Interested to Buy Any Domain ? << Click Here >> for more details...
Answer Posted / warren holden
Yes, a control valve can be used without a positioner.
Some of the previous responses contain correct information
about certain elements of what a positioner actually does
however they do not address the fundamental issue from a
control perspective.
The positioner on control valve is essentially a cascade
(inner) loop acting as a high gain proportional controller
within the external (outer or master) loop (Shinskey, G.F.
1988). The positioner will be beneficial if its response
time constant is faster than the master loop element(s)
i.e. in the case of a temperature control (master) loop the
control valve positioner dynamics will undoubtedly be
faster than the temperature measurement change dynamics
(this being a fundamental requirement of cascade control).
However, the control valve positioner is of no use, and
actually a hindrance, on fast acting master loops i.e. flow
control with fast change dynamics. Hence control valve
positioners are often not used on flow control loops where
the outer (master) loop flow measurement and associated
controller can handle the control valve positioning quite
well themselves.
| Is This Answer Correct ? | 1 Yes | 0 No |
Post New Answer View All Answers
detail of mass flow meter pricipal
IS there any effect of vortex in low pressure side of the transmiter after the orific in feed water line? if yes then what is the calculation?
What is megering????
How digital input and digital output 's are working in dcs
What you mean by multi stage control vavles?
my data card only does run in my mobile so how can change it that it run other mobile & computer and i can stor data in my data card
I m appointed as an automation trainee engineer in small firm in that I am only the one , my company give me a project on s7-200 as i m beginner I don't know how to program so please send me the helpful site so that I complete my project before deadline....please help me out in this critical situation.
1.can you use SCADA instead of DCS,DCS instead SCADA 2.Difference between DCS and PLC,can their role be reversed i.e. role interchange 3.Difference between RTU and PLC
Make Heater Process Logic.
how to check earthing,what is minum ohms for proper earthing
Who to difference between analog in & analog out in dcs?
Where are oxygen analysers installed in cfbc boilers? What are their usual readings?
Differentiate between ultrasonic flowmeter and radar type flow meter
What is the purpose of LO Overhead tank in turbines.
Whatis the reset ofset and control system in instrumentation
