100 ms Warning

+15V – low 110 13.5V 40 ms Shutdown +15V – high 111 16.5V 40 ms Shutdown –15V – low 120 –16.5V 40 ms Shutdown –15V – high 121 –13.5V 40 ms Shutdown Elec. Ambient Temp. – low 130 –50 °C 1 sec Shutdown Elec. Ambient Temp. – high 131 125 °C 1 sec Shutdown Watchdog 150 n/a 5 ms Shutdown

Table 5-4. System Health Parameters and Limits



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APPENDIX A: DECOMMISSIONING & DISPOSAL

This section contains recommended XVG/eXVG decommissioning and disposal practices. It is for permanent removal or replacement of the installed product, with no intentions of rework, overhaul, or to be used as spares.

Decommissioning For removal follow proper lockout /tagout procedures and verify no live electrical circuits:

• Disconnect the 4 power wires, whether part of the integral wire

harness or connected to terminals, from the system power supplies or batteries.

• Disconnect the 9 or 11 signal wires, whether part of the integral wire harness or connected to terminals, from the system circuitry.

Disposal Follow local environmental codes in regards to disposal of electronic components, specifically all electrolytic capacitors.

Decommissioned units may also be returned to Precision Engine Controls Corporation for disposal in most cases. Contact the factory for details and return authorization before shipping decommissioned units.

APPENDIX A: DECOMMISIONING & DISPOSAL 75


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Documents

Precision XVG Fuel Valve