Answer / md. jawed akhtar

In open -loop control system, the input has no control over
output variable.
where as in close-loop(or feedback)control system,the input
has control over output variable.In this system,the variable
output is measured and feed to the controller through path(or
loop).In controller compares the desire reference value with
the actual value and acts to reduce the difference between the
two to zero value.

Answer / carl_ellis

An open loop has no feedback, like a timed operation. For
instance, an irrigation system operates for 45 minutes per
day, starting at 10:15 AM. It does this whether the water
is needed or not, because the controller, the timer, has no
feedback about the need for water.

A closed loop uses feedback. In the irrigation example, a
soil moisture sensor provides feedback to a controller to
let the controller make a decision as to whether irrigation
is needed and for how long.

Carl Ellis
Measure First

Answer / sunil.onthekadu77

open loop means
only for indication
but close loop
means suppose
transmitter output
effect the final
controle valve such
as controle
valve,dampers,pumps
etc.

Answer / r_vaya

In close loop has directly control on output , in open loop not possible. 

how u calibrate pneumatic n motorized c/v?

0 Answers  

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pt range is -45 psi to 45 psi.friends can you give answer with calculation and with linerity scale like 0%,25%,50%,75%& 100%?

1 Answers   WB,

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Manipulation of dead wt. tester double piston type.

0 Answers   CCIE,

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what is dry leg and wet leg in transmeter calibration?

3 Answers  

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Which standard is used for calibration of Control Valves ?

2 Answers  

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please send me some question papers of HPCL aptitude test ?? please send it to bipinb.28@gmail.com ...

0 Answers   HPCL,

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What is the diffrence between ff tx and non ff tx

0 Answers   Jindal, Rosemount,

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2 Answers   L&T,

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i want the equation of this question. Tranmitter range is 120 mmwc and dcs flow range is 1700 nm3/hr. if i want to change dcs range from 1700 to 2400 nm3/hr then how much dp i have to enter in transmitter

2 Answers   GMR,

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why do we use 4-20 ma current why cant o-20ma

6 Answers   Southwest Cheese,

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the pump holds on run indication into the dcs and filed local control panel remote push button condition operaton wrong like when the push button pushing conditions the pump is off and the push button release condition the pump is on totally opposite condition . And control room inside give the stop command into dcs just 1secon relay engage and again normal condition. How can I slove

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please send me gail format if u have... please help me if u can...

1 Answers  

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