Limited Point Grounding System - VOLTCRAFT EMZ-1000 Bedienungsanleitung

b) Limited point grounding system
In some configurations there are five towers connected by overhead lines.
Moreover, in some buildings the grounding system is not an independent grounding grid, but a
combination of multiple grounding bodies that are connected to one another by means of cables.
Under these circumstances, assuming that the above-mentioned R0 value is 0 leads to a larger
error in the measurement results. The effect of mutual resistance is ignored for the same reason
and the equivalent resistance of the ground resistance connected in parallel is calculated in the
usual sense. Thus, N equations can be set up for a grounding system with N grounding bodies
(N is small but larger than 2):
Where: R1, R2 .... RN are the ground resis-
tances of N grounding bodies.
R1T, R2T .... RNT are the resistances meas-
ured with the tester in different grounding paths.
These are non-linear equations with N unknown
numbers and N equations. Although there is a
unique solution, it is very difficult to artificially
solve the problem, even impossible when N is
big.
The user can use a computer programme for
calculating the grounding system with limited
points to obtain the solution.
However, the user must ensure that the number
N
( - 1)
of test values measured for the calculation is
exactly the same as the number of grounding bodies connected to one another in the earth-
ing system, not more or less. In this case, the software will yield the same number of ground
resistance values.
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