PLC Application & suggestions

[VEGASMAX]

I have a application that requires a PLC to controll the thermostats of two large a/c units in the following manner by overriding the t-sats via PLC. 1. Only one unit can start and run at the same time. 2. it can run for 14 min and then ask if the other unit needs to come on, if not it can remain running and then ask again in 14 minutes, or shut off when the desired temp is reached via t-sat. 3. The plc needs to be installed between both t-sats to controll the on off of each unit. 4. They can not ever start or run at the same time ...power is not avaiable to allow both to run or star together without tripping the breaker and the transformer is a 75KVA and that is only sised for one unit at a time. Please help with suggestions,wirring and programming suggestions
Ron
325-668-1015

 

[ADMIRALKEN]

This sounds like a fairly simple problem. Do these units already have a temp. control system? Does the system need to have manual overrides? What brand of PLC is already used at the facility? What brand support is available locally. Will this PLC be interfaced into a building management system?

Since you appear to be out of your area of expertise, I would recommend you hire a local automation job shop to do this for you.

Ken

 

[VEGASMAX]

cARRIER 20 TON PACKAGE UNITS...THE TEMP CONTROL IS TWO SEPRATE THERMOSTATS FOR TWO AREAS . aS FOR MANAU; OVERRIDE THE THERMOSATS SHOULD HANDLE THAT ok. SEIMANS IS IN THE AREA. tHANKS,
rON

 

[Beggar]

I'd second Ken's response. It sounds like you need the whole system designed. You probably need to hire somebody -- not likely to find a volunteer here who's going to do this whole job for you.

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[robotmagic]

Did you know that you can get a plc with thermocouple inputs, you can measure the temp differential and run the hvac which you need most!