PT100 sensor issues

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Matt in Birdham
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PT100 sensor issues

Post by Matt in Birdham » Mon Oct 19, 2015 9:55 am

I brewed for the first time in ages yesterday using my ghetto herms rig. This is controlled with an Auberins PID & PT100 sensor.
Halfway through the mash I got an "ORal" error and temp stopped reading - the unit switched off the heating element, but I think I got away with the mash.

I've had a fiddle with the sensor and connections this morning, and can't see any obvious issues with the connections. I unscrewed the sensor from the thermowell to take a look at that as well and - as far as I can see - that looks OK too. After re-connecting everything it starts with the error, but within about 10 seconds it starts reading the temp OK.

I wonder if anyone could help:

1. Have I stuffed the probe by opening up the thermowell? There seemed to be a little of resistance that gave as I pulled the sensor out (not all the way), and I am wondering if this was stuck in with some kind of thermal adhesive before. Temps still seem to read OK though, if perhaps a little high (maybe 1-2C - need more tests to confirm).

2. Are there any relatively easy checks I can do to try and isolate the problem (and hopefully fix it)? I must admit that I have already jumped on the Auberins site and ordered a replacement, but this will take a while to arrive and - being a bit impatient - I'm would like to try another brew in the mean time. I'm thinking that if it does stuff up again mid-mash I could put it on manual mode and measure the temp at the output with my thermapen, which should at least keep me in the ball-park.

thanks,
Matt

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Re: PT100 sensor issues

Post by aamcle » Mon Oct 19, 2015 10:41 am

I'd suggest getting a cheap pt100 from evilbay like the one in the link.

http://www.ebay.co.uk/itm/like/0-2-Clas ... RTM2108002

Use it to check and probably replace your current pt100, you will need to do the ice/boiling calibration.


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Re: PT100 sensor issues

Post by LeeH » Mon Oct 19, 2015 10:44 am

It should read 100 ohms at 0 degC. Around 110 at ambient. But I guess the probe is fine or the controller would have a permanent error displayed.

The error code will be in the controllers manual so that would be my first port of call.
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Re: PT100 sensor issues

Post by Wonkydonkey » Mon Oct 19, 2015 11:21 am

The oral means, as far as I know.... The sensor is not conected. So you have either a loose connection on the screws on the back of the pid, or a broken wire in the lead that the pid noticed as it lost its reading. And then shut down.

In the thermo-well there should be some sort of conducting paste that helps eliminate the gap and give a proper conducted reading, ie no air gap.

So like others have said get another pt100, and all should be fine. But you could recheck your pt100 and wiggle the wires a bit to see if you get the oral error again.

Edit; do you have spade conectors from the lead connecting to the pid ?

I think I would have checked all connections 1st then see if it sorts it, then see if I can make the error come back with the wiggling of any wires.

But that loose pt100 in the thermo well will now give erratic readings or slower readings as it moves /gets knock. So check/recalibrate and check again and again to see if you get stable readings
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Re: PT100 sensor issues

Post by themadhippy » Mon Oct 19, 2015 12:21 pm

its either an instruction to your partner or
8.1 Display orAL
This is an input error message. The possible reasons are: the sensor is not
connected correctly; the input setting is wrong type; or the sensor is defective.
In this case, the instrument terminates its control function automatically, and
the output value is fixed according to the parameter OUTL. If this happens
when using thermocouple sensor, you can short terminal 4 and 5 with a copper
wire. If the display shows ambient temperature, the thermocouple is defective.
If it still displays orAL, check the input setting, Sn, to make sure it is set to the
right thermocouple type. If the Sn setting is correct, the controller is defective.
For RTD sensors, check the input setting first because most controllers are
shipped with the input set for thermocouples. Then check the wiring. The two
red wires should be connected to terminals 3 and 4. The clear wire should be
connected to terminal 5
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Matt in Birdham
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Re: PT100 sensor issues

Post by Matt in Birdham » Mon Oct 19, 2015 12:55 pm

themadhippy wrote:its either an instruction to your partner or
Ah yes - I can see that going down well (so to speak) :)

Thanks for the replies guys. I have been playing with it this morning, unscrewing a few bits with nothing obvious wrong. It is now "working", which is in some ways the worst outcome, because I don't know what was wrong. I am guessing a connection at the probe end. No doubt I will end up convincing myself it's good to go and it will stuff up during another brew.. but I do have another probe & cable ordered (at vast expense from the US - but they are the only ones I can see that will fit my connectors), so hopefully that will fix the issue properly.

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Re: PT100 sensor issues

Post by Matt in Birdham » Mon Oct 19, 2015 12:59 pm

Wonkydonkey wrote:The oral means, as far as I know.... The sensor is not conected. So you have either a loose connection on the screws on the back of the pid, or a broken wire in the lead that the pid noticed as it lost its reading. And then shut down.

In the thermo-well there should be some sort of conducting paste that helps eliminate the gap and give a proper conducted reading, ie no air gap.

So like others have said get another pt100, and all should be fine. But you could recheck your pt100 and wiggle the wires a bit to see if you get the oral error again.

Edit; do you have spade conectors from the lead connecting to the pid ?

I think I would have checked all connections 1st then see if it sorts it, then see if I can make the error come back with the wiggling of any wires.

But that loose pt100 in the thermo well will now give erratic readings or slower readings as it moves /gets knock. So check/recalibrate and check again and again to see if you get stable readings
The connection is made via a cable with 3 pin connectors at each end - see the front connector on my control box here:

Image

The connection to the pid is done with spade connectors - you can't really see in the pic, but this is the inside of my control box:

Image

It is a little more "compact" in there than I would like, but such are the perils of ordering boxes on ebay. One day I'll re-house it but from what I can see all connections are sound.

Belter

Re: PT100 sensor issues

Post by Belter » Mon Oct 19, 2015 3:14 pm

They are really delicate. Sounds like you've tugged or bent it a bit too hard

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PT100 sensor issues

Post by LeeH » Mon Oct 19, 2015 6:01 pm

Matt, the photo isn't clear but I cannot see an earth on that metal enclosure.

If it hasn't I'd do it sooner rather then later. If it ever becomes 'live' you'll be getting a tingle.
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Matt in Birdham
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Re: PT100 sensor issues

Post by Matt in Birdham » Mon Oct 19, 2015 6:50 pm

LeeH wrote:Matt, the photo isn't clear but I cannot see an earth on that metal enclosure.

If it hasn't I'd do it sooner rather then later. If it ever becomes 'live' you'll be getting a tingle.
It is earthed with a ring connector screwed in to the base from the kettle lead "in" earth - you can't see it but it is under the kettle lead in/out combo on the right :) Also run through an RCD just in case, but the house also has one as well which is pretty sensitive (well - it cut out when I cut through the strimmer power cord last week 8) )

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Re: PT100 sensor issues

Post by Matt in Birdham » Tue Oct 27, 2015 9:54 pm

Update on this: I ordered replacement probe and cable from Auber which arrived today (great service, and no customs charge). Unfortunately this didn't fix the issue - which serves me right I suppose for ordering without really getting to the bottom of it.
Now I guess the issue is somewhere in the PID, but it is very hit and miss. I can run it for hours (have done tonight) with no issues, then it happens. Makes things really hard to test, but does seem to have association with length of run time (heat?) and turning on/off (which I do at mash-in).

I guess now the only option is replacement PID, but I don't fancy forking out for US postage again (will if I have to).
How are the UK ebay PIDS? Can anyone recommend a particular brand/seller? They are very cheap, but they look OK. Ideally something that is not going to crap out on me mid-mash..

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Re: PT100 sensor issues

Post by UpTheToon » Wed Oct 28, 2015 9:20 am

Matt in Birdham wrote:Update on this: I ordered replacement probe and cable from Auber which arrived today (great service, and no customs charge). Unfortunately this didn't fix the issue - which serves me right I suppose for ordering without really getting to the bottom of it.
Now I guess the issue is somewhere in the PID, but it is very hit and miss. I can run it for hours (have done tonight) with no issues, then it happens. Makes things really hard to test, but does seem to have association with length of run time (heat?) and turning on/off (which I do at mash-in).

I guess now the only option is replacement PID, but I don't fancy forking out for US postage again (will if I have to).
How are the UK ebay PIDS? Can anyone recommend a particular brand/seller? They are very cheap, but they look OK. Ideally something that is not going to crap out on me mid-mash..
I've been using a Sestos PID for around a year without issue. I've just looked at the link my amazon order and the model number is the same but it appears to have been rebranded to "inkbird".

http://www.amazon.co.uk/dp/B008GS2QFU/r ... 71_TE_item

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Re: PT100 sensor issues

Post by Matt in Birdham » Wed Oct 28, 2015 10:55 am

Thanks for the link. Interesting because it looks a bit different and others are still selling the sestos (on ebay, but only from China).
Might take the plunge.

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Re: PT100 sensor issues

Post by Matt in Birdham » Tue Nov 03, 2015 1:16 pm

Update on this:
With the new probe and cable not fixing the problem, I contacted Auber customer service and was surprised to get a very informative response within an hour. After a bit of back and forth it was suggested that I review my P, I and D settings as certain combinations can induce some unstability, and the result can be what I was seeing. I was sceptical (of course) since I hadn't seen this error in over 20 AG runs when I was still in Australia, but I ran the system again and got the error to happen after rising from 18-65C. At this point I changed the settings to the ones that the Auber support guy had provided and the system started working again. Not conclusive proof of course, but I have now run some sustained temps for a few hours and not had an issue. My settings were a little "weird" apparently (result of an autotune years ago). Also he picked up on the issue that my power cycle was set to 20s and should have been 2s for an SSR - this certainly has resulted in more rapid on/off of my HERMs element, and maybe it will be a little more accurate (it was pretty good before). I still don't understand why this issue would just start happening, but perhaps it is due to the change in brewing environment? Down-under I was typically brewing in 25-30C whereas my shed here has been in the 15C range. That's all I can think of.

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Re: PT100 sensor issues

Post by T5FAU » Tue Nov 03, 2015 2:23 pm

I dont know if this is related, but i had an earthing problem on my Auber PID, where the connectors i used (same as yours) were picking up interference from the chassis earth. Its turns out the PID was set for a 60Hz supply, not 50hz for the UK, see my other post:
viewtopic.php?f=6&t=29903&p=449133&hilit=50hz#p449133

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