Fluke 1551A-12 Calibration Guide - Page 16

1551A Ex/1552A Ex Calibration Manual At each calibration point the measurement error may be calculated by subtracting the reference thermometer temperature from the 1551A Ex/1552A Ex temperature. The temperatures and measurement errors may be recorded in Table 5. Table 5. As-found Measurement Errors Point 1 2 3 4 5 Reference (fill in) 1551A Ex/1552A Ex (fill in) Error (fill in) If the measurement errors are well within the specified accuracy, it may not be necessary to adjust the calibration parameters. If the error is larger than desired (say 50 % of the specified accuracy), then adjustments to the Product calibration parameters are necessary. Proceed to the next section. Adjustment at the Low Calibration Point When necessary, the first adjustment is made for the low end of the temperature range of the Product. Set the bath temperature to the Low Adjustment Temperature given in Table 6, depending on the model. Make sure the temperatures of the bath, reference thermometer, and Product are settled and stable before proceeding. Table 6. Low-Adjustment Temperature Point Low −50 °C 1551A Ex −80 °C 1552A Ex Before adjustments to any calibration parameters can be made, access to the protected calibration parameters must be enabled by sending the following command to the Product through the serial interface: SYST:PASS:CEN The parameter is the current password, originally "1234". To make an automatic adjustment at the low calibration point, issue the following command: CAL:USER:LOW The parameter is the temperature of the bath as measured by the reference thermometer. Product accepts a temperature value with up to three decimal places of resolution. The temperature value must be in the same unit in which the 1551A Ex/1552A Ex is measuring. The command will set the value of the CAL:USER:TEMP1 parameter to the given temperature and automatically adjust the CAL:USER:ADJ1 parameter to cause the Product to measure the given temperature accurately. The adjustment made here will not affect the measurements at the other Adjustment temperatures. Allow the readings of the Product to settle and then verify that the readings match the temperature of the reference thermometer and are well within the specified accuracy of the 1551A Ex/1552A Ex. 8