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ProTech‐GIIThe ProTech-GII is designed to safely shut down steam, gas, and hydro turbines upon sensing a turbine overspeed or over-acceleration event. The device’s 12 millisecond response time and 0.5 to 32 000 rpm speed range make it ideal for application on all types and sizes of turbines.

The ProTech-GII models with two dual-redundant relay outputs are design to be applied with simplex or dual-redundant trip block assemblies or trip systems. The ProTech-GII models with three independent non-voted output models are designed to be applied with special turbine trip block assemblies that perform the 2-out-of-3 voting within their design.

This fast acting overspeed protection device is designed to be applied in conjunction with a turbine control or trip system to safely shut down the turbine. Interface with related control systems or plant DCS(s) (Distributed Control Systems) can be performed via the ProTech-GII’s redundant hard-wired input and output signals or through its triple-redundant serial Modbus communications ports. Optionally Ethernet gateways can be purchased to easily interface with plant Ethernet networks.

Certified as an IEC61508 SIL-3 (Safety Integrity Level Three) safety device, the ProTech-GII can easily be applied within an IEC61508 or IEC61511 based safety system. A thorough product manual is provided to instruct users on how to apply the ProTech-GII to meet IEC based requirements.

Designed for system-critical applications, the ProTech-GII’s triple-modular architecture coupled with its on-line testing and on-line repair capabilities give it one of the highest availability and reliability ratings in the industry.


The ProTech-GII is an overspeed safety device designed to safely shut down steam, gas, and hydro turbines of all sizes upon sensing an overspeed or overacceleration event. This device accurately monitors turbine rotor speed and acceleration via active or passive MPUs (magnetic pickups) and issues a shutdown command to the turbine’s trip valve(s) or corresponding trip system.

Depending on the system design, the ProTech-GII can be purchased with two dualredundant trip relay outputs using a 2-out-of-3 voted architecture, or with three independent non-voted trip relay outputs. Individual alarm relays, 4–20 mA speed readouts, and Modbus ® * communications make this overspeed device easy to integrate into any turbine safety system.

*—Modbus is a trademark of Schneider Automation Inc.

The ProTech-GII is available in flush-mount models designed to be installed within a standard 24” (610 mm) cabinet front door, or models designed to be bulkhead mounted on a wall or skid near the turbine set. Designed for harsh environments when installed within an enclosure, this device has an ingress protection rating of IP56 (protected against dust and completely protected against jets of water of similar force to heavy seas).

Designed for high reliability, each ProTech-GII module (A, B, C), depending on the purchased model, accepts two high-voltage power inputs (90–240 Vac / 100–150 Vdc) or one high-voltage power input (90–240 Vac / 100–150 Vdc) and one lowvoltage power input (18–32 Vdc). This design works on a high-signal-select basis, allowing the unit to fully operate with either or both power sources available.


Overspeed Protection Device

Product Specification 03370


  • IEC61508 SIL-3 Certified
  • API670 & API612 Compliant
  • 2-out-of-3 voting
  • High availability (TMR)
  • Acceleration protection
  • On-line testing
  • On-line repair
  • Overspeed trip and test logs
  • Modbus communications
  • Password security protection
  • 12 millisecond response time (independent voted output models)
  • Internal frequency generator
  • Optional Ethernet communication gateway

Fact sheet

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