Testboy TV 455 - Page 51

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TV 450/455 Line impedance
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Figure 5.34: Resistance to earth, measurement of a lighting protection system
Earth resistance measurements, common measurement procedure
 Select EARTH function using the function selector switch.
 Enable and set limit value (optional).
 Connect test leads to the instrument
 Connect the item to be tested (see figures 5.33, 5.34).
 Press the TEST key to perform the measurement..
 Store the result by pressing the MEM key.
Figure 5.35: Example of earth resistance measurement result
Displayed results for earth resistance measurement:
R..............Earth resistance,
Rp............Resistance of S (potential) probe,
Rc............Resistance of H (current) probe.
Notes:
 High resistance of S and H probes could influence the measurement results. In
this case, “Rp” and “Rc” warnings are displayed. There is no pass / fail indication
in this case.
 High noise currents and voltages in earth could influence the measurement
results. The tester displays the “noise” warning in this case.
 Probes must be placed at sufficient distance from the measured object.