Fluke 1625 FE 1625 Users Manual - Page 52
Compensation of Earth Electrode Connecting Lead, Measuring process
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1625 Users Manual Example: Your clip-on transformer has a transformation ratio of tr = 1000:1. The measurement without clip-on transformer results in a value RE = 0.983 Ω . With a clip-on transformer a value of RE = 1.175 Ω is measured. The deviation thus reads (1.175 - 0.983) Ω= + 0.192 Ω and referring to RE = 0.983 Ω an error evolves as following: 100% × 0.192Ω = +19.5% 0.983Ω The new transformation ratio to be set calculates: trnew = 1000 × 1.175 = 1195 0.983 Compensation of Earth Electrode Connecting Lead If the line resistance to the earth electrode can not be ignored, a compensation of the connecting lead resistance to the earth electrode is possible. Proceed as described below: Measuring process: START TEST 1625 EARTH / GROUND TESTER H /C2 DISPLAY MENU Earth/Ground Resistance 300 k RA CHANGE ITEM 4 POLE 3 POLE 4 POLE 3 POLE AC Resistance 300 k R DC Low Resistance 3k R 2 POLE 2 POLE 4 POLE SELECT OFF S/P2 ES/P1 E /C1 Earth electrode Auxiliary earth electrode edw019.eps Figure 15. Compensation of Earth Electrode Connecting Lead 1. Turn central rotary switch to position "RE 3pole". 2. Wire instrument according to picture. 44