Title: Why does my 1529 read differently than my DMM?
Applies To: 1529
Problem Description: Found the different results using 1529 (Fluke) and 3456A HP (HP)
A DMM, especially an older model, is not a good choice to measure temperature using a PRT, especially a low resistance PRT such as the 5624. There can be significant measurement errors caused by the meter's accuracy at low resistance, PRT self-heating from the source current, and thermoelectric EMF. The 1529 manages the measurement errors better by using smaller source current and reversing the current to eliminate the thermoelectric EMF effect. Different equipment might also have different sensitivity to induced electrical interference which can be produced by the large AC current and voltage in the furnace heaters. It would be best to compare the results of the 1529 against a 1594A/1595A which will have much lower measurement uncertainty than either the 1529 or DMM.