System controller recommendations ? PLC ?

[Nihilist]

Hi,

First off I will give a bit of info about myself , followed by my question.

I am an electrician for 6 years, having gone through a 5 year apprenticeship via the IBEW . I have taken a class in PLC's (part of the apprenticeship), but have no actual "in the field" experience with them, only labs done in class. I have also taken an HVAC controls class, and an Instrumentation and Controls class and have some experience with controls systems ( audio amplifier building is also a hobby of mine ). I am familiar with most of the HVAC terms, but not very familiar with names or model #'s of different controllers.


My question is this. I just started working for a local company that uses modified commercial freezers (think frozen pizza section at the supermarket, 2 and 3 door units) . These freezers will be run in 3 seperate cycles ( a freeze cycle, a deep freeze cycle, and a maintenance cycle), and we will be adding instrumentation to monitor temperature at various places inside the cabinet and coolant/compressor temperatures as well. Relative humidity in the cabinet will also be monitored .

Approximately 30 inputs will be needed on the controller/PLC , most of them analog . Approximately 25 outputs will be needed to switch on fans, compressor , heaters, etc .

This system needs to be able to show all the data from each of the sensors in real time (or within a reasonable delay time of a few seconds), and should be able to perform 3 different freezing cycles/programs , along with the capability of being connected to the internet (wirelessly would be a plus)for monitoring and remote operation/adjustments.


Based on my very limited experience and searching on the internet, I was originally thinking about using a PLC setup with something like WonderWare. However, I searched and came across this forum , in particular this thread : http://hvac-talk.com/vbb/showthread.php?t=750451

After reading this thread, I have begun to wonder if a PLC based system would best suit this application. I would be grateful if you could steer me towards what system or system type you feel would be best for the system I have described.

The PLC system or other HVAC controller and program will be setup by a company that specialises in that area, I will be installing all the sensors in the cabinet.

Cost is a consideration, this is a small company with a limited budget.

In summary, I would like to know:

1)What controller type do you feel would be best suited for this system ? PLC or other ? A small description about your choice would be nice.

2)What brands/models/etc might you recommend for this system ?

3)Are there any companies (in the Chicago land area would be a plus, but not a necessity )that you might recommend that specialise in HVAC/Refrigeration control/monitoring installations ?


Thank you for your time. If you have any questions please ask, I will answer to the best of my ability.



..............................Blake

[Nihilist]

I would just like to clarify that while there is a budget, I am fairly aware of the costs associated with systems of this type. I only mentioned budget so that there was a clear understanding that there is a budget, and that I would like it to be as reasonable as possible.



Thanks.................Blake