Keithley 2015, Руководство по обслуживанию

Страница: 30 / 158

1-16 Performance Verification
Verifying temperature
Thermocouple temperature readings are derived from DC volts measurements. For that rea-
son, it is not necessary to independently verify the accuracy of temperature measurements. As
long as the DC volts function meets or exceed its specifications, temperature function accuracy
is automatically verified. However, temperature verification procedures are provided below for
those who wish to separately verify temperature accuracy.
1. Connect the DC voltage calibrator output terminals to the Model 2015 INPUT jacks
using low-thermal shielded connections. (Use 2-wire connections similar to those shown
in Figure 1-1.)
2. Configure the Model 2015 for °C units, type J temperature sensor, and 0°C simulated ref-
erence junction as follows:
A. Press SHIFT then SENSOR, and note the unit displays the temperature units:
UNITS: C. (If necessary, use the cursor and range keys to select °C units.)
B. Press ENTER. The unit then displays the thermocouple type: TYPE: J.
C. Select a type J temperature sensor, then press ENTER. The unit then displays the
reference junction type: JUNC: SIM.
D. Make certain that the simulated reference junction type is selected, then press
ENTER. The unit then displays the current simulated reference junction tempera-
ture: SIM: 023.
E. Using the cursor and range keys, set the reference junction temperature to 0°C, then
press ENTER to complete the temperature configuration process.
3. Select the temperature function by pressing the TEMP key.
4. Source each of the voltages summarized in Table 1-7, and verify that the tempera-
ture readings are within limits. Be sure to select the appropriate thermocouple type
for each group of readings. (See step 2 above.)
Table 1-7
Thermocouple temperature verification reading limits
Thermocouple
type Applied DC
voltage* Reading limits
(1 year, 18°C-28°C)
J
K
-7.659mV
0mV
42.280mV
-5.730mV
0mV
54.138mV
-190.6 to -189.4°C
-0.5 to +0.5°C
749.5 to 750.5°C
-190.6 to -189.4°C
-0.5 to +0.5°C
1349.2 to 1350.8°C
* Voltages shown are based on ITS-90 standard using 0°C reference
junction temperature. See text for procedure to set reference junction
temperature.