Fluke 1625 FE 1625 Users Manual - Page 40

1625 Users Manual 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 Probe Auxiliary earth electrode >20 m >20 m edw010.eps Figure 7. Measurement of Interference - Voltages and Frequencies Measurement of Earthing Resistances This instrument is equipped with a 3 pole as well as a 4 pole resistance measurement which renders measurements of resistances of earthing systems possible, as well as measurements of the soil resistivity of geological strata. A specific description of the different applications is given further on in this manual. As a special function, the instrument offers measurements with an external current transformer, with which a measurement of single resistance branches in interlinked networks (lightning protection and high voltage pylons with cabling) can be performed without seperating parts of the system. To ensure most feasible interference suppression during measurements, the instrument is equipped with 4 measuring frequencies (94 Hz, 105 Hz, 111 Hz, 128 Hz), with automatic switch over if necessary (AFC - Automatic Frequency Control). The corresponding measuring frequency used for a specific measurement can be called and displayed with "DISPLAY MENU" after the measurement. Additionally, one of the four measuring frequencies can be selected and permanently set in special cases. In that case, in order to stabilize the display, an average measurement can be carried out for up to 1 minute by keeping the "START TEST" button pressed. To determine the earthing impedance (R*) a measurement with a frequency close to the mains frequency (55 Hz) is carried out. At the activation of R* through user's code, this measuring frequency is activated automatically. 32