ProTech SX

Woodward’s ProTech-SX SIL 2 PLC safety system applies to steam, gas, or hydro turbines, plus plant process equipment.  This stand-alone safety system accepts two speed inputs and seven discrete/analog inputs, uses programmed logic to determine when a safety event has occurred, then issues system shutdown commands and alarms. The ProTech-SX uses five fast-acting, configurable relay outputs and a speed meter output to interface with/command the specific system or device being protected.

The ProTech-SX is IEC61508 SIL-2 Certified and API670 & API612 Compliant


  • The ProTech-SX functions as a safety PLC, as it accepts seven discrete or analog inputs, and allows users to create custom safety/protection programs to protect site personnel and equipment. Programmers are able to utilize typical logic and testing sequence routines to create their application-specific safety logic and tests.

On-Line Testing

  • The ProTech-SX can be tested manually from the module’s front panel, Modbus communications port, or automatically via its auto-test routine function. The ProTech-SX allows users to configure overspeed or custom programmed tests to be performed manually or automatically.

Trip, Alarm, & Overspeed Logs

  • The ProTech-SX log function logs (saves to memory) all trips, alarms, trip valve response times, and overspeed events. The trip log function uses a scrolling buffer and records the last 50 sensed trip or alarm events and the last 20 overspeed events to memory, with associated times. Each log file can be viewed from the unit’s front panel, or downloaded to a computer via the ProTech-SX service tool program. Each module utilizes nonvolatile memory to ensure all logged events are saved, even on loss of power.

Trip Valve Health Monitoring

  • The ProTech-SX can be configured to test, log, and alarm on the response time of a turbine trip valve. Using the trooper’s built-in valve response monitoring function, users can connect a valve position sensor (limit switch, pressure switch) to a ProTech-SX input and configure the ProTech-SX to monitor, log, and alarm the time period between when a trip command was sent and when a valve closed indication was received.

Real Time Clock

  • Each ProTech-SX utilizes a real-time clock to ensure accurate time logging. Alternatively, one of the ProTech-SX inputs can be configured to accept a discrete clock synchronization input signal from a plant DCS or other time synch device.

High Resolution Displays

  • The ProTech-SX includes a highresolution 107 mm (4.2”) color display and keypad to allow users to locally monitor configuration settings, statuses, system inputs and outputs, and alarm, trip, and overspeed logs.

  Acceleration/Deceleration Detection

  • Optionally, this safety system can be configured to protect a turbine from high acceleration/deceleration events. The derivative of the speed signal is used to detect turbine/engine acceleration/deceleration and issue an associated trip command.

MPU Detection

  • The ProTech-SX’s speed-sensor input includes a special MPU open-wire detection circuit to validate that an MPU is properly connected before and during turbine operation. Note: Due to the difference in circuitry, this special, open-wire detection circuit is not available for use with active/proximity speed pickups.

Sulfur Contamination Resistant

  • The ProTech-SX utilizes a special conformal coating material that has demonstrated excellent long-term protection against H2S and SO2 gases at levels classified in international standard IEC 721-3-3 1994 - environment Class 3C2. 

03372 ProTech SX Product Specification 

26546V1 ProTech SX Product Manual (Vol. 1)

26546V2 ProTech SX Product Manual (Vol. 2)

51537 Protecting Your Assets 

51483 Safety Systems 


Related Applications