VT regulation problem

From: Jan Lang (Jan.Lang@vscht.cz)
Date: Tue Mar 01 2005 - 08:33:17 PST


Dear BUMers,
We have a problem with stabilisation of temperature using BVT 3000 on Bruker
Avance 500 system.
It was working nicely about 8 years.
The problem is:
Arrival to the temperature set in "edte" has become very slow. Usually,
"self-tuning" the feedback loop fixed this in the past, but it does not help
now, no matter what actual temperature is set.
In addition, in the medium-run (say minutes), we see +-0.1 K fluctuation of
sample temperature and accompanied variations in heater current.
We see the problem on two probes with different thermocouples (T and
BTO2000), so it is not related a particular thermocouple nor to the wire
connecting the thermocouple and the BVT.
To me, it is seems rather as a sofware problem, that the "self-tune" routine
does not work properly or the BVT unit does not accept the results.
Did anybody observe anything similar? And better, does anybody knows the
solution?

Best regards,

Jan Lang

Institute of Chemical Technology
Prague, Czech Rep.

Some technical details from edte:
Edte release 98324.B7
Eurotherm 902
Eurotherm software 0.1.04
Mainboard hardware 0.3
Mainboard software 2.7



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