The 9903-543 (Model: 9903-543) is a high-integrity digital overspeed protection system belonging to the Woodward ProTech-GII family. This specialized panel is engineered to provide fail-safe monitoring and emergency shutdown capabilities for critical rotating machinery, including gas, steam, and hydro turbines. The 9903-543 (Part Number: 9903-543) utilizes a Triple Modular Redundant (TMR) architecture, incorporating three independent microprocessors and three separate magnetic pickup (MPU) inputs. By employing a 2-out-of-3 (2oo3) voting logic, the system ensures that a single component failure will not cause a false trip, nor will it prevent a necessary safety shutdown.
As an Energize-to-Trip (ETT) version, the 9903-543 (ProTech-GII: 9903-543) is configured such that the trip relays are normally de-energized and must receive power to initiate a turbine shutdown. This specific logic is frequently required in plant safety architectures where the prevention of unintended trips due to control power loss is a priority. With a response time of less than 12 ms, this device provides authoritative protection against mechanical overstress, making it a standard in power generation and petrochemical facilities worldwide.
The 9903-543 (9903-543) provides precision speed sensing and robust communication for industrial environments.
| Parameter | Specification |
| Manufacturer | Woodward |
| Model Number | 9903-543 |
| Product Series | ProTech-GII Overspeed Protection |
| Trip Logic | Energize-to-Trip (ETT) |
| Voting Architecture | Triple Modular Redundant (TMR) 2oo3 |
| Input Power | 24 VDC (Supports Redundant Supplies) |
| Sensing Inputs | 3 Independent Magnetic Pickups (MPUs) |
| Response Time | < 12 ms (Typical) |
| Relay Outputs | Redundant Form-A / Form-C Relays |
| Communication | Modbus RTU (RS-485) / Modbus TCP (Ethernet) |
| Operating Temp | –20 °C to +60 °C |
| Dimensions | 482 mm × 310 mm × 143 mm |
| Weight | 6–7 kg (Industrial Chassis) |
| Compliance | Industrial-grade EMI/EMC Standards |
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