-23-
istence of so-called "mutual resistance‖, R
0
is not the usual parallel
value in the sense of electrical engineering (slightly higher than its
IEC parallel output value). But because a tower-grounding he-
misphere was much smaller than the distance between the towers,
and with a great number of locations after all, R
0
is much smaller
than R
1
. Therefore, it can be justified to assume R
0
=0 from an en-
gineering perspective. In this way, the resistance we measured
should be R1.
Times of comparing tests in different environments and different
occasions with the traditional method proved that the above as-
sumption is entirely reasonable.
2. Limited Point Grounding System
This is also quite common. For example, in some towers, five
towers are linked with each other through overhead ground wire;
Besides, the grounding of some of the buildings is not an inde-
pendent grounding grid, but several grounding bodies connected
with each other through the wire.
Under such circumstances, the above R
0
regarded as 0, will yield
more error on the results of the measurement.
Due to the same reasons mentioned above, we may ignore the
impact of the mutual resistance; and the equivalent resistance of
the grounding resistance paralleled is calculated by the usual
sense. Thus, for the grounding system of N (N is smaller, but larger
than 2) grounding bodies, it can offer N equations:
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