Omega CL940A, User Manual

Page: 31 / 69

Service Information
4-17
Insulated container with lid for controlled
environment
Position accurate thermometer sensor in
middle of MTC 1 and 2 as shown above
Figure 13
15. Calculate the Lower and Upper limits: First add a factory determined offset of
0.06
°C to the “Standard” value, then add/subtract 0.11 °C from the result. For example:
the thermometer reading stabilized at 23.82 °C; add .06°C offset to get 23.88°C, then
determine the upper limit as 23.99°C (23.88 + 0.11), and the lower limit as 23.77°C (23.88
minus 0.11). The CJC values should be no greater than these limits.
(NOTE: The 0.11 °C
value is derived from the 0.15 °C specification minus the .04°C uncertainty of the
temperature measurement device.)
4.2.2 Alignment Procedure
Published temperature uncertainty values can only be achieved if the temperature of
UUT is known within 40mK. Customers performing CJC adjustments in their facility
will need to calculate their own uncertainty.
For best results, the instrument keypad is the only part of the instrument that should
be touched after the acclimation period inside the controlled environment. The
temperature sensor should not be touched.
1. This procedure shall be performed within environmental conditions of 23 ±1 °C
and 5% to 95% RH.
2. The unit under test (“UUT”) shall be acclimated to the Controlled Environment for
a minimum of four (4) hours. The customer supplied calibrated temperature
measurement device used for CAL 11 and CAL 12 below shall also be acclimated in
the same Controlled Environment simultaneously with the UUT.
3. The equipment listed in Appendix A is required to align the UUT to operate within
the expanded instrument uncertainties for mV values specified in Appendix B .
Customers performing CJC adjustments in their facility will need to calculate their
own CJC uncertainty.
4. Remove the UUT battery door housing to expose the alignment access hole.