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Jumps in Temperature Data from PicoLog TC-08

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Jumps in Temperature Data from PicoLog TC-08

Postby cori.rose.schroer » Wed Jun 03, 2015 1:07 pm

Occasionally during data collection, jumps of about 6 or 7 degrees C occur in the data. The jumps occur instantly and within stable conditions and could be either increasing or decreasing in temperature. It can occur in only one probe, or all of them. It is also quite rare and occurs with different generations of thermocouples. Is there anything I could do to prevent these inconsistencies?
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Re: Jumps in Temperature Data from PicoLog TC-08

Postby Hitesh » Tue Jun 09, 2015 10:46 am

Hi cori.rose.schroer,

Are you using a desktop or laptop PC? If it is a laptop are you using mains or battery power?

Are the thermocouples touching any metallic or ceramic surfaces?

Regards,
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Re: Jumps in Temperature Data from PicoLog TC-08

Postby cori.rose.schroer » Tue Jun 09, 2015 12:51 pm

It has occurred on both a laptop and PC it only operates from usb power. It is monitoring temperatures of an AC-DC power supply and a printed circuit board. So yes.
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Re: Jumps in Temperature Data from PicoLog TC-08

Postby Martyn » Mon Jun 15, 2015 2:50 pm

I would suggest insulating the thermocouple tips, dipping in varnish will do, and also try using the laptop without the laptop power supply being connected.

Both of these suggestions will eliminate any potential ground loops.
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Re: Jumps in Temperature Data from PicoLog TC-08

Postby cori.rose.schroer » Mon Jun 15, 2015 2:53 pm

What type of Varnish do you suggest? Our tests are run for lengths of time longer than the battery would last on a laptop. Do you think the varnish would help enough by itself?
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Re: Jumps in Temperature Data from PicoLog TC-08

Postby Martyn » Mon Jun 15, 2015 3:04 pm

It is not something I have done myself so don't have a specific type, clear varnish is what others have tried. This may work on it's own.

Trying the laptop on battery would be a quick test to see if resolves the issue, not a long term logging solution. If it does prevent the jumps then the supply may inducing some noise, or that it is grounded, so a different supply may be better.

The other issue could be that the thermocouple wires are picking up noise from the circuit under test so consider rerouting the wires.

It is often a case of trying different solutions to work out which one is the correct option in your situation.
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Re: Jumps in Temperature Data from PicoLog TC-08

Postby cori.rose.schroer » Mon Jun 15, 2015 3:14 pm

thank you.
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