|
|
Testing and Benchmarking Discuss, design, and debate ways to evaluate the performace of he goods out there. |
Thread Tools |
02-26-2006, 07:29 AM | #26 |
CoolingWorks Tech Guy Formerly "Unregistered"
Join Date: Dec 2000
Location: Posts: 2,371.493,106
Posts: 4,440
|
Re: sensor calibration
and that is exactly how it is done, yes Brian
the calibrating inst, the reference std, has a 10 fold greater accuracy (typically); all eventually traceable back to etc. precisely why I paid $900 for the 2804A, just following normal practice no cheap zeros (other than BSing) |
03-21-2006, 08:47 PM | #27 |
Responsible for 2%
of all the posts here. Join Date: May 2002
Location: Texas, U.S.A.
Posts: 8,302
|
Re: sensor calibration
A bump, because I'm heavily into calibrating my temp transmitters.
The unit: Moore Industries Temperature transmitter model RIY/PRG/4-20MA/12-24DC Specifications Manual (great little DIN rail mounted units, I got three, and there are still some available on eBay). These can be configured for a single RTD (2, 3 or 4 wire) or differential RTD (3 and 2 wires, or 2 and 2 wire). The LCD display is useless, for my purposes (only shows whole numbers). The output is a 4-20 mA, through the power supply line. The calibration procedure calls for a "250 ohm precicion resistor, 0.01%" and a decade resistance box, also 0.01%. I'll be trying to replace the box with only the precision resistors that are needed, if I can. As for the 250 ohm resistor, I figure that it only needs to be a known resistor, and doesn't actually need to be of 250 ohm (but should be at least that much). The resistance values for an RTD are listed here: http://www.omega.com/temperature/Z/pdf/z252-254.pdf (NOTE: these are for a 100 Ohm RTD, with an alpha curve of 0.003850, aka European curve) The units are set at the "zero" and "span" points (i.e. 0% and 100% of full scale). the settings are eeprom'ed. I'll try to contact the manufacturer, to get a copy of the linearization curve report. For reference, all three units are set as follows: Zero: -185 Span: 131 (I have no idea what these numbers represent) Input: 100 Ohm RTD, alpha 385, range -200 to 850 deg C, accuracy +/- 0.05% of span, +/- 0.20 deg C I've been going over Groth's frying pan method. I expect I'll be putting my Fluke 8840As to work, along with the voltage reference chips. |
03-21-2006, 09:07 PM | #28 |
Responsible for 2%
of all the posts here. Join Date: May 2002
Location: Texas, U.S.A.
Posts: 8,302
|
Re: sensor calibration
Hum... that table is pretty useless. Will have to figure out the actual calculation.
The meter shop: http://www.metershop.com/ |
04-27-2006, 02:23 PM | #29 |
Cooling Neophyte
Join Date: Sep 2001
Location: High Altitude Lab
Posts: 94
|
Re: sensor calibration
hey Bill, any pointers on how I might use and verify this?
looks like a calibration standard (might be that type printed on it ) and came from Micro Components Technology of course there isn't any reference to such a minor little device on the site those are DB15 connectors on each end and there are just old calibration stickers on the other side National Cal & Stds LAB (NIST affiliate? some other country's standards lab?) tag # date (94), due date (95), and D.B.S./CO134 52 AAA whatever that means Id like to first try to "use" it then see about getting it recalibrated
__________________
LurkyLoo Last edited by Ice Czar; 04-27-2006 at 03:52 PM. |
04-27-2006, 05:14 PM | #30 |
Pro/Staff
Join Date: Oct 2001
Location: Klamath Falls, OR
Posts: 1,439
|
Re: sensor calibration
I believe Bill is no longer posting on these boards (his own choice, he was not banned). You must contact Bill via email or other method.
|
04-27-2006, 07:42 PM | #31 | |
Cooling Neophyte
Join Date: Sep 2001
Location: High Altitude Lab
Posts: 94
|
Re: sensor calibration
Quote:
thanx
__________________
LurkyLoo Last edited by Ice Czar; 04-27-2006 at 07:55 PM. |
|
04-28-2006, 12:45 PM | #32 |
Pro/Staff
Join Date: Oct 2001
Location: Klamath Falls, OR
Posts: 1,439
|
Re: sensor calibration
Because Bill is so old that he actually might know semaphore signalling?
|
04-28-2006, 04:38 PM | #33 |
Cooling Neophyte
Join Date: Sep 2001
Location: High Altitude Lab
Posts: 94
|
Re: sensor calibration
well that and he has a thing for native american flag girls
__________________
LurkyLoo |
Currently Active Users Viewing This Thread: 1 (0 members and 1 guests) | |
|
|