Description
Woodward 9907-1199
Technical Specifications
- Protection Type: Independent hardware-based overspeed detection.
- Input Signal: Triple-redundant magnetic pickup (MPU) inputs for voting logic.
- Output Relay: High-capacity safety relay for fuel valve trip solenoid.
- Test Capability: Online test function to verify protection circuit integrity without tripping.
- Power Supply: Isolated power supply with watchdog monitoring.
Functional Features
- 2oo3 Voting Logic: Requires two out of three speed sensors to agree before initiating a trip, preventing nuisance trips.
- Independent Operation: Completely isolated from the primary governor control loops.
- Self-Testing: Continuous internal diagnostics and periodic online testing of relay outputs.
- Fail-Safe Design: De-energize-to-trip architecture ensures safety on power loss.
Application Scenarios
Critical for all industrial steam turbines, gas turbines, and high-speed reciprocating engines requiring API-compliant overspeed protection.
Performance Parameters
- Trip Accuracy: Better than ±1% of setpoint.
- Response Time: Millisecond-level relay dropout upon confirmed overspeed.
- Reliability: SIL-rated safety integrity level for critical protection.
Material Composition
Industrial-grade safety electronics housed in a ruggedized, EMI-shielded enclosure. Components are selected for extended temperature and vibration tolerance.
Structural Characteristics
- Form Factor: Compact module for panel or rack mounting.
- Indicators: Front-panel LEDs for power, normal operation, test active, and trip status.
- Connectors: Keyed multi-pin connectors to prevent miswiring.
Working Principle
The module continuously monitors three independent speed sensors. It applies 2oo3 voting logic to determine actual speed. If the calculated speed exceeds the programmed trip setpoint, the module de-energizes the safety relay, which closes the fuel valve trip solenoid and shuts down the prime mover.
Installation Requirements
- Install in a location protected from excessive vibration and EMI.
- Connect MPU cables using shielded twisted-pair wiring, grounded at the module only.
- Wire the trip relay in series with the fuel valve solenoid circuit.
Usage Precautions
- Never bypass or disable the overspeed protection module during operation.
- Perform regular online tests to verify relay functionality and sensor health.
- Document all test results and maintain a safety system log.
