Generally, GDS dimensions are greater than those of the auxiliary current
rod, thus its area of influence diameter is also greater. So, in order to
comply with the required condition, the probe must be set up closer to the
current rod than to the GDS. A distance of 62% is usually adopted as a
first try. It should be noted that when measuring GDS resistance in large
systems (such as a large grid that underlies a substation) distances of
hundreds of meters are required to fulfil the condition. Technical literature
describes alternative methods that make it possible to reduce those
distances with valid results.
Note:
all these observations refer to physical aspects essential to the
measurement process, being applied to all earth meters, regardless of
manufacturer or technology.
7. Spurious voltages measurement
In order to check the existence and measure eventual parasitic currents in
the soil, the rods must be set up in the same position used to perform
grounding diffusion measurements.
After placing the rods, press the
key. The display will show the
voltage between the system and the voltage rod, up to a maximum of
60 V.
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