Panel Mount RTD connectors

[Walker]

Does anyone know how sensitive the RTDs are? Meaning, will running them through some random connector mess up their accuracy?

I need to get a panel mount connector for the RTD in my HERMS, and really don't want to buy the one from Auber unless I have to because I know I'll be overpaying for it.

I just don't know enough yet to select a suitable/identical yet less expensive connector from somewhere like mouser.com or even ebay.

Is there anything special about the connector?

 

[Fletch]

Any good quality discrete connector with 3 (or more) contacts would work ok. You just want to avoid any resistance through the connector, as of course that would throw off your sensed temp. Thermocouples are a different matter, and the proper, type-specific connector MUST be used. McMaster has male and female for about $14 a pair, but I didn't find a panel mount RTD female.

 

[Boerderij_Kabouter]

What are you finding cheaper than the $3.50 or whatever Auber charges?

 

[Walker]

What are you finding cheaper than the $3.50 or whatever Auber charges?

Well, like I said, I haven't started looking yet because I didn't know what to look for at this point.

My comment about over paying is just based on the other items I have purchased for my HERMS system (PID, SSRs, heatsinks, 4" RTD, and definite purpose contactors). Looking around and buying them from various sources has saved me a considerable amount of money vs. buying from Auber.

 

[diatonic]

The thing that's nice about the ones at Auber is that it is the same type of connector as on the RTD as well. They are small, simple, and work great. I got mine as part of a larger order so the shipping was negligible.

 

[Walker]

Even ignoring shipping, auber's prices are high on many things, IMO.

It would have certianly been easier and more convenient to just order everything from them and not spend time searching around, but I was in no rush with purchasing, so I opted for the savings.

I've got no problem ordering from them if they have a good price, I was just wondering what it was that I needed to look for in order to shop around. It sounds like low resistance is really the thing of concern with an RTD.

I'll poke around a little to see what's out there.

edit: I am not trying to bash Auber. Sorry if it came across like that (and re-reading my first post, I can see how it might have seemed that way). I just want to shop around based on previous price comparisons I have done.

 

[Boerderij_Kabouter]

In that case you are correct. You just need low resistance that is all. RTDs work on a resistance difference at the probe, the wires just need to accurately transmit electricity from the probe.

 

[Walker]

Would one of you that has one of them mind measuring the reistance of it, just to give me a ballpark figure?

I'm seeing 3-wire connectors that measure less than 20 miliOhm @ mouser.

On a somewhat related topic...

The manual for my PID and a few posts on here talks about how to connect the RTD and mention 2 red wires and 1 white wire, but my RTD has 1 red, 1 blue, and 1 yellow.

I found a couple of ways to connect the 3 wires of the RTD and get what looks like a correct temp reading, but has anyone else seen an RTD with the three colors like mine has?

 

[klyph]

If you calibrate it with the connection in place, what does the resistance matter?

 

[jkarp]

Auber's support is phenomenal. Every question I've e-mailed - even on weekends - has been answered w/in an hour. I'll give 'em a little slack in the price dept. for that.

 

[Walker]

If you calibrate it with the connection in place, what does the resistance matter?

I think the calibration of a probe on a PID just allows you to set a static offset value in degrees. That might work, but wouldn't that rely on a linear resistance curve for the RTD?

Meaning, a 1 Ohm added resistance from the connector might be equal to 1*F degree in ice water, but that 1 Ohm at 150*F might be equal to more or less than 1*F.

or am I over thinking things?

 

[klyph]

You could be right, but it would be easy enough to test.

Add a resistor to the probe, test in ice water and boiling water, compare to readings without resistor...

 

[Walker]

Maybe I'll just make some beer and stop thinking about all of this.

 

[lspr_mtu]

Auber's support is phenomenal. Every question I've e-mailed - even on weekends - has been answered w/in an hour. I'll give 'em a little slack in the price dept. for that.

Agreed. I got confused one day on the PID v PID w/SRR v w/contact... I called them up, said it was for beer, and the guy basically said "dude, this is what you want"...

It was very refreshing.

 

[CodeRage]

RTDs put out a (for our purposes) 100ohm to 138ohm resistance range of 0 to 212F. thats .18ohms per degree. Using that as a reference you can figure out a given connectors resistance will affect the temp reading.

Depending on the circuit used to measure the RTD, a line resistance compensation circuit can be added to subtract the additional resistance. This is why some RTDs come in 3 to 5 wire configurations. You couldn't do this with just 2.

Unless the documentation says it compensates, if it has more than 2 terminals to connect the RTD it more than likely does.

 

[ILOVEBEER]

What are you finding cheaper than the $3.50 or whatever Auber charges?

DITTO-

I use one. I purchased everything from Aubers and SUYI (owner) walked me through the setup and everything.....

 

[Ohio-Ed]

I've used theses small microphone jacks when I didn't want to wait... but cheaper... don't think so?

http://www.radioshack.com/product/index.jsp?productId=2103996

 

[ILOVEBEER]

The awesome thing about Aubers quick disconnect is just that...it is a quick disconnect (like an air fitting). I will never buy from another vendor..I am sold on his customer service and pricing!

 

[paledragon]

i used the same ones as ohio-ed. i had planned on going with XLR audio connectors, but just happened to come across these while at radio shack.

p.d.

 

[Sawdustguy]

Jason (CodeRage) is correct. If you are concearned about the extra resistance buy a four wire RTD. If works similarly to the sense lines on a DC power supply which compensates for any extra resistance in the leads or another example would be the 4 wire ohms measurement on a multimeter.

 

[illin8]

I bought the Panel Mount connector for RTD sensor from Auber but haven't used it yet. If I were to clip the RTD wires and put this in line for a quick connect, how would one go about making the connections? solder? which posts are which?

 

[Boerderij_Kabouter]

Solder. The posts don't mater as long as the transmitting stays consistent from sensor to input post (e.g., on you PID). I used pin 1 for white and pins 2/3 for the red wires.

 

[Walker]

So, I went ahead and ordered the connector fro Auber last weekend and it arrived in just a couple of days. I was under the impression that it came with the "inside the box" wiring included, but it didn't. Just the male and female parts.

So, I went to Lowe's to see if they had some suitable thin wiring to use and it looked like CAT5 cable was most suitable. I've got a box of unused ethetnet cables at home, so I didn't buy anything and just left.

But, on the ride baclk to my office I had a "Doh!" Moment. CAT-5. Of course!

I've not only got cables lying unused, but also a couple of wall plates I didn't need that came with a DSL modem.

8 wires in that cable. Enough for 2 RTDs in a single cable that would easily 'snick' into the connector and stay put.

I'm not going to use this since I already have the Auber connector, but if I ever build another system...

 

[CodeRage]

minute amounts of resistance can have a detrimental affect on an RTD reading. I would rather have a pin connector versus a spring and contact personally. Not saying it wouldn't work, just that I wouldn't use it

 

[Walker]

I agree that if the connector isn't suitable, then it isn't suitable. The thing is, I don't know how much resistance is seen through a cat5 connector *or* my auber connector. For all I know, they are on par with one another.

If I feel motivated, I'll measure them both tomorrow, just for grins.

I will say that, with out ANY connector in the path, my RTD had a 3.2*F error (checked in crushed ice water and boiling water), which I had to offset with the PID settings.

 

[BrewBeemer]

I used RC model airplane gold coated pin connectors, resistance was down to below the meter could read, this on a Fluke 87 not 88 which can read down to 0.01 ohms. Dissimilar metal contact alone at the connector would throw your low resistance probe readings off. With BCS controlled units they require 10K ohm probes, jacks or audio connections would be not a problem with their small added resistance vs 10K ohms in ratio on temp readings.

 

[kladue]

One feature of 3 and 4 wire RTD circuits is the paralelled connections( 2 red wires, or 2 white wires) are used to cancel the resitance effect of extended field wiring and connectors, in the measuring circuitry by making paralelled wires part of a wheatstone bridge.

 

[BrewBeemer]

Thanks Keven as I was wondering why the reason for 4 wire this explains it.
Now back to work. LOL!

 

[Walker]

One feature of 3 and 4 wire RTD circuits is the paralelled connections( 2 red wires, or 2 white wires) are used to cancel the resitance effect of extended field wiring and connectors, in the measuring circuitry by making paralelled wires part of a wheatstone bridge.

Ok, I thought I had read this before, but wasn't sure if I was making imagining it or not.

So... given that I have a 3-wire RTD (and leads that are under 6 feet long), it sounds like the connector isn't very critical.

Thanks, kladue.

 

[kladue]

In the industrial instrumentation field we can run up to 1,000+ feet of sheilded wire to 4 wire RTD's, the largest problem is electrical noise pickup not resistance in long runs.