controlling temprature

Newsgroups: sci.electronics.design
Date: 21 Aug 2005 08:29:51 -0700 Local: Sun, Aug 21 2005 6:29 pm Subject: plc control ACs Temp
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hi, i want a plc that can control three ACsas the following: when two ACs is ON, the third is OFF, and the are being switched: A B C 1 0 1 1 1 0 0 1 1
And there is some conditions: when the temprature reaches the degree X, the three ACs turn ON, and when the temp. reachs degree Y, only one AC turns ON and the others
set OFF.
I'm not a prof. in the PLC systems, but i couldn't find such a controler like this over the net, So if u plz can help of where i can find such product.
Thanks in advance
Hisham fikry
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If your temperature inputs are discrete ON-OFF inputs from say a wall thermostat, say input 1 = ON when > X and input 2 = ON when < Y then most PLC's can be programmed to do what you want. I'm assuming more AC's for more cooling to be the basic need.
There must be more info you need to supply, unless you just want: ( X and Y are your temps ) temp < y = A AC only ON temp > Y AND < X = A & B only ON temp > X = A and B and C ALL ON
If this is the case, above is your basic control logic
If you use a direct temp probe to PLC, then you need A/D input on the PLC.
Beyond this more info id needed. You also say that only 2 are on at any given time and the contradict that?
Dennis
hishoo11 wrote:

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