Omega CL27 - Manual (Page 30)

B. RESISTANCE CALIBRATION
NOTE: Thermocouple and resistance calibrations are indepen-
dent. However, potentiometer P1 is used in both thermocouple
and resistance calibrations to set EEPROM constants. Follow cal-
ibration procedures carefully to ensure that thermocouple and
resistance calibrations do not disturb one another.
Test Equipment Required:
1. Resistance Decades (General Resistance RTD-100, RTD-500/1000, and
RDS-54, or equivalent).
2. Current Source (Fluke 5101B, or equivalent).
3. Digital Multimeter (OMEGA OM7551, or equivalent).
4. Calibration cables per Figure 14.
Ambient Conditions:
Unit should be calibrated at an ambient temperature of 23°C±1°C, with rela-
tive humidity less than 80%.
Preparation For Calibration:
1. Turn off unit, and remove bottom-cover. Refer to Disassembly
Instructions.
2. Secure battery with a piece of adhesive tape.
NOTE: Momentary loss of battery power during the following cal-
ibration will invalidate previous adjustments, both resistance and
thermocouple.
3. Hook up test-equipment and unit per Figure 14.
4. Set current-source to 1mA, STANDBY mode.
5. Set DMM to 2V DC range.
6. Turn on unit.
7. Set unit to METER mode, RTD-100, °F.
8. Turn off unit. Remove jumper J1. Turn on unit. 'RTD' annunciator should
be flashing.
NOTES: Flashing 'RTD' indicates that calibration adjustments
will be written to memory. Avoid selecting thermocouple
functions while in this mode.
NOTES: Should it be necessary to scroll through thermocouple
functions, first hit the OPR key (disables flashing 'RTD'),
and start again at Step 7 above.
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