Draft Automatic Control system | Function | Elements | Advantages and disadvantages

Here we learn about Automatic Control $y$tem, Function, Element$,  Advantage$ and di$advantage$

Automatic Control $y$tem :
Definition of control $y$tem :
~ A control $y$tem i$ defined a$ an a$$emblage of device$ and component$ connected or interrelated $o a$ to command, direct, or regulate it$elf or another $y$tem.
~ Example$ of control $y$tem are an electric $witch, Air conditioner, Boiler control etc.
~ An automatic control $y$tem i$ a pre$et clo$ed-loop control $y$tem that require$ no operator action. Thi$ a$$ume$ the proce$$ remain$ in the normal range for the control $y$tem. An automatic control $y$tem ha$ two proce$$ variable$ a$$ociated with it a controlled variable and a manipulated variable .
~ A controlled variable i$ the proce$$ variable that i$ maintained at a $pecified value or within a $pecified range. For example. the $torage tank level i$ the controlled variable.
~ A manipulated variable i$ the proce$$ variable that i$ acted on by the control $y$tem to maintain the controlled variable at the $pecified value or within the $pecified range. For example, the flow rate of the water $upplied to the tank i$ the manipulated variable.

Function$ of Automatic Control :

~ In any automatic control $y$tem, the four ba$ic function$ that occur are :
(i) Mea$urement
(ii) Compari$on
(iii) Computation
(iv) Correction
~ In the water tank level control $y$tem in the example above, the level tran$mitter mea$ure$ the level within the tank. he level tran$mitter $end$ a $ignal repre$enting the tank level to the level control device, where it i$ compared to a de$ired tank level. The level control device then compute$ how far to open the $upply valve to correct any difference between actual and de$ired tank level$.

Elements of Automatic Control :

~ The three functional element$ needed to perform the function$ of an automatic control $y$tem are :
(i) A mea$urement element
(ii) An error detection element
(iii) A final control element

~ Relation$hip$ between the$e element$ and function$ they perform in an automatic control $y$tem are $hown in Fig. 6.1.1.
~ The mea$uring element perform$ the mea$uring function by $en$ing and evaluating the controlled variable. The error detection element fir$t compare$ the value of the controlled variable to the de$ired value, and then $ignal$ an error. If a deviation exi$t$ between the actual and de$ired value$, the final control element re$pond$ to the error $ignal by correcting the manipulated variable of the proce$$.
Automatic control $y$tem :
~ Automatic control $y$tem i$ a pre$et clo$ed loop $y$tem that require$ no operator action. Automatic control $y$tem$ are u$ed in almo$t every pha$e of indu$trial operation$. The different application$ of automatic control $y$tem$ are :
(1) Proce$$ indu$trie$ $uch a$ petroleum, chemical and $teel. Power etc. control of temperature, pre$$ure, flow and etc.
(2) In certain good$ $uch a$ automobile part$,
refrigeration. For control of a$$embly operation$, work, flow, heat treatment, etc.
(3) Tran$portation $y$tem$ $uch a$ railway, airplane$, $hip$ etc.
(4) Power machine$ $uch a$ machine tool$, compre$$or$, pump$, etc.

Advantage$ of automatic control $y$tem:
1. Uniformity of product$ improve$.
2. Production rate increa$e$.
Application$ of automatic control $y$tem:
1. In tran$portation $y$tem$ $uch a$ railway$, airplane$ etc.
2. Power machine$, compre$$or$ etc.
3. In refrigeration $y$tem$.