P.I.D. as pyrometer?

O

oldwolf

Joined
Dec 29, 2002
Messages
617
Awhile back I asked if a pid could be used as a pyrometer and was told it could. OK I got it hooked to 110ac and the thermocouple wired in. Turned on the power on and it read 65 at the top, which I believe was ambient temp. Bottom read 800.
When I put the probe into the forge it went to EEEE which was over temp I believe. I can't get it to read ambient again.
The info on the unit is at http://tibetwalk.com/tmp/tmp/tmp/set620/set620.htm. but it all greek to me and I'm not greek. Help please.
 
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The link above does not work... What kind of PID do you have? I use a PID as a pyrometer all the time. Maybe I could help if you provided more info.

Eric
 
Don't knowwhy the link doesn't work. I can go there from my favorites. Sometimes it brings up a user/password page. Anyhow it's called a SET-620 Temp. Controller. Don't know anymore so I put up the url.
 
The top number is the current temperature (labeled "PV"?) and the bottom is the set temperature, what the PID controller would be trying to control to (labeled "SV"?)

If the thermocouple doesn't work at room temperature, you might need a new thermocouple. It shouldn't have broken the PID controller. You should look for a thermocouple with a high temperature range, like 1800 F or more. Might also want to get a protective sleeve for the thermocouple.
 
Did you tell the PID what type of thermocouple you are using. If you're using a "K" type, you'll probably have to tell it 'high' or 'low' as well and it should be 'high'
 
I don't think it's broken, just need to figure out how to program it. I'm using a K type thermocouple that's shielded. It just went "Out of Range" when I first put it in the forge.

That's the same info I have for the controller, but confusing to me. I'm not trying to do anything but measure the forge temp.

Right now the top red leds are saying PASS and bottom ones all 0000.
 
if you have the probe wired backwards it will go down insted of up when it gets hotter. and read an over temp.
 
Thank JT for that info. I'll try wiring it the other way although I understand if it didn't have a resistor it could be wired either way.
 
oldwolf said:
Thank JT for that info. I'll try wiring it the other way although I understand if it didn't have a resistor it could be wired either way.
Click to expand...

well when i connected mine i did not use a resistor and i connected it wrong and it did not work. i just swapped the wires and bam perfect.
 
I switched mine and it's reading ambient temp again. Hopefully it's OK. I'll test it tomorrow.

Many thanks to all that tried to help:D
 
The single line readout model of PID is the one that most folks use for a pyrometer. Using the dual line readout, your going to have to read the manual of your particular controller carefully. Depending on the model of controller, you may have to set the upper and lower limits in order for it to work correctly. In some models it won't matter, but with others the upper an lower limits must be set above/below the expected temps to get an accurate reading.

This is the single line readout version that I generally recommend for use as a pyrometer: http://cgi.ebay.com/Universal-Digital-PID-Temperature-Control-Controller_W0QQitemZ350213152433QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item518a549eb1&_trksid=p3286.c0.m14&_trkparms=65%3A1|66%3A2|39%3A1|240%3A1318|301%3A0|293%3A2|294%3A50

Using the dual line readout model is kind of a waste in a pyrometer situation.
 
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Thanks Ed, I may get that one if I can't figure out how to program this one. This one was so much cheaper than getting a pyrometer and I missed the one in your link on ebay where I found mine.

Just tested it on the forge and it indicates the Temp just fine. Lower #s don't seem to effect it.
 
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