Woodward 9907-838 EasyGen Digital Governor Controller

Description

Technical Specifications:

• Model Number: 9907-838
• Manufacturer: Woodward, Inc. (Honeywell)
• Series: EasyGen 3500
• Controller Type: Digital Microprocessor-Based Governor
• Input Signals: Magnetic speed pickup (MPU), 4–20 mA, 0–10 VDC, frequency input (45–65 Hz)
• Output Signals: Dual proportional servo outputs (0–5 VDC or 4–20 mA), relay outputs (4× SPDT dry contacts)
• Power Supply: 24 VDC nominal (18–32 VDC range)
• Communication: RS-485 (Modbus RTU), CAN 2.0B, Ethernet (via option card)
• Display: 128×64 pixel backlit LCD with 4 navigation buttons
• Programming: Front-panel buttons or Woodward Toolbox software via RS-485/Ethernet
• Protection Functions: Overspeed, underspeed, overfrequency, underfrequency, high coolant temp, low oil pressure, overcurrent, reverse power, crank disable, start inhibit
• Mounting: DIN rail (EN 60715, 35 mm) or panel mount
• Operating Temperature: -20°C to +70°C (-4°F to +158°F)
• Storage Temperature: -40°C to +85°C (-40°F to +185°F)
• Humidity: 5% to 95% (non-condensing)

Functional Features:

• Dual Proportional Servo Outputs: Independently controls fuel actuator and valve position with 0.1% resolution
• Isochronous and Droop Speed Control: Switchable between 0% droop (isochronous) and 4–5% droop for grid or island operation
• Load Sharing: Supports up to 16 generators in parallel via droop-based load sharing without master-slave architecture
• Voltage Regulation (AVR Interface): Provides voltage setpoint and regulation when paired with Woodward voltage regulators
• Engine Protection Suite: 10 configurable protection relays with adjustable setpoints and time delays
• Frequency Bias: Adjustable frequency bias for load-dependent speed correction in droop mode
• Ramp Rate Control: Programmable acceleration and deceleration ramp rates from 0.1 to 100% per second
• Remote Start/Stop: Digital inputs for remote start, stop, and emergency shutdown via dry contacts
• Event Logging: Stores last 100 events with timestamps for fault diagnosis
• Front-Panel Navigation: Full configuration via LCD menu and 4 push buttons; no laptop required for basic setup
• Password Protection: 3-level access control (viewer, user, engineer) prevents unauthorized changes
• Synchronization: Built-in synchroscope function with voltage, frequency, and phase angle matching for grid paralleling
• Crank Disable: Prevents accidental start during engine cranking; requires crank signal to be inactive before start sequence initiates
• Start Inhibit: Blocks start command when protection conditions are active (low oil pressure, high coolant temp, etc.)

Performance Parameters:

Material Composition:

• Housing: UL 94V-0 rated flame-retardant polycarbonate/ABS blend (dark gray)
• Front Panel: Polycarbonate overlay with membrane keypad and LCD window
• PCB: FR-4 fiberglass epoxy laminate, conformal coated (ISO 16750 compliant)
• Terminal Blocks: Tin-plated phosphor bronze with screw-clamp connections
• Connectors: Molex Micro-Fit 3.0 series for internal wiring; Phoenix Contact for external I/O
• LCD Module: FSTN transflective LCD with LED backlight (white/amber)
• Internal Wiring: 22–26 AWG stranded tinned copper with PVC insulation
• DIN Rail Clip: Zinc-plated spring steel with locking tab
• Gaskets: Silicone rubber seal around front panel for dust protection
• Label: Laser-etched aluminum nameplate with model number, serial number, and ratings
• Isolation Barrier: Optocouplers (Si86xx series) with 1500 VDC isolation rating
• ADC Chip: Texas Instruments ADS1115 (16-bit, 4-channel, I2C-compatible SAR ADC)

Structural Features:

• Compact DIN Rail Module: Single-width design fits on standard 35 mm top-hat rail (EN 60715)
• Front Panel Layout: 128×64 LCD on left; 4 membrane navigation buttons (Up, Down, Enter, Esc) on right; LED status indicators (Power, Run, Fault, Alarm) along bottom edge
• Rear Panel: DIN rail clip, 2× analog input terminals, 2× analog output terminals, 8× digital input terminals, 4× relay output terminals, 4× digital output terminals, RS-485 terminal block, CAN bus connector, 24 VDC power terminal block, Ethernet option card slot
• Terminal Blocks: Screw-type terminals rated for 14–22 AWG wire; color-coded per function
• Side Vents: Small ventilation slots on both sides for passive cooling
• Bottom Cover: Removable bottom cover for terminal wiring access
• Top Cover: Fixed top cover with DIN rail mounting flange
• Option Card Slot: Right-side edge connector for Ethernet/IP card or CAN bus card

Working Principle:
The Woodward 9907-838 receives a speed signal from a magnetic pickup (MPU) mounted on the engine flywheel or gear. The MPU generates an AC voltage proportional to engine speed (frequency). The controller’s internal frequency-to-digital converter measures the input frequency with ±0.01 Hz resolution. The measured speed is compared to the user-programmed speed setpoint in the internal PID control loop. The PID controller calculates the error (setpoint minus actual speed) and generates a correction signal sent to the dual proportional servo outputs. Output 1 drives the fuel actuator (increasing or decreasing fuel flow); Output 2 drives the auxiliary valve (for starting, shutdown, or load limiting). In isochronous mode (0% droop), the controller maintains exact setpoint speed regardless of load changes. In droop mode (4–5%), speed decreases proportionally with load increase, enabling parallel load sharing among multiple generators without a master controller. The 10 protection relays continuously monitor engine parameters; if any parameter exceeds its setpoint for longer than its time delay, the corresponding relay activates, sending a shutdown signal to the fuel actuator and triggering the emergency stop output. The RS-485 and CAN interfaces allow remote monitoring and configuration via Woodward Toolbox software or a SCADA system using Modbus RTU protocol. The synchronization function compares the generator voltage, frequency, and phase angle with the grid bus; when all three parameters are within tolerance, the controller closes the breaker close output, connecting the generator to the grid.

Advantages and Highlights:

• Full Digital Replacement: Eliminates all electro-mechanical components; zero drift over time
• Front-Panel Programming: Complete setup via LCD and buttons; no laptop required for commissioning
• Dual Servo Outputs: Independent control of fuel and auxiliary valve with 12-bit resolution
• Isochronous + Droop: Single unit supports both grid-tied (droop) and standalone (isochronous) operation
• 16-Generator Load Sharing: True droop-based parallel operation without master-slave dependency
• 10 Protection Functions: Comprehensive engine protection with adjustable setpoints and time delays
• Event Logging: 100-event buffer with timestamps enables rapid fault diagnosis
• 3-Level Security: Viewer, User, and Engineer access levels prevent unauthorized configuration changes
• Modbus + CAN + Ethernet: Triple communication protocols for SCADA integration and remote monitoring
• Built-In Synchronization: Synchroscope function with voltage, frequency, and phase angle matching for grid paralleling
• Crank Disable: Prevents accidental start during engine cranking
• Wide Temperature Range: Operates from -20°C to +70°C; suitable for outdoor enclosure installations
• Woodward Ecosystem: Fully compatible with Easygen 3500 alternator controllers, UGT15/UGT25 actuators, and WGCP panels
• 10-Year Design Life: Components rated for 10+ years continuous operation in industrial environments

Applicable Industries:

• Power Generation: Diesel generator sets (50 kW to 10 MW), gas turbine generators, steam turbine governors, hydro turbine governors
• Oil and Gas: Pipeline compressor drives, wellhead power units, flare gas recovery turbines
• Marine: Ship propulsion diesel engines, auxiliary generators, bow thrusters
• Mining: Diesel-electric locomotive drives, haul truck power systems, underground ventilation fans
• Data Centers: Backup diesel generators (N+1 redundancy configurations)
• Hospitals: Emergency standby generators with automatic transfer switches
• Telecommunications: Cell tower backup power, central office generators
• Manufacturing: Combined heat and power (CHP) plants, cogeneration systems
• Military and Defense: Tactical generator sets, naval vessel power systems
• Renewable Energy: Biogas engine governors, waste-to-energy plant controllers

Model Series:

Installation Requirements:

• Mounting: 35 mm DIN rail (EN 60715) in a control panel or dedicated enclosure
• Enclosure Rating: Minimum NEMA 1 (indoor) or NEMA 4X (outdoor/washdown) if installed outside
• Ambient Temperature: Maintain enclosure interior at -20°C to +55°C for optimal performance
• Clearance: Minimum 50 mm (2 in) clearance above and below unit for ventilation
• Power Supply: 24 VDC regulated, filtered, and supervised per NFPA 110; maximum ripple <100 mV peak-to-peak
• Battery Backup: Required per NFPA 110; 24 VDC supply must have minimum 24-hour battery backup
• Grounding: Connect chassis ground to building equipment grounding conductor; ground resistance <1 Ω
• Cable Routing: Separate signal cables (speed pickup, analog I/O) from power cables (24 VDC, servo outputs) by minimum 100 mm (4 in)
• Speed Pickup Wiring: Use shielded twisted-pair cable for MPU signal; ground shield at controller end only
• Servo Output Wiring: Use shielded cable for analog outputs; ground shield at controller end only
• Terminal Torque: Tighten all terminal screws to 0.5 Nm (4.4 in-lb); re-torque after 72 hours
• Wire Gauge: Use 18–22 AWG for signal wires; 14–18 AWG for power wires
• Bus Termination: Install 120 Ω termination resistor at both ends of the RS-485 bus (per Modbus specification)
• Baud Rate Matching: Ensure all devices on the RS-485 bus use the same baud rate (set via front-panel DIP switches)

Usage Precautions:

• Do not exceed 32 VDC supply voltage: Overvoltage permanently damages internal circuitry
• Do not reverse polarity: 24 VDC must be connected with correct polarity; reverse polarity protection is not provided
• Do not exceed 65 Hz speed input: Input frequency above 65 Hz causes measurement errors and potential damage
• Do not disconnect speed pickup while engine is running: Loss of speed signal triggers overspeed shutdown; always stop engine before disconnecting MPU
• Do not modify protection setpoints without engineering approval: Incorrect overspeed or underspeed setpoints create safety hazards
• Do not bypass any protection relay: All 10 protection functions are mandatory per NFPA 85 and NFPA 110
• Perform insulation test before first use: Measure >100 MΩ at 500 VDC between all I/O terminals and chassis ground
• Test monthly per NFPA 110: Perform full functional test of governor, protection relays, and servo outputs at least once per month
• Do not operate above 70°C ambient: Exceeding temperature range voids warranty and degrades LCD and electronic components
• Replace every 10 years: Even if functional, capacitor aging and solder joint fatigue reduce reliability; replace per Woodward lifecycle recommendation
• Use only Woodward-specified cables: Speed pickup cable must be shielded twisted pair; servo output cable must be shielded
• Record all events: Export event log via Woodward Toolbox after every fault occurrence for regulatory compliance
• Do not cover ventilation slots: The unit requires airflow for thermal management; obstructing vents causes overheating
• Update firmware via authorized tools only: Use Woodward Toolbox software version 3.0 or later; unauthorized firmware voids warranty
• Lock engineer access with password: Set a unique engineer password to prevent unauthorized configuration changes
• Do not install in explosive atmospheres: The unit is rated IP20 (indoor only); use an intrinsically safe barrier in hazardous locations (Zone 1/2, Class I Division 2)
• Do not use for safety-critical functions without redundancy: This governor is not a safety instrumented system (SIS); use a dedicated safety controller (Triconex, FSC) for SIL-rated applications
• Verify phase sequence before first run: Incorrect phase sequence causes reverse rotation; correct sequence per drive manual
• Do not exceed 5000 RPM maximum speed: Overspeed will cause mechanical damage to the engine and governor actuator