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
The ProTech-SX is IEC61508 SIL-2 Certified and API670 &
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.
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.
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
- 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.
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
- 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.
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
- 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
ProTech SX Product Specification
26546V1 ProTech SX Product Manual (Vol.
26546V2 ProTech SX Product
Manual (Vol. 2)
Protecting Your Assets