Rtd pt100

[wizdumb1]

Hi,

I am slowly getting the parts together to build an electric brewery. I ordered two RTD PT100 from china to try to save a little. Like $30 something on Aubers. I paid like $12 each for them but I'm not sure if they will work. I only see two pins and the other two holes are sealed. There are 3 wires though. Will this still work? I am using two Inkbird ITC-106VH

 

[augiedoggy]

Hi,

I am slowly getting the parts together to build an electric brewery. I ordered two RTD PT100 from china to try to save a little. Like $30 something on Aubers. I paid like $12 each for them but I'm not sure if they will work. I only see two pins and the other two holes are sealed. There are 3 wires though. Will this still work? I am using two Inkbird ITC-106VH

I'm going to assume the actual outside of the connector is carrying the path of the third wire..(easy enough to test with a meter or tester for continuity).

The similiar $12 pt100s I just bought has 4 pins but only 3 being utilized. If the manufacturer used the 3 pin connectors they would be 100% the same as the ones they appear to currently supply to auberins which I doubt auber would be thrilled about. I've seen these side by side and they are indentical besides having g the 2 or 4 pin connectors vs the 3 pin auber carries.

 

[EnglishAndy]

I'm going to assume the actual outside of the connector is carrying the path of the third wire..(easy enough to test with a meter or tester for continuity).

It isn't. Well, if it is then it's broken.

The two wires coded the same color are connected together at the same end of the PT100 element and the unique colored wire is connected to the other end.

The measuring device sends a small excitation current across the element and uses the voltage drop to calculate the resistance of the element plus the leads. It then does the same across the two leads connected to the same end of the element and uses the result to cancel out lead resistance.

I have several of these Chinese probes. They seem to work but vary wildly in their accuracy and will need calibrating against a reference before use. I haven't measured linearity or drift over time. RTDs should hold their calibration for a long time but since you can't see inside these probes you don't know if the element is actually platinum, which is not cheap and believe me the Chinese will fake _anything_ if they can to make a few cents.

I did some testing of the cheaper probes in my own dual-RTD board design here.

 

[augiedoggy]

It isn't. Well, if it is then it's broken.

The two wires coded the same color are connected together at the same end of the PT100 element and the unique colored wire is connected to the other end.

The measuring device sends a small excitation current across the element and uses the voltage drop to calculate the resistance of the element plus the leads. It then does the same across the two leads connected to the same end of the element and uses the result to cancel out lead resistance.

I have several of these Chinese probes. They seem to work but vary wildly in their accuracy and will need calibrating against a reference before use. I haven't measured linearity or drift over time. RTDs should hold their calibration for a long time but since you can't see inside these probes you don't know if the element is actually platinum, which is not cheap and believe me the Chinese will fake _anything_ if they can to make a few cents.

I did some testing of the cheaper probes in my own dual-RTD board design here.

Do you have this exact one? the two identical colored wires could be on the 2 pins right or no? im aware they are both connected together at the probe end and they are for greater accuracy.

Do you have any of the ones auber sells because they appear to me to be identical chinese probes..(I even found the same ones with aubers pics auber uses on alibaba a couple years ago in 304 or 316 stainless from the supplier.) they disappeared shortly after I pointed them out to brau supply when he claimed he was the only one who had 316 probes made especially for him to sell).
I dont doubt what your saying but all of the pt100 probes I bought from china (quite a few now, id have to say about 10 total of different types) all have 3 wires and at least three pins. one of them was poor quality and was not accurate (also rusted).

Currently I have a few of these,

https://www.ebay.com/itm/rtd-pt100-...824983&hash=item1c8fd507e5:g:LTMAAOSwgGdZpC3v

and 2 of these (4 pin)
https://www.ebay.com/itm/RTD-Pt100-...e=STRK:MEBIDX:IT&_trksid=p2057872.m2749.l2649

and 2 of these which are my favorite with the better teflon coated cable.

https://www.ebay.com/itm/RTD-PT100-...431862?hash=item28339a24f6:g:59QAAOSwaZdZv08r

I have had no calibration issues with mine thus far. the last 2 have been in use for about 4 years now replacing the older cheaper non detachable type which would catch on things and short out.

 

[EnglishAndy]

Do you have this exact one? the two identical colored wires could be on the 2 pins right or no? im aware they are both connected together at the probe end and they are for greater accuracy.

I have one that looks an awful lot like your first link and two that look like this. I bought these cheap ones to verify that my board design worked before splashing out on a 'real', i.e. traceable source probe to use for real.

Do you have any of the ones auber sells because they appear to me to be identical chinese probes..(I even found the same ones with aubers pics auber uses on alibaba a couple years ago in 304 or 316 stainless from the supplier.) they disappeared shortly after I pointed them out to brau supply when he claimed he was the only one who had 316 probes made especially for him to sell).

No I don't have any of those. I'd expect the cost of getting an exclusive design produced just for one small seller to be very high. I'd treat his claim as suspect.

I dont doubt what your saying but all of the pt100 probes I bought from china (quite a few now, id have to say about 10 total of different types) all have 3 wires and at least three pins. one of them was poor quality and was not accurate (also rusted).

3 wire is the most commonly used. 2 wire isn't accurate enough unless the leads are extremely short and the additional accuracy of 4-wire (cancelling out lead-length mismatch) just isn't worth it.

All 3 of mine from China were off by varying amounts but once I applied a calibration offset they appeared not to drift, at least in the short term. Only the good quality probe that I bought locally was spot on. If you have a multimeter that's known to be accurate to a few 10s of milliohms you can perform the measurements yourself and check them off against a lookup table.

 

[frodus17]

Can you take apart the plug?

One wire (red) is one side of the Thermistor. The two blue wires are connected to the other side of the thermistor. What it's for, is for lead compensation, so it knows the resistance of the cables. Since there's only 2 wires, I'd open that plug to see if there's 3 wires. If not, just connect RED and BLUE to the ITC, and bridge the Blue lead over to the other Blue terminal.