The Temperature Control System.

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ABSTRACT

The o bjective o f the project was to develop a t e mp e ra t ur e co n trol
syste m for maint ai ning a prese t se qu e n ce of s pecified temperatures in
a liquid substance during the mixing p rocess in a boiler. The de po\:v er
suppl y is res ponsible · for po wering each pa rt of the sys t e m . T he
temperature of the liquid chemical is sensed by a temperature-sen s itiYe
re s i st o r called a therm is t o r. The t em p erat ur e of the c h emi cal m ixture
determine s the re s istance of the th ermist o r. The temperatur e- t o-vo lta g e
conversion ci r cui t produ ces an o utput vo lt age that i s prop ortion al to
the temperatu re. The output goes t o an analog-to- di gital converter
(A DC)

which

processo r

ad d s


co n vert s
the

the

vo lt age

appropriate

to

di g ital

scal in g

and

form.

The


lineari zat i o n

digital
to

the

di giti z ed vo l ta ge and sends i t to the heater co ntrol circuit th a t is
programm ed t o sequence throu g h a ser ies of se t-point temperature s
durin g th e mixing process. The heater control ci r cu it co mpar es the se tp oin t te mp era t ure

to

the actual

t e mperature- t o-vo lta ge
adjustment s

of t he


co nver si o n

beatin g

tempera tu re as mea sur ed
circuit

el eme n t.

and

The

m a ke s

details

b y the


the

p roper

of th e

de sig n

devel o ped were based on a Microch ip PI CI 6F84a, are d escri bed . The
pedag og i ca l

va l ue

of the

probl em · is

also

di s cussed


t h rough

a

d escript io n of some of th e key s te p s in th e de s i g n process. lt i s s hown
t hat sol uti on requ ir ed bro ad knowledge dr aw n from s ever a l engi n eering
d iscip line s

including

el t: c tr ical.

mechanical

and

e n grneen n g.

© Universiti Teknikal Malaysia Melaka


con t r o l

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