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 to make position transmitter feedback reverse i.e at valve close i want 20ma output and at full open 4ma.for the NELES positioner,model:ND8261/TS1.

3 Answers  

---

How Control valve sizing is done?

3 Answers  

---

difference b\w a transducer and a sensor

4 Answers  

---

what is actual drum level and compensated drum level?

0 Answers   APGenco,

---

Boiler flame scanner working principle?

1 Answers   Bhel,

---

---

please give me combustion cntrl interlock details? if possidle drawing also?for this one is there any website ?

1 Answers  

---

i install a DP transmitter of Faugi on drum level of boiler but i face a problem in it when i engergize the transmitter the meter shows 0 or 100% no variation in it.the distance of two points is 19.5 inches, i am in trouble please suggest me what can i do it's very urgent Please reply me as soon as possible Best regards ikraam haider

5 Answers  

---

HI, can anybody give details about GAS TREATMENT PLANT CONSTRUCTION,as INSTRUMENTATION ENGINEER what are the responsibilites.what are the instruments mainly instrumentation engineer will deal with

0 Answers   GSM, IOCL,

---

SOME OF YOUR QUESTIONS ARE NOT MAKING ANY SENSE SO TRY AND PUT IN A LITTLE BIT MORE EFFORT BEFORE YOU POST A QUESTION. WE WILL ONLY HELP THOSE WHO WE CAN SEE ARE TRYING TO HELP THEMSELVES.

0 Answers  

---

what is a vortex flow meter,mass flow meter and electromagnetic flow meter.particular use of this.means in which condition particular meter is used.

0 Answers   L&T,

---

What is the difference between antisurge

1 Answers  

---

Relation in MMWC to Flow rate

1 Answers  

---