Woodward 9905-976 ProTech 203 Overspeed Protection System

Overview

Configured for overspeed detection and trip execution in the ProTech 203 Overspeed Protection System, the Woodward 9905-976 (9905-976 Overspeed Protection System) provides direct electrical processing of three independent speed input channels and executes hardware voting logic for turbine shutdown. It accepts magnetic pickup signals, continuously compares channel status, performs internal diagnostics, and issues an overspeed trip within the specified response time while supporting online testing and module replacement.

Suffix Breakdown & Model Matrix

The supplied documentation identifies Woodward 9905-976 as a fixed catalog number within the ProTech 203 Overspeed Protection System product family. No official suffix matrix or ordering-code breakdown is specified in the available technical data.

Hardware Specifications

Actuator Loop Feedback Response

The ProTech 203 architecture evaluates three independent MPU channels using dedicated hardware voting instead of software-only decision logic. Consequently, the overspeed trip output remains available when a single sensing channel becomes unavailable or reports an abnormal condition. Furthermore, continuous CPU and MPU diagnostics allow channel status verification during operation, while online testing supports functional verification without interrupting the remaining protection channels. The maximum trip response time is specified as 40 ms following an overspeed condition.

Frequently Asked Questions

Q: Does the Woodward 9905-976 support online functional testing?
A: Yes. The module supports online testing, allowing diagnostic verification while the remaining protection channels continue operating according to the configured hardware voting logic.

Q: Can the module continue operating if one speed input channel fails?
A: Yes. The hardware implements a two-out-of-three (2oo3) voting architecture. A single MPU channel fault is detected and indicated while the remaining qualified channels continue participating in trip determination.

Q: Are weight and enclosure dimensions specified in the available documentation?
A: No. The provided technical information does not define the physical dimensions or module weight.

Field Installation Guidelines

• Verify that the incoming supply voltage matches the specified AC or DC operating range before energizing the module.
• Connect each magnetic pickup to its dedicated input channel using shielded instrumentation cable.
• Terminate cable shields according to the control cabinet grounding practice to reduce electrical noise on speed signals.
• Route MPU wiring separately from power cables, motor feeders, and switching circuits to minimize electromagnetic interference.
• Confirm channel polarity and sensor air-gap adjustment before commissioning the overspeed protection function.
• Perform online diagnostic verification after installation and confirm that all three speed channels report normal operating status before placing the protected machine into service.

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