Hello Gabriel,
It is unfortunate that Foxboro doesn't give us more detail for the different
types of RTD options.
The temperature vs. resistance table for Laboratory Grade 100 Ohm RTD's with
Alpha 0.003925 starts at 0 deg. C and ends at 600 deg. C. I imagine this
would be the type of RTD that is used with SCI Option 42.
SCI Option 43 would be used with Alpha curve 0.00385 RTD's. It's
temperature vs. resistance table is from -200 to 600 deg. C. This Alpha
curve is specified by the US Standard ASTM 1137 and the IEC standard 751.
DIN 43760 should not ever be referred to anymore in that the standard is
obsolete.
SCI Option 44 is for SAMA RC21-4 1966 RTD's which are 98.1 Ohm RTD's with an
Alpha curve of 0.003923. It also has a temperature vs. resistance table
from -200 to 600 deg. C. The SAMA RC21-4 1966 standard is also obsolete.
If you have not specified a special RTD for your application it is quite
likely that you would want to be using option 43.
Regards,
Dan
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Dan Karppi CCST
Falconbridge Limited
Smelter Complex
Falconbridge, Ontario
Canada
P0M 1S0
Phone: (705) 693-2761 ext. 3881
Fax: (705) 699-3887
mailto:[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]
Sent: Wednesday, May 23, 2001 9:06 AM
To: Foxboro DCS Mail List
Subject: AIN block CSI 42.
We use DIN Platinum RTDs, so I gather the SCI in the AIN block should be
set to 42, but if I use this SCI, the block wont read negative temperature
values, so we have to use the IEC index of 43.
Can anybody throw light on this please ? Am I correct in my assumptions ?
What do others do in this situation ?
Regards,
Gabriel O'Dwyer,
Eli Lilly,
Ireland.
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