The Great Bottle Opener Giveaway

Home Brew Forums > Home Brewing Beer > Electric Brewing > Thermocouple plug

Reply
 
LinkBack Thread Tools
Old 02-05-2013, 02:22 PM   #11
MagooBrew
Feedback Score: 0 reviews
Recipes 
 
Join Date: Dec 2012
Posts: 895
Liked 45 Times on 36 Posts

Default

Go to omega.com they sell t/c diconnects for panel mount for just a few dollars. These are made for this purpose. I have always had good luck with their products.

__________________

"A flute with no holes is not a flute......
....... and a doughnut with no hole is a Danish."

Ty Webb

MagooBrew is offline
 
Reply With Quote Quick reply to this message
Old 02-05-2013, 10:15 PM   #12
DougK
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
DougK's Avatar
Recipes 
 
Join Date: Jan 2013
Posts: 1,154
Liked 125 Times on 100 Posts
Likes Given: 1

Default

Quote:
Originally Posted by pentiumone133 View Post
I was thinking about this more, and if the issue is different types of metals creating a reaction and throwing off the temperature then how is it possible to connect the thermocouple to the PID at all? The wires crimp onto lug connectors. These lugs, I assume, are standard lugs not made out of specific material. Then, the lugs are screwed onto metal screws on the PID, which, again I assume are not made out of specifica materials. THEN....inside the PID there is traces and connections on the boards before it actually gets to its final destination in the logic, right?

How does this work? Its the same concept as cutting the cable in the middle and soldering in a copper wire. The metal type changes two or three times already between the sensor itself and the inside of the PID.
Depending on the unit, it will either have an internal temperature probe that they use to correct for the cold junction, or it will apply a constant correction and assume the controller will always be the same temperature. They may also ignore this transition, and assume the voltage is correct.

The cold junction is where you normally transition from thermocouple to copper. Normally 0 degrees c is used for this reference. If the cold junction occurs at 70 degrees c and is not corrected, the reading is going to be of by about one degree. For some applications, this amount of inaccuracy may be acceptable.

I'm an engineer in the aero industry, and our industry accuracy requirements are just a little more strict. I'm used to dealing with systems that have a 0.25 degrees of accuracy or less. I doubt you really need greater accuracy for brewing, however my experience in brewing is still pretty low.

Might just be a case of analysis paralysis. I'm thinking about it too hard and approaching it from the thought that any inaccuracy is unacceptable.
__________________

I'm not insane, my mother had me tested.

DougK is offline
 
Reply With Quote Quick reply to this message
Old 02-05-2013, 10:16 PM   #13
DougK
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
DougK's Avatar
Recipes 
 
Join Date: Jan 2013
Posts: 1,154
Liked 125 Times on 100 Posts
Likes Given: 1

Default

Quote:
Originally Posted by MagooBrew View Post
Go to omega.com they sell t/c diconnects for panel mount for just a few dollars. These are made for this purpose. I have always had good luck with their products.
Plus you get free Dilbert comics with every order.

I also get a kick out of their packaging tape.
__________________

I'm not insane, my mother had me tested.

DougK is offline
 
Reply With Quote Quick reply to this message
Old 02-05-2013, 11:33 PM   #14
whoaru99
Feedback Score: 0 reviews
Recipes 
 
Join Date: Oct 2012
Posts: 1,585
Liked 124 Times on 101 Posts
Likes Given: 16

Default

I run type K TCs and often use extensions to get from various parts of machines to a data acquistion unit. Most of my supplies are ordered from Omega, including the TC mini-plug connectors and the TC extension wire. There seems to be effectively no change when running these extensions over lengths of 20-25 feet, give or take. Have not tried longer as there is no point for my use, but I suppose I could put a jack and plug on the ends of a spool of TC wire and see what happens.

__________________

Primary: Edwort's Apfelwein
Secondary: Russian Imperial Stout
Drinking: Chinook IPA
Drinking: Waldo Lake Amber
Drinking: Edwort's Apfelwein

whoaru99 is offline
 
Reply With Quote Quick reply to this message
Old 02-06-2013, 07:36 PM   #15
pentiumone133
Feedback Score: 0 reviews
Recipes 
 
Join Date: Nov 2012
Posts: 58
Liked 5 Times on 3 Posts

Default

Can you guys show me what you mean by these plugs and jacks that you are using? everything on this site is completely different looking to me, having a hard time finding what I should be using that isnt super overkill.

__________________
pentiumone133 is offline
 
Reply With Quote Quick reply to this message
Old 02-06-2013, 09:28 PM   #16
DougK
HBT_SUPPORTER.png
Feedback Score: 0 reviews
 
DougK's Avatar
Recipes 
 
Join Date: Jan 2013
Posts: 1,154
Liked 125 Times on 100 Posts
Likes Given: 1

Default

mpj-k-f for a mini panel jack for use with type k thermocouple.

Nmp-k-m for a mini plug for type K thermocouple

Then you don't have to worry about any extra cold junctions.

__________________

I'm not insane, my mother had me tested.

DougK is offline
 
Reply With Quote Quick reply to this message
Old 02-06-2013, 09:46 PM   #17
passedpawn
Moderator
HBT_MODERATOR.png
Feedback Score: 0 reviews
 
passedpawn's Avatar
Recipes 
 
Join Date: Apr 2009
Location: ☼ Clearwater, FL ☼
Posts: 18,058
Liked 2939 Times on 1866 Posts
Likes Given: 2482

Default

Quote:
Originally Posted by DougK View Post
Depending on the unit, it will either have an internal temperature probe that they use to correct for the cold junction, or it will apply a constant correction and assume the controller will always be the same temperature. They may also ignore this transition, and assume the voltage is correct.

The cold junction is where you normally transition from thermocouple to copper. Normally 0 degrees c is used for this reference. If the cold junction occurs at 70 degrees c and is not corrected, the reading is going to be of by about one degree. For some applications, this amount of inaccuracy may be acceptable.

I'm an engineer in the aero industry, and our industry accuracy requirements are just a little more strict. I'm used to dealing with systems that have a 0.25 degrees of accuracy or less. I doubt you really need greater accuracy for brewing, however my experience in brewing is still pretty low.

Might just be a case of analysis paralysis. I'm thinking about it too hard and approaching it from the thought that any inaccuracy is unacceptable.
The problem is bigger than you might think. The Auber PIDs have a reference diode to attempt to correct for the temp of the cold junction. The cold junction is assumed to be at the back of the PID, so the reference is placed near the vent holes (you can actually see a leaded diode there). This works fine unless the temp at the reference diode is much different than the temp at the cold junction.

You can alleviate the problem by using thermocouple wire from the correct thermocoulple socket back to the PID. In my case, I also have a switch to select which TC my PID is looking at, so the switch became the cold junction even though I had the correct wire.

So, if you move the cold junction to, say, the outside of the control panel, then you might have a problem when the inside of the control panel starts to heat up.

So, the moral of the story is, if you can keep the back of the PID about the same temperature as your thermocouple plug, wherever that is, you'll be OK. If not, i.e., if you the back of your PID is near a hot SSR, you'll see several degrees of inaccuracy as the box heats up. Ask me how I know this.

BTW, I got a dual yellow TC plug on mcmaster carr. Here http://www.mcmaster.com/#thermocoupl...ectors/=ld62bi

__________________
a mote of dust, suspended on a sunbeam
passedpawn is offline
 
Reply With Quote Quick reply to this message
Reply


Quick Reply
Message:
Options
Thread Tools


Similar Threads
Thread Thread Starter Forum Replies Last Post
Where to Buy Thermocouple or RTD? RonRock DIY Projects 25 01-31-2013 02:10 AM
Tet-612 thermocouple help! ftlstrings Electric Brewing 11 01-20-2013 08:31 PM
tank plug gas vs tank plug liquid JLivermore Beginners Beer Brewing Forum 6 12-09-2012 12:26 AM
Which thermocouple to use? kburden1 Electric Brewing 6 10-26-2012 06:42 PM
Thermocouple or thermocouple wire source? e lo Equipment/Sanitation 22 11-08-2007 08:09 PM