WOODWARD VariStroke GI single acting electro-hydraulic actuator: a reliable solution for turbine control

WOODWARD VariStroke GI single acting electro-hydraulic actuator: a reliable solution for turbine control

Overview

Woodward VariStroke GI is a single acting electro-hydraulic linear actuator designed to provide precise linear driving force for turbine control valves, valve frames, and trip and throttle valves (T&TV). This product series is suitable for mechanical or power driven steam turbines, using low-pressure hydraulic oil sources (usually turbine lubricating oil) as power sources, with high reliability, high redundancy, and strong environmental adaptability.

Main application areas

Steam Turbine Control Valves

Trip&Throttle Valves of Steam Turbine

Valve rack control

Replace old servo systems and power cylinders, suitable for renovation projects

Product Model and Configuration

VariStroke GI offers multiple models, and users can choose the configuration according to their actual needs:

Model applicable scenarios

Single acting integrated power cylinder turbine control valve

Single acting remote power cylinder turbine control valve

Integrated power cylinder turbine control valve with simplex oil release valve

Remote power cylinder with simplex oil release valve * turbine T&TV valve

Integrated power cylinder with drain valve interface * turbine control valve

Remote power cylinder with oil discharge valve interface * turbine T&TV valve

*Plan for future releases

Core functions and advantages

1. Fault safety design

Built in or external return spring ensures that the valve automatically closes to a safe position in case of shutdown or malfunction.

No need for expensive energy storage devices, the system is simple and reliable.

2. Redundant control and sensing

Supports dual redundant 4-20 mA input signals and dual redundant magnetostrictive displacement sensors (MLDT).

Even in the event of input or sensor failures, it can continue to operate, improving system availability.

3. Anti dirt design

Adopting corrosion-resistant materials, single action rotary valve, 50 pound chip shear force, and self-cleaning port design.

Suitable for harsh environments with severe oil pollution.

4. Quick oil drain valve option

Optional integrated quick oil drain valve, with quick response, can be directly driven by actuator servo or turbine shutdown system.

5. Soft stop function

Configurable 'soft stop' point to slow down valve closing speed and extend valve and seat life.

6. Side load capacity

The output shaft can withstand continuous lateral loads (up to 10% of the output force), using high-precision bearings and sealing technology to prevent oil leakage.

7. Configurable travel length

Support on-site adjustment of stroke length (not less than 50% of mechanical stroke) to meet different application requirements.

8. Suitable for hazardous areas

Compliant with international explosion-proof certifications such as ATEX, IECEx, CSA, etc., it can be used in Zone 2 hazardous areas.

Summary of Technical Specifications

Project Parameters

Position accuracy ± 2% of full range

Repetitive accuracy ± 1% of full range

Working temperature -40 ° C to+85 ° C

Oil supply pressure 3.45-34.5 bar

Input power supply 18-32 Vdc, 2.3A (steady state)

Protection level IP66 (IEC/EN 60529)

Travel range 50.8-304.8 mm (multiple options available)

The maximum thrust depends on the model and can reach up to 17800 kgf

Installation and maintenance

Supports any installation posture and provides multiple bolt modes.

Configure and diagnose through a computer-based service tool (RS-232).

Factory integration testing reduces on-site installation and debugging time.

Compliance and Certification

CE certification: Compliant with EMC Directive 2014/30/EU and ATEX Directive 2014/34/EU.

IECEx certification: applicable to hazardous areas (Zone 2).

CSA certification: Suitable for Class I Div. 1/Div. 2 environments in North America.

Compliant with the Pressure Equipment Directive (PED) and the Machinery Directive (MD).

Summary

Woodward VariStroke GI is a highly customizable, redundant, reliable, and environmentally adaptable electro-hydraulic actuator, particularly suitable for turbine control and safety systems. Its characteristics such as dirt resistance, soft stop, side load tolerance, and redundant control make it an ideal choice for improving the safety, availability, and automation level of steam turbine operation.