Valve Rack Linearization—Since flow-through single and staged inlet steam

valves tend to be non-linear throughout their flow range, turbine controls must be

de-tuned to compensate for instability or sluggish control points throughout this

range. As a way of allowing turbine control optimization, the VariStroke-I includes

an 11-point linearization table to allow turbine OEMs or users to compensate for

poor valve linearization by digitally linearizing the control-to-valve flow

relationship.

Side Load Capability—A common problem with turbine actuators is oil leaking

from their output shaft due to connection to valve rack linkages which have an

arc-type of motion. This motion results in side loading of the actuator shaft, and

after long periods may result in shaft-seal wear and resultant oil leakage.

Designed for a continuous side load of up to 10% of actuator output, the

VariStroke-I actuator incorporates a high-force precision bearing and triple-seal

technology on its output shaft to solve this typical application problem.