The Woodward 5437-1124 is a specific model variant of the ProTech-GII Overspeed Protection Device, featuring a Triple Modular Redundant (TMR) architecture. Engineered for the safety shutdown of steam, gas, and hydro turbines, this device accurately monitors turbine rotor speed and acceleration to prevent catastrophic overspeed events.
System Context and Core Function
The ProTech-GII is a SIL-3 certified safety device designed to safely shut down turbines upon sensing an overspeed or over-acceleration condition. It continuously monitors speed via active or passive magnetic pickups (MPUs) and issues a shutdown command to the turbine’s trip valve or corresponding trip system. The device’s 12-millisecond response time and wide speed range (0.5 to 80,000 rpm) make it suitable for all types and sizes of turbines.
Triple Modular Redundancy (TMR) Architecture
As a triple modular redundant system, the ProTech-GII consists of three independent modules (A, B, and C). Each module functions autonomously but cooperates through a 2-out-of-3 voting architecture to ensure high reliability and availability. This TMR design allows for online repair—a critical feature where any single module can be easily replaced while the turbine is running and operating normally, without causing a spurious trip.
Key Technical Features
Based on the official Woodward Product Specification (03370), the 5437-1124 and the ProTech-GII series offer several advanced features:
On-line Testing: Each module can be tested manually from the front panel or automatically via its auto-test routine. This allows for an overspeed test to be performed periodically on a per-module basis without taking the system offline.
High Availability Power Inputs: The system accepts two high-voltage power inputs (88-264 Vac/47-63 Hz; 90-150 Vdc) for redundancy.
Comprehensive I/O:
Speed Inputs: Three independent MPU inputs (100-32,000 Hz) or proximity probes.
Discrete Outputs: Two redundant trip relay outputs (2-out-of-3 voted) and one alarm relay output.
Analog Output: A dedicated 4-20 mA output for speed meter readout.
Communications: Modbus RS-232, RS-422, and RS-485 ports.
Sulfur Contamination Resistant: The device utilizes a special conformal coating demonstrating excellent long-term protection against H2S and SO2 gases, classified as level 3C2 under IEC 721-3-3 standards.
The device can be programmed via a front-panel keypad or a service tool on a laptop/PC. Password protection prevents unauthorized changes to configuration.
Certifications and Compliance
The ProTech-GII is built to meet stringent international standards:
Safety: IEC61508 SIL-3 Certified; TÜV SIL-3 certified per IEC 61508 Parts 1-7.
Hazardous Locations: CSA certified for Class I, Division 2; ATEX and IECEx certified for use in explosive atmospheres (Ex ec nC IIC T4 Gc).
Marine & Offshore: Compliant with ABS, DNV, Lloyd’s Register, and other major classification societies.
API Standards: Compliant with API670 and API612 requirements.
Application Scope
Designed for system-critical applications, the ProTech-GII is widely deployed in power generation and heavy industries, including:
Steam, gas, and hydro turbine power plants.
Compressor and pump drive turbines.
Turbines operating in harsh, corrosive environments (oil & gas, chemical plants) where high sulfur resistance is required.
