Practical Application; Multipoint Grounding System - VOLTCRAFT EMZ-1000 Bedienungsanleitung

8. Practical application

a) Multipoint grounding system
Multipoint grounding systems (e.g., grounding systems for power transmission towers, com-
munications cables, certain buildings, etc.) are connected by means of ground wires (shielding
layer of communications cables) to form a grounding system. When the tester is used for meas-
urement, its equivalent circuit diagram is shown in the figure below.
R1 is the target ground resistance.
R0 is the equivalent resistance of the ground resistance of all other earthing rods connected
in parallel
(R0 = R2 // R3 // R4).
The strict grounding theory states that R0 is not the usual parallel value in the sense
of electrical engineering (slightly higher than the IEC parallel output value) due to the
so-called "manual resistance". But since the grounding hemisphere of the individual
towers is much smaller than the distance between the towers, which eventually means
the greater number of earthing points, R0 is much smaller than R1. Therefore, it is
reasonable to assume R0 = 0 from a technical point of view. Thus the measuring
resistor should be R1.
The comparison of tests in different environments and on different occasions with the
traditional method has shown that the above assumption is completely justifiable.
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