Temp control

Rees

Member
Join Date
Jul 2003
Posts
6
Hi,
I'm a total N00bie when it comes to this stuff so I was hoping someone here might be able to point me in the right direction.
Is it possible to design a heating unit whereby you could control temperatures in multiple locations(10 to 12) independantly.Each zone would have its own heat source(up to 150 watts) and a probe running back to the unit in which you could programme the temp for that particular zone independantly of the others.

cheers Rees............
 
Thanx Ant1,
Checked out the links but unfortunately couldnt find much suitable.
can anyone else help me out please?

cheers
 
It's also posible to programm everything in a PLC.

When you have 12 positions you have to have 12 analoge inputs and 12 outputs.
You also have to have something for interaction with the people, see the status of the heating elements, temp. settings and so on.
Also fault messages for wire detection would be nice afcourse.

I know that siemens has something nieuw. A terminal with CPU insite for there 300 series. You can also put remote I/O on it when you need more. But I think that there would be a basic unit that suits your purpose very well.
Also the costs would be resonable, the units start at 750 euro more or less. THe only thing that can make it expensive is the programma. When you do it yourself it's pretty cheap, but when you have to hire someone it will be more expensive afcourse.
 
Thanks randylud,
I am trying to find out what components I would need rather than purchasing a complete unit.

JvdV,
Thats more what Im after although I dont know where to start with regard to components.If I knew what was needed I would purchase and assemble myself.Would you know the components I would need eg:pLC,temp probes etc?

cheers
 
Rees,

I would have to know a little bit more about the aplication.
THings like:
-Temperature range
-What kid of temperature diviations are alowed, 0,1 degrees Celcius or more like 2-3 degrees Celcius.
-What kind of heating elements ?? 150 Watts you wrote, but what kind of voltage is allowed or what voltage do you want to use
-How big is the object where the 12 heating elements go in to.
-Is it one big lomp of metal or is it totally seperate.

For the HMI:
-What kind of information do you want on the screen. Totaly graficall or only text in a couple of lines each time
-Do you want a grafical part with let you see a line with the temperature in time. SO you can see what had happend the last few hours, minutes.
-Do you want to use different temperatures according to the process. So sometimes 100 degrees, next time 110 degrees.

When I have the above info I can give you more speciffic questions, or even better, anwsers.
 
First, you need to define what temperature range you're trying to hold and how closely you need to hold the temperature to the setpoint. What type of heat source are you going to use? Can you get away with just turning the heat off or on as the temperature rises and falls, or do you need continuous variation (analog)? How quickly does the system need to react to changes? How do you plan to allow the operator to establish the temperature setpoints?

The temperature range will define the types of sensors available to you, the method of heating will define the control hardware, and the level of precision will define the control strategy to use.
 
temperature controllers

There are a lot of ways to accomplish what you want to do depending on the variables you have. Check out Watlow's website. They have a variety of different controllers that might be what you're looking for.
 
Sorry I wasn't more clear earlier.
I'm after something that will enable me to conrol 6 to 8 "zones" independently.
The temp range would only be say 0 to 35C.Ideally a reduction in power to keep temps stable (as opposed to on/off)would be preferable as ceramic heat globes would be used for the heat source and this would give the globes a longer life.However if an on/off type setup would be cheaper to setup this would be ok as well.Temp deviations wouldnt be that critical a few degrees would be fine.
The heating side of things will be powered by 240V the controls could be any voltage I guess.
As far as relaying temps go I was thinking of a small LCD where I could call up say zone 1 or whatever and getting the temp in that zone to be shown on the screen.

Thanks for your input guys.

cheers
 
To maximize the life of the ceramic globes, you can set up a 'duty cycle' for the heaters, say 10 seconds. Then, to control the temperature, you keep the heaters on for a percentage of the cycle. When you need a higher temperature, you keep them on for a higher percentage of the cycle. To lower the temperature, reduce the percentage. That way, the heaters never completely cool down, and you minimize the thermal stresses that they see.

Check out Horner Electric's OCS product line, also sold by GE Fanuc. It's a PLC with a built-in operator interface. I think Siemens also offers a similar product as does Unitronics.
 
Last edited:
Thanks for the advice so far Guys.
I will check out all the links supplied and see if I can find something suitable.

cheers
 
When you want to know somewhat more about a solution with PLC and witch componants you can use please let us know.
It seems like a pretty need project.
 
Thanks JvdV,
I will try to explain what I am trying to achieve.
I am trying to control temps independently in 10 to 12 or more locations(zones).
* Each zone only needs a temp range from 0 to about 35C.
* I only need to create a "hot spot" in each of these zones.
* The area in which each heaters will be placed would only be 1800x600x600mm each which will all be within close proximity to each other.
* The heating method I will use will be ceramic bulbs 240V,150W.
* Temperature deviations are not critical,a few degrees either way would be fine.
* As far as information on the screen goes all I would need would be to read what the current temps are in each zone,as an example just to be able to call up zone 1 and see what the temp is.However having a graphical setup where I could see what has happened in the previous 12 hours or so would be a bonus.
* As far as different temps go I would also need to be able to vary them once in any given 24 hour period,as an example,12 hours @ 32C, 12 hours at 25C.

Basically if this is achievable I would need to know what parts I would need to build it.hope this is the info you were after.

cheers Rees
 
terrarium

I do this for a profession
What you need is some type of input or Pt100 sensors or thermowire
some type of output like small relays
some type of control, or for each compartment a separate control (expensive but always working.

Proposal:
use a WAGO plc
use for hmi a standard pc or laptop (you will have to use it only for changes and monitoring the rest of the day usable for other things.
the plc itself costs 250 euro
for each set you will need another 100 euro for input and output together.
look at www.wago.com system 75
This plc is modular so if you want more later time just buy it and put it on. change the program if needed.
the program is very simple and can be done by me without any cost, if i can deliver the system.
In a plc you can program nice on time and even weekends.
At home i am using simple timer blocks as they are cheap and time programmable.
in summer i put the time a little lower as temp is higher.
but hey i only have 2 lizards and some fish.
so the need for automation is not needed.

i also would make a alarm if one is out of limits.
for the rest i could talk very long about it.
 

Similar Topics

We have a small plastic parts oven (SP at 210F). It used to have an old bimetal temperature regulator. We are upgrading it using two temperature...
Replies
7
Views
1,498
Needing some help. I have a machine that was put in storage and has ended up in my lap. It had a 5/02 originally but the card was pulled and I...
Replies
3
Views
1,350
I'm tasked with replacing a process's temperature controllers (which feature PID autotuning) with PLC control. Do any PLCs feature PID autotune or...
Replies
33
Views
10,152
Hello I have DTC 1001 and DTC 2001 delta Temp control connected to together as one unit , and this unit connected to SS2 plc via Rs485 , My...
Replies
0
Views
1,022
We are currently running 3 point temp control of a kiln and recently had a thermocouple failure which caused issues with our heat up cycle. In...
Replies
8
Views
2,307
Back
Top Bottom