Copyright 2013 Baker Hughes Company.
English–DPI
620G Instruction Manual | 145
Procedures (CH1): Cold Junction (TC Method) and CJ (Measure)
4. Check the calibration is correct:
a. Select the applicable TC mV (measure) or (source) via the Calibrator Task Menu.
b. Apply the necessary values:
TC mV (measure):
-
10, 0 (short circuit)
TC (mV): 10, 25, 50, 100
TC mV (source):
-
10, 0, 10, 25, 50, 100
5. Check the error is within limits. Refer to Table
12.12 Procedures (CH1): Cold Junction (TC Method) and CJ (Measure)
Note:
Do the TC mV (measure) calibration before the CJ (Cold Junction) calibration. The
conditions for CJ calibration are as follows:
•
Battery mode (with DC charger disconnected).
•
CH1 active (TC or TC mV).
•
CH2 set to “None”.
•
Burnout Detection off (in CH1 TC settings).
•
Use miniature TC connectors.
There are two methods of doing a cold junction test; the CJ (TC Method) is the preferred method.
Both procedures are described as follows:
12.12.1 Cold Junction (TC Method)
Do the procedure as follows:
1. Connect the applicable calibration equipment. Refer to Table
1.
2. Set the reference unit temperature: 0°C.
3. Let the equipment get to a stable temperature (minimum: 1
hour since the last power on).
4. Use the calibration menu (see Section
12.1) to do a one-point calibration for the CJ (TC
method) function.
5. Calculate the expected reading, using the known error in the thermocouple and reference
unit.
6. Check the calibration is correct:
a. Select the TC measure function via the Calibrator Task Menu.
b. Check the equipment gives a TC temperature that is the same as the temperature on
the reference unit ±
0.1°C (0.2°F) after correction for the known thermocouple and
reference unit error.
Table
12
-
14: TC mV (Measure or Source) Error Limits
Input or Output TC
(mV)
Calibrator Uncertainty TC (mV)
Permitted DPI
620 Genii Error TC (mV)
(Measure)
(Source)
(Measure)
(Source)
-
10
0.0036
0.00011
0.0085
0.0090
0
0.0036
0.00010
0.0080
0.0080
10
0.0036
0.00011
0.0085
0.0090
25
0.0036
0.00015
0.0091
0.0100
50
0.0037
0.00025
0.0100
0.0125
100
0.0040
0.00046
0.0125
0.0170
