WOODWARD VariStroke Hydraulic Power Cylinder (VHPC)

WOODWARD VariStroke Hydraulic Power Cylinder (VHPC): a heavy-duty actuator designed specifically for extremely hazardous environments

Overview

Woodward VariStroke hydraulic power cylinders (VHPC) are a series of heavy-duty hydraulic power cylinders designed for extremely hazardous environments in industries such as oil and gas, petrochemicals, and power generation. This product series can be used in conjunction with Woodward's VariStroke servo system and VariStroke DX hydraulic slide table to form a complete electro-hydraulic execution system for precise positioning of turbine control valves, valve racks, and trip and throttle valves.

Main application areas

Steam Turbine Control Valves

Trip&Throttle Valves of Steam Turbine

Valve frame drive system

Suitable for Zone 1 and Zone 2 hazardous areas

Product Model and Configuration

VHPC offers a variety of sizes and configurations, and users can customize according to their needs:

Model type applicable servo model optional functions

Dual acting power cylinder VariStroke-I/II without drain valve option

Single acting power cylinder (with drain valve interface) VariStroke GI/DX optional MLDT/LVDT sensor

Single acting power cylinder (integrated drain valve) VariStroke GI/DX optional quick drain valve

Core functions and advantages

1. Highly customizable

Support multiple piston aperture, stroke length, and return spring force selections.

MLDT (magnetostrictive) or LVDT (linear variable differential transformer) position sensors can be optionally selected.

Support single acting or double acting design to meet different hydraulic system requirements.

2. Quick oil drain valve option

Single acting models can be equipped with integrated quick release valves or release valve interfaces.

The oil discharge valve can improve the response speed of the actuator during large stroke changes and achieve the separation of the control system and the safety system.

The oil discharge valve interface supports users to connect dual redundant or triple redundant trip modules, suitable for high safety applications.

3. Side load tolerance

The output shaft can withstand sustained lateral loads up to 5% of the output force.

Adopting high-precision bearings and triple sealing technology to ensure long-term dry shaft operation and prevent oil leakage.

4. Resistant to high temperatures and harsh environments

Working temperature range: -40 ° C to+105 ° C (depending on the fuel supply temperature).

Compliant with IP66 protection level (IEC/EN 60529), dustproof and waterproof.

Through MIL-STD-810 impact and vibration testing.

5. Redundant sensor support

Optional dual redundant MLDT sensors provide high-precision position feedback and support operation in ambient temperatures up to 105 ° C.

6. Global Maintenance Network

Provide global repair and support through Woodward authorized service network.

Each power cylinder undergoes independent testing before leaving the factory to ensure performance and zero leakage.

Summary of Technical Specifications

Project Parameters

Oil supply pressure range 3.44-34.5 bar (50-500 psi)

Hydraulic oil type: mineral oil, synthetic oil, or Fyrquel EHC base oil

Recommended oil cleanliness level ISO 4406 20/18/16

Recommended viscosity of 20-100 cS

Return/discharge pressure ≤ 2 bar (29 psi)

MLDT sensor power supply 20.4-28.8 Vdc @ 100 mA

Analog output signal 2-channel 4-20 mA, load ≤ 500 Ω

The response time of the oil drain valve is fully open<250 ms, fully closed<2.0 s

Compliance and Certification

CE certification:

EMC Directive: 2014/30/EU

ATEX Directive: 2014/34/EU

Zone 1：II 2 G Ex db IIB T4 Gb

Zone 2：II 3 G, Ex nA IIC T4 Gc

IECEx certification:

Zone 1：Ex db IIB T4 Gb

Zone 2：II 3 G, Ex nA IIC T4 Gc

CSA certification:

Class I, Div. 1, Groups C&D T4

Class I, Div. 2, Groups A,B,C,D T4

Compliant with the Machinery Directive (2006/42/EC) and the Pressure Equipment Directive (2014/68/EU).

Typical Application Diagram

VHPC can be used in conjunction with VariStroke servo system for:

Positioning of turbine control valve

Trip and throttle valve drive

Redundant speed signal processing

Integration with turbine safety system

The system supports analog and discrete signal input, and provides valve position indication and trip status feedback, making it easy to integrate into DCS or PLC systems.

Summary

Woodward VariStroke Hydraulic Power Cylinder (VHPC) is a highly reliable, customizable hydraulic actuator suitable for extreme environments. Its side load tolerance, redundant sensing, quick release valve options, and global hazardous area certification make it an ideal choice for high safety and high availability control systems in industries such as oil and gas, petrochemicals, and power.