From dc5562d3c0b8fc0d9d8799b21e040857f974dcde Mon Sep 17 00:00:00 2001 From: Robin Clark Date: Fri, 11 Mar 2011 09:36:51 +0000 Subject: [PATCH] Thermocouple comp --- fmmd_design_aide/fmmd_design_aide.tex | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/fmmd_design_aide/fmmd_design_aide.tex b/fmmd_design_aide/fmmd_design_aide.tex index 11bbcd1..899f981 100644 --- a/fmmd_design_aide/fmmd_design_aide.tex +++ b/fmmd_design_aide/fmmd_design_aide.tex @@ -569,4 +569,15 @@ DAH. The circuit is arguably safer now but statistically less reliable. +\paragraph{Practical side effect of checking for thermocouple disconnection} + +Because the potential divider provides an offset as a side effect of detecting a disconnection +resistance in the thermocopule extension or compensation cable will have an effect. +For a `k' type thermocouple this would be of the order of $5 { }^{o}C$ for $100\Omega$ of +cable loop impedance. Therefore, accuracy constraints and cable impedance should be considered +to determine specified maximum compensation/extension lengths. + + + +%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%