John Egnew, Fisher-Rosemount Educational Services

Articles

Mechatronics and Motion Control October 1, 1999

Positioner Guidelines

G uidelines are never a substitute for good engineering practices and experience but they are better than proceeding down a trial-and-error learning path. Guidelines for all positioner types Positioners can reduce control valve deadband caused by friction. Most control valves without positioners, even those using 'low friction' packing material, may demonstrate a 5% deadband. Deadband greater than 1% can produce loop controllability problems.

By John Egnew, Fisher-Rosemount Educational Services
Control Systems May 1, 1999

Open-Loop Response Testing Improves Process

Three-quarters of all process control loops are operating below peak efficiency, according to one industry survey. Among conditions that can reduce process efficiency are improper control valve selection, sizing, or calibration; instability or oscillation above and below a setpoint; slow response to changing conditions; or a combination of these factors.

By John Egnew, Fisher-Rosemount Educational Services
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