We have a real application to use the Lab Note Taker addon. It was used to verify the accuracy of a DI-245 four-channel voltage and thermocouple data logger. The result can be found below.
What are involved
Fluke 515A Temperature/Pressure Calibrator, which is connected to the WinDaq-running PC via either a real COMM port or USB-based virtual COMM port.
DI-245 four-channel voltage and thermocouple data logger
Noble metal thermocouple wires from Omega include
SPPL (Platinum)
SP10RH (Platinum 10% Rhodium)
SP13RH (Platinum 13% Rhodium)
SP6RH (Platinum 6% Rhodium)
SP30RH (Platinum 30% Rhodium)
To construct S,B,R type thermocouples:
Type S: Platinum (-) vs Platinum 10% Rhodum (+)
Type R: Platinum (-) vs Platinum 13% Rhodum (+)
Type B: Platinum 6% Rhodum (-) vs Platinum 30% Rhodum (+)
N and E type thermocouple wires from Omega
Type N: TT-N-20-SLE
Type E: GG-E-24
Generic J, K and T thermocouple wires
Environment chamber for thermo-stability test
WinDaq acquisition software
Lab Note Taker addon
Configuration:
Maximum WinDaq sample rate is set to 200s/s
WinDaq Sample rate is set to 40s/s, average is turned on
Ambient temperature: 25C except the study of thermal offset drift inside the environment chamber
Minimum air flow
Sample script file for Lab Note Taker
TC_TYPE E<SKIP>
OPER<SKIP>
4<INTERVAL><SKIP>
OUT -160 CEL
OUT -150 CEL
OUT -140 CEL
OUT -130 CEL
OUT -120 CEL
OUT -110 CEL
OUT -100 CEL
OUT -90 CEL
....
OUT 880 CEL
OUT 890 CEL
OUT 900 CEL
OUT 910 CEL
OUT 920 CEL
OUT 930 CEL
OUT 940 CEL
OUT 950 CEL
OUT 960 CEL
OUT 970 CEL
OUT 980 CEL
OUT 990 CEL
Test Results
Voltage accuracy for all gains, single channel
Range Max Error Accuracy 50V 19mV 0.018% 25V 5mV 0.010% 10V 2.3mV 0.012% 5V 1.4mV 0.014% 2.5V 0.6mV 0.012% 1V 171uV 0.09% 0.5V 137uV 0.014% 250mV 60uV 0.012% 100mV 17uV 0.09% 50mV 13uV 0.013% 25mV 7uV 0.014% 10mV 15uV 0.026% + 10uV All ranges are well within the spec of 0.05%+10uV
Offset thermal drift, from 25C to 55C, channel shorted, range is set to 10mV
The offset was within 10uV throughout the temperature range
Test result in WinDaq file format
Thermocouple accuracy for all TC types, single channel
Even though most TC charts show spec for sub-zero temperature range, the common practice is to use only T type thermocouple for sub-zero temperature measurement, see this
Full test result in Excel spreadsheet (please see the discussion about Open-Thermocouple-Detection OTD circuit)
TC Type Range (C) Max Error (C) S <=400 7.7 (see OTD discussion) >400C 3.3 (see OTD discussion) R <=300 7.9 (see OTD discussion) >300 3.1 (see OTD discussion) B <=1000 5.4 (see OTD discussion) >1000 3.4 (see OTD discussion) N <=50 2.8 N >50 1 E spec range 0.9 J spec range 1.5 K spec range 1.8 T spec range 0.3 All TC measurements are well within the published spec
Thermocouple accuracy for all four channels, type E
Channel 1 Channel 2 Channel 3 Channel 4 Max Error (C) 0.42 0.33 0.43 0.68 The readings are well within the spec of 0.1% of span + 1
Thermocouple accuracy with and without Open-Thermocouple-Detection (OTD) option
DI-245 employs Open-Thermocouple-Detection, or TC Burnout Test, feature when thermocouple inputs are selected, and it helps to monitor the thermocouple connection, but this feature will affect the readings, especially in type SBR.
To demonstrate the difference, we conducted an accuracy test on a standard DI-245, using S-type thermocouple on all four channels, then OTD is removed and a comparison test was conducted to show the difference
Here is the side-by-side comparison of accuracy plotting with and without OTD, and you can see when OTD is removed, the reading is much much better
Last update: 10/03/18
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