Equipment Operation Checking - TENTECH MTD 20KWe Manual De Uso

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 (62% rule). It should be noted that when measuring GDS
resistances 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, such the "slope
method" developed by Dr. G. Tagg in 1970.
All these considerations refer to physical aspects, essential to the
measurement process, thus they are applied to all earth meters, and do
not depend on the manufacturer or the technology used.

3. Equipment operation checking

Using a standard resistance (i.e. 10.0 Ω nominal), it's possible to test the
equipment calibration. This resistance must be connected to the 4
terminals on the earth meter, as shown in figure 06.
Following this procedure:
The Function Selector Switch  must be in the ρ position (4 pole).
•
The Range Selector Switch must select the 20.00 Ω scale.
•
Start the equipment.
•
Press the Battery Test Button to check the battery charge status.
•
If the display shows a value lower than 1000, the battery should be
recharged or external power supply should be used.
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