Woodward 9907-838 Steam Turbine Governor Control Unit

Description

Product Introduction

The Woodward 9907-838 is a compact Peak 150 digital speed control unit designed specifically for small to medium single-actuator steam turbines. Engineered for utility drive applications, this controller provides accurate turbine speed governing, automated startup ramp execution, and critical speed protection. It translates frequency signals from magnetic pickup (MPU) sensors into real-time demand signals to drive electro-hydraulic valve actuators.

Positioned as a cost-effective, purpose-built alternative to larger 505 series governors, the 9907-838 features pre-programmed control algorithms tailored for mechanical drive turbines. Its front-panel display and keypad interface allow field engineers to calibrate speed setpoints, PID gains, and valve limiters directly at the skid without needing external programming software or custom PLC code.

Key Technical Specifications

Application Scenarios & The “Trench” Experience

Picture this: It’s 4:00 AM on a freezing winter morning. A critical boiler feed pump steam turbine in a chemical processing plant trips unexpectedly due to an analog actuator driver failure on its old Peak 150 governor card. The plant steam pressure drops rapidly, threatening a full process cold-shutdown that costs $40,000 an hour. Having a pre-tested 9907-838 replacement ready on the shop shelf allows your instrumentation techs to swap the controller module into the panel door, reconnect the terminal strips, enter the saved speed ramp values, and re-establish boiler feedwater pressure in under 30 minutes.

• Petrochemical Plant Auxiliary Drives: Speed control on boiler feed pumps, lube oil pumps, and induced draft fans.
• Refinery Mechanical Drives: Governing small backpressure steam turbines driving process gas blowers.
• General Industrial Steam Skids: Managing mechanical drive turbines in paper mills, sugar mills, and food processing facilities.
• Marine Engine Auxiliary Systems: Speed control on auxiliary turbo-generators and seawater circulation pumps.

9907-838

9907-838

Transparency SOP: Quality Assurance & Testing

Every Woodward 9907-838 module undergoes a strict bench testing procedure prior to dispatch:

1. Inbound Visual & Hardware Audit: We inspect front keypad membranes, screen backlights, terminal block headers, and OEM serial tags for signs of damage or wear.
2. Power-On & Internal Rail Check: The unit is energized on a 24 VDC test bench to check current draw, internal power converter rails, and bootloader execution.
3. Dual-Channel Speed Frequency Sweep: Using signal generators, we feed frequency signals across 10 Hz to 10 kHz into both MPU channels to verify speed measurement accuracy and overspeed trip response.
4. Actuator Output Calibration: The actuator driver channel is swept across its full span while measuring 4–20 mA / 0–200 mA loop linearity under load.
5. Relay Load & Serial Communication Check: Output relays are load-tested and serial ports are polled using a Modbus master simulator to confirm register integrity.

The Veteran’s Tech Trap Guide

• ⚠️ Document All Parameters Before Removal: Before pulling a dead or malfunctioning 9907-838 unit, write down all configuration settings (such as speed ramps, overspeed limits, and PID gains) from the front display screen. Replacement modules ship with default settings and must be calibrated to match your specific turbine dynamics.
• ❗ Verify Power Supply Voltage Specs: The 9907-838 requires an 18–32 VDC logic supply. Applying 120 VAC or 230 VAC utility power directly to its power input terminals will ruin the internal power supply board instantly.
• ⚠️ Ground Speed Sensor Shields at the Controller Only: Connect MPU cable shielding strictly to the designated shield terminal on the 9907-838 chassis. Grounding both ends creates a ground loop that introduces noise, causing erratic speed readings or false overspeed trips.
• ❗ Check Actuator Output Jumper Configuration: Ensure the internal output stage jumpers match your hydraulic actuator requirements (whether 4–20 mA or low-impedance 0–200 mA coil). Incorrect jumper settings will restrict valve movement or trigger actuator fault codes.

Frequently Asked Questions

Q: What is the main difference between the Woodward Peak 150 (9907-838) and a 505 controller (9907-019 / 9907-167)?

A: The Peak 150 series is a streamlined, compact controller designed for basic single-actuator steam turbines with fewer I/O requirements. The 505 series offers expanded I/O, advanced startup modes, and broader program options for larger or more complex turbomachinery.

Q: Can a 9907-838 be used on an extraction or admission steam turbine?

A: No. The 9907-838 is built strictly for single-actuator steam turbines. Dual-actuator extraction or admission turbines require a specialized controller like the Woodward 505E (e.g., 9907-029).

Q: How do I clear an “Overspeed Trip” fault code on the display?

A: Once turbine speed falls below the overspeed reset threshold, press the front keypad RESET button or trigger the configured discrete “Remote Reset” input contact.

Q: Does this module support Modbus communication for DCS integration?

A: Yes. The 9907-838 includes a serial port supporting Modbus RTU protocol, enabling plant SCADA or DCS systems to read turbine speed, valve position feedback, and alarm statuses remotely.

Q: What warranty coverage applies to surplus or refurbished 9907-838 units?

A: Every unit supplied carries a complete 12-month operational warranty covering hardware components and functional performance.