Description
Key Technical Specifications
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Model Number: 9905-930
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Manufacturer: Woodward
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CPU: 505 Digital Control (32-bit)
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Speed Input: Magnetic pickup (MPU) 1–35 kHz, 0.5–60 V p-p
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Analog I/O: 4 × 4–20 mA in, 6 × 4–20 mA out, 12-bit
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Relay Outputs: 8 Form-C, 5 A @ 28 VDC / 120 VAC
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Valve Driver: ±200 mA into 40 Ω coil, 24 VDC supply
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Communications: Modbus RTU RS-485, 19.2 k default
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Power: 18–32 VDC, 25 W max
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Operating Temperature: –40 °C to +70 °C
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Enclosure: ABS bulkhead box, IP54, 12″ × 10″ × 6″
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Certification: CE, UL 508, Class 1 Div 2 Groups C/D optional
Woodward 9905-001-L
Field Application & Problem Solved
Packaged 1 MW steam-turbine skids used to ship with a naked 505 board loose in a panel—field guys had to land every wire, build a valve driver, and hope the screen didn’t fill with metal dust. The 9905-930 is Woodward’s answer: a pre-wired 505 already married to a terminal strip, valve driver, and relay card, all bolted inside a gasketed box. You mount it on the skid, bring in MPU, PT, CT, and trip solenoid, and you’re syncing to the grid in two hours. I deploy it on landfill-gas engine gensets and small back-pressure steam units where floor space is tight and downtime is money. The real value: every critical wire lands on numbered terminals—no guesswork, no late-night “where does the speed probe shield go” phone calls.
Packaged 1 MW steam-turbine skids used to ship with a naked 505 board loose in a panel—field guys had to land every wire, build a valve driver, and hope the screen didn’t fill with metal dust. The 9905-930 is Woodward’s answer: a pre-wired 505 already married to a terminal strip, valve driver, and relay card, all bolted inside a gasketed box. You mount it on the skid, bring in MPU, PT, CT, and trip solenoid, and you’re syncing to the grid in two hours. I deploy it on landfill-gas engine gensets and small back-pressure steam units where floor space is tight and downtime is money. The real value: every critical wire lands on numbered terminals—no guesswork, no late-night “where does the speed probe shield go” phone calls.
Installation & Maintenance Pitfalls (Expert Tips)
Tighten the Bulkhead Screws or the Box Becomes a Rain Funnel
IP54 only works if the lid gasket is compressed. I torque the four corner screws to 20 lb-in and run a bead of silicone across the top edge—cheap insurance against driving rain on an open skid.
IP54 only works if the lid gasket is compressed. I torque the four corner screws to 20 lb-in and run a bead of silicone across the top edge—cheap insurance against driving rain on an open skid.
Use Shielded Pair for MPU—Ground ONE End
The 505 is picky; 60 Hz hash on the speed input makes the valve dither and the kW line look like an EKG. I run #18 shielded twisted pair, ground the shield at the box, and keep it out of the 480 V bucket.
The 505 is picky; 60 Hz hash on the speed input makes the valve dither and the kW line look like an EKG. I run #18 shielded twisted pair, ground the shield at the box, and keep it out of the 480 V bucket.
Check Valve Driver Null Before You Close the Breaker
Power up, go to “Manual,” set 0 % demand—valve current should read 0 mA ±1 mA. If it’s offset the actuator will creep open and you’ll overspeed on start. Use the front-panel trim to zero it.
Power up, go to “Manual,” set 0 % demand—valve current should read 0 mA ±1 mA. If it’s offset the actuator will creep open and you’ll overspeed on start. Use the front-panel trim to zero it.
Label the Relay Functions on the Lid
The eight Form-C contacts are programmable; default labels don’t tell the story. I print a strip of Dymo tape: “K1 = Gen Breaker,” “K2 = Trip Sol,” etc., and stick it inside the lid—next tech thanks you.
The eight Form-C contacts are programmable; default labels don’t tell the story. I print a strip of Dymo tape: “K1 = Gen Breaker,” “K2 = Trip Sol,” etc., and stick it inside the lid—next tech thanks you.
Woodward 9905-001-L
Technical Deep Dive & Overview
The 9905-930 is a 505 Digital Control pre-packaged into a rugged bulkhead enclosure. Internally the 505 board talks to a daughter-card that holds the valve driver (current source), relay drivers, and a pluggable terminal strip. Speed signal comes in on a two-piece screw terminal, gets conditioned by an LM2907 frequency-to-voltage chip, then hits the 505’s 12-bit A/D. Control loop is PID with acceleration limiting; output is a ±200 mA command into a 40 Ω servo coil. Eight relays provide breaker close, trip, alarm, and load-sharing interlock; all contacts are Form-C, 5 A rated. Modbus RTU sits on a three-pin header so you can remote-speed-trim or pull alarms into a SCADA node. Revision 930 swaps the original tin-plated terminals for nickel-plated ones and upgrades the box gasket to silicone—cheap insurance against corrosion in coastal or paper-mill sites .
The 9905-930 is a 505 Digital Control pre-packaged into a rugged bulkhead enclosure. Internally the 505 board talks to a daughter-card that holds the valve driver (current source), relay drivers, and a pluggable terminal strip. Speed signal comes in on a two-piece screw terminal, gets conditioned by an LM2907 frequency-to-voltage chip, then hits the 505’s 12-bit A/D. Control loop is PID with acceleration limiting; output is a ±200 mA command into a 40 Ω servo coil. Eight relays provide breaker close, trip, alarm, and load-sharing interlock; all contacts are Form-C, 5 A rated. Modbus RTU sits on a three-pin header so you can remote-speed-trim or pull alarms into a SCADA node. Revision 930 swaps the original tin-plated terminals for nickel-plated ones and upgrades the box gasket to silicone—cheap insurance against corrosion in coastal or paper-mill sites .
