Woodward VariStroke-DX, Инструкция по установке и эксплуатации

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Manual 35132 VariStroke-DX Duplex Hydraulic Servo Skid
Woodward 9
Figure 1-1. Basic VS-DX Application and Configuration
Designed as a stand-alone skid, servo-to-servo communication and automatic failover logic is included
within each servo forcing automatic transfers to the healthy servo with no external control logic or
interface required. Optionally, users can use a local switch or control driven relay connected to the skid to
routinely select and switch servo functions as the master and as the slave.
The VS-DX uses a specially designed fast-switching high signal select valve to ensure minimal control
switchover time and minimal system control pressure disturbance. During normal operation the In Control
servo will control the position of the connected VariStroke Hydraulic Power Cylinder (VHPC), while the
Not In Control servo is held in a standby mode with its pressure output port connected to the skid’s output
drain line. In this state, if the In Control servo or its input demand signal fail, the servo’s output is stepped
to a failsafe zero pressure level, the Not In Control servo is switched to an In Control state and begins
trying to control the VHPC, and the skid’s specially designed high signal select valve is then hydraulically
forced to connect the now healthy and In Control servo to the VHPC hydraulic pressure line.
Design Characteristics
The skid assembly has been designed to offer maximum reliability, especially for critical steam turbine
applications, and features include:
•
Ease of installation
•
Minimum hydraulic connections, reducing the potential for oil leakage
•
Compact design
•
Rapid control switchover (transfer) time
•
2 (two) Isolation valves which allow each VS-GI to be fully calibrated and checked before switching it
to on-line service
•
Dirt tolerant servos and shuttle valve
•
Online diagnostics and automatic switchover logic
•
Online replacement capability to safely and reliably disable, remove or replace the one of the VS-GI
without the need to stop the turbine or control system.
Released