i am doing a project for my last year at university, and i want to monitor the temperature and pressure of a boiler using a plc and display then on a terminal. how can i do this? can anyone help me?

 

I have the greatest respect for students, and I try to help them whenever I can. I am a supporter of technical education in the process automation field.

But Didier, this is stuff you are supposed to know if you are in your last year at University... and if you don't, you are supposed to know how to find out.

There are numerous books about how to do this very simple application and others using PLCs.

I would, if I couldn't get the information any other way, visit the Omega Engineering website and get their catalog, which will probably have a schematic for doing exactly this exercise.

But, of course, when you turn the project in, you will reference whose publication you got the drawings from, yes?

 

Hey, how is it going, the way it sounds you will need a temp. Transmitter that puts out a 4-20ma and a pressure transmitter that puts out a 4-20ma but if you don't hav the money pneumatic d.p cell with a P/I converter might be a little cheaper the temp you could use type k thermocouple but an rtd is alot better and accurate this should hook you up.

 

Many solutions do exist, but you may look into Eurotherm Controller 2704 with Wonderware could get you up and running in less than 4 hours.

 

hi. i am the from turkey. in these systems generally use labview programs if u learn this program combination of plc will be easy.

 

you first have two instruments (temperature and pressure transmitters) giving out 4-20mA standard signal in the desired calibrated range. you will connect these input signals to analog input card on the plc. then you need a analog output card or terminals on that plc and connect digital displays capable of receiving 4-20mA signal and converted to desired range on the display.

you will have to write a simple program on the plc
to achieve all this task.

 

Hi,

I suppose Your PLC can be extended with an analogue input card, if You don't know check with the vendor.

If You already has this AI module, You simply get two appropriate transmitters (temperature and pressure) and connect them to the AI card, using the 4-20 mA standard signal. Make sure the process connections to the boiler are done properly. Both to make sure You are measuring the values You are really interested in, and safetywise.

Did I miss something important here, or is this answer to what You are asking? Let me know, maybe I can help if there is something else

Jim

 

If you only want to monitor it, as against performing some control, why make it so complicated as using a plc. simply set up your measuring instruments with standard curent loop outputs to input into digital panel meters.

 

First of all, you must have temperature and pressure sensors installed on the said boiler at the outlet. Then you can send analog signal (for example) to your PLC as representation of those measurements. From there program your PLC and terminal to display the measured value.
Good luck!!!

 

Didier,

I do agree with "anonymous' that students
shd be able to do independent research
and not ask for handouts. But, I went to
the library and found solutions to my term
papers all the time. And I gave credit to
those old guys in the 1890's! Not too
different from the internet age.

But at the same time you may be the only kid
in the class that knows control.com!!!!!!!!!
Its a help center and many experienced PLC-ers
are using it every day to be fast with solutions
and get on with their work - we all prosper
from this place!

Mike.

 

Using transmitters with 4-20 mA output is one way. It's old fashioned. To make the project interesting to score good marks, I would consider something modern, that is FoundationT Fieldbus (FF). FF networking of the transmitters to a linking device, and then Ethernet to a PC with configuration tool, OPC server, and software. Check out www.smar.com and contact me on the address below if you like. If you really want to know what you are doing, check if you university library has the book "Fieldbuses for Process Control: Engineering, Operation, and Maintenance" (buy online in hardcopy or download immediately in softcopy): http://www.isa.org/fieldbuses If they don't, ask your librarian to get a few copies.

If you can't buy the book now, you can download chapter 1 (overview) for free in softcopy form. It's free, but you must register an account. If your email does not support this hyperlink feature correctly, please copy the entire link and paste it into your Internet browser. Mind the line wrap, make sure to get the complete path all the way to the 4585: http://www.isa.org/Template.cfm?Section=Shop_ISA&template=/Ecommerce/Product Display.cfm&ProductID=4585

Jonas Berge SMAR
===========
[email protected]
www.smar.com
Learn fieldbus at your own pace: www.isa.org/fieldbuses

 

I have installed many burners, and boilers in Europe and we always hardwired the temperature and pressure controls to a physical controller and not a software controller in the PLC for safety reasons. Even if you are only monitoring these parameters, I think the same applies. The PLC should only be used as a back up display. Check with your local regs for boilers.