Description
- Product Parameters
- Model Designation: WOODWARD 9905-068
- Control Type: Forward Acting (Speed Control and Load Sharing)
- Input Voltage: 20–40 VDC (24 VDC Nominal)
- Speed Range: 500 Hz to 15,000 Hz (High-Speed Sensing Support)
- Magnetic Pickup (MPU): 1.0 to 30 Vrms
- Load Sharing Output: 0–6 VDC (Proportional to Engine Load)
- Actuator Output Current: 0–200 mA (Standard Control Signal)
- Operating Temperature: -40°C to +85°C (-40°F to +185°F)
- Adjustments: Rated Speed, Idle Speed, Gain, Stability, Actuator Compensation, Droop
- Enclosure: NEMA 1 Aluminum Chassis (Surface Mount)
The Woodward 9905-068 is an analog electronic governor module from the 2301A series designed to manage speed control and proportional load sharing for prime movers, such as diesel engines, gas engines, or steam turbines. It operates on low-voltage DC input power and features forward-acting logic, increasing its 0–200 mA output current to open the fuel system whenever a speed or load correction is required. This device is highly valued in multi-generator setups, facilitating seamless isochronous load sharing or droop operation over a shared electrical bus.
Distinctions from Similar Models
- Voltage Configuration: Unlike its counterpart, the 9905-096 (which requires high-voltage 88–132 VAC / 90–150 VDC), the 9905-068 is optimized exclusively for standard low-voltage 20–40 VDC industrial batteries.
- Control Action: It utilizes Forward Acting circuitry, which distinguishes it from the 9907-005 model which uses reverse-acting logic to step down current output as speed rises.
- Tuning Potentiometers: Includes dedicated onboard multi-turn potentiometers for precise manual calibration of dynamic response parameters (Gain and Stability), allowing for tighter loop tuning than earlier legacy 2301 modules.
Product Operation Guidelines
- DC Power Polarity: Double-check the power input wiring to ensure positive and negative terminals are properly aligned; reversing the DC polarity can stress the internal input protection diodes.
- MPU Signal Quality: Use a dedicated shielded twisted-pair cable for the Magnetic Pickup (MPU) to eliminate ambient electrical noise. The shield must be grounded only at the 2301A chassis terminal and left floating at the engine block.
- Load Line Cross-Connections: For parallel generator operation, ensure the load sharing lines (0–6 VDC) are chained between units with uniform polarity. A reversed parallel line will cause immediate load hunting and grid instability.
- Droop vs. Isochronous Selection: If operating as a standalone unit on an infinite grid, ensure the “Droop” mode is active; keep it in “Isochronous” mode only when operating as an isolated multi-engine grid system.
