Fluke 2635A, User Manual

Page: 199 / 268

Maintenance
Performance Tests
7
7-11
Note
If other than a T-type thermocouple is used, be sure that the instrument is
set up for the type of thermocouple used.
3. Reconnect power and switch the instrument ON.
4. Insert the thermocouple and a mercury thermometer in a room temperature bath.
Allow 20 minutes for thermal stabilization.
5. Select the temperature and T-type thermocouple function for channel 1.Press
M
.
6. The value displayed should be the temperature of the room temperature bath as
measured by the mercury thermometer (within tolerances given in Table 7-4, plus
any sensor inaccuracies.).
7. The Thermocouple Temperature Accuracy Test is complete. However, if you desire
to perform this test on any other Input Module channel (2 through 20), repeat steps 1
through 6, substituting the appropriate channel number.
Open Thermocouple Response Test
1. Switch OFF power to the instrument and disconnect all high voltage inputs.
2. Remove the Input Module from the rear of the instrument. Open the Input Module
and connect test leads to the H (high) and L (low) terminals of channel 1. Reinstall
the Input Module into the instrument.
Table 7-4. Performance Tests for Thermocouple Temperature Function (ITS-90)
Thermocouple Type Thermocouple Accuracy Specifications 1 Year
@ 18-28 Degrees C
J
±
0.40
°
C
K
±
0.44
°
C
N
±
0.53
°
C
E
±
0.38
°
C
T
±
0.45
°
C
1. Reconnect power and switch the instrument ON.
2. Connect the test leads from the Input Module to an 820 ohm resistor.
3. Select the temperature and T-type thermocouple function for channel 1.Press
M
.
4. The value displayed should approximate the ambient temperature.
5. Replace the 820 ohm resistor with a 4 kilohm resistor to simulate a high resistance or
open thermocouple.
6. Verify a reading of "otc".
7. The Open Thermocouple Response Test is complete. However, if you desire to
perform this test on any other Input Module channel (2 through 20), repeat steps 1
through 8, substituting the appropriate channel number.