Answer / r.murugan

PID -IS THE ONE OF THE CLOSED LOOP CONTROLLER

DCS- (DISTRIBUTED CONTROL SYSTEM ) COMPLETE PLANT WILL BE
AUTOMAISED

Answer / nirav naik

I think he want to ask what is the difference between DCS &
PLC.
SO the answer is:
PLC stands for PROGRAMMABLE LOGIC CONTROLLER.
DCS stands for DISTRIBUTED CONTROL SYSTEM.

DCS = PLC+SCADA
PLC is software(ladder logic programming) and hardware
(power supply+cpu+i/o cards) which does process like
timing, counting, arithmatic, logic which is used to
activate and control the process.
SCADA= SUPERVISORY CONTROL & DATA ACQUISITION SYSTEM which
is used for making plant mimics which we are seeing on
operator DCS panel.
For more refer book S.K.SINGH

Q1: Consider part of a control loop, which excludes the transmitter, consisting of a process, a controller and a control valve which may be represented by two dead times of 0.5 min each and three exponential lags of 0.8 min., 1.0 min. and 1.5 min. respectively. We wish to express this system as an overall first order plus dead time (FOPLD) model ie gain, time constant and process dead time. (We will see later that this is often done, to simplify controller tuning). For this exercise, gain is considered to be 1.0. (A) If the transmitter is a flow transmitter whose behaviour can be described by a dead time of 0.2 min. and an exponential lag of 0.5 min. in terms of the overall dead time and overall first order lag how can the system behaviour be approximated ? Overall dead time = Overall time constant = (B) If the transmitter is a temperature transmitter with a temperature sensor in a protecting well whose behaviour can be described by a dead time of 0.7 min. and an exponential lag of 15 min. how can the overall system behaviour be approximated now? Overall dead time = Overall time constant =

0 Answers  

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