![background image](http://html1.mh-extra.com/html/omega/871a/871a_user-manual_737648011.webp)
Figure 4-2. Access to Calibration Adjustments
TABLE 4-3
CALIBRATION ADJUSTMENTS FOR MODEL 871A
4.3
CALIBRATION FOR MODEL 872A
4.3.1
Equipment Needed
1. DC voltage calibrator with ±0.01% of setting and ± 20 µV accuracy.
2. 100: 1 divider: 1.98 kilohm and 20 ohm wirewound resistors with 0.02%
ratio accuracy or better.
3. OMEGA TRC III Ice Point Reference Chamber or distilled water ice bath.
4. OMEGA type J TRP Reference Probe or make a thermocouple
transition junction (see paragraph 4.3.3).
4.3.2
Environmental Conditions
To meet all specifications, the conditions for calibration should be: an
ambient temperature of 23º ± 1ºC; relative humidity less than 80%.
4.3.3 Setup
1. To make a thermocouple transition junction, silver solder a piece of
copper wire to each (type J) thermocouple wire and insulate the
junction with a waterproof jacket.
2. Connect the thermocouple wires from the type J transition junction to
an OMEGA miniature connector SMP-J-M.
8
871
Calibrator
Trimmer
Desired
Step
Adjustment
Range
Setting (V)
Adjust
Reading
1
Input Offset Null
220ºC
0.0000
R109
00.0ºC
2
+ Gain (X1)
1370ºC
5.3039
R104
1320ºC
3
+ Gain (X10)
200ºC
0.6939
R105
170.0ºC
4
- Gain
200ºC
-0.1527
R103
-40.0ºC
5
ºF Offset
200ºF
0.000
R102
32.0ºF
Содержание 871A
Страница 21: ...SCHEMATIC MODEL 871A DIGITAL THERMOMETER 18 ...
Страница 22: ...SCHEMATIC MODEL 872A DIGITAL THERMOMETER 19 ...