plc control ACs Temp

[hishoo11]

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

 

[John Popelish]

hishoo11 wrote:

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

The closest I have seen is a controller that minimizes the number of

cycles for each machine and distributes the cycles among all. Looked
at that way, your problem might be restated as, "if another machine is
needed, turn on the one that has been off the longest. If 1 less
machine is needed, turn off the one that has been on the longest. You
don't need to keep track of the actual time each machine has been on
and off, just a pair of ordered lists.

The decision of one more needed, or one less needed can either be
based on 4 separate setpoints, (temperatures at which-- none needed, 1
needed, two needed, 3 needed) or an integrating controller that
subtracts setpoint from measured temperature and integrates that
error, and whose output passes through those same 4 decision levels.

 

[Fred Bloggs]

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.

A= (TEMP >= X ) OR ( TEMP > Y )
B= (TEMP >= X ) OR ( TEMP > Y )
C= (TEMP >= X ) OR ( TEMP <= Y )