Applications; Other Applications - Megger DET5/4R Guia Del Usuario

APPLICATIONS

The installation of satisfactory earthing systems is an
essential part of electricity supply, wiring safety and
installation economics. It is also of great importance in
many communications systems.
The primary application of the DET5/4R and
DET5/4D is in the testing of earth electrodes, whether
these take the form of a single electrode, multiple
electrodes, mesh systems, earth plates or earth strips.
All earthing arrangements
immediately after installation and at periodic intervals
thereafter.
CHOICE OF ELECTRODE SITE
For an earth electrode system to perform satisfactorily
it must always have a low total resistance to earth. This
value will be influenced by the specific resistance of
the surrounding soil.
nature of the soil and its moisture content. Before
sinking an electrode or electrode system it is often
helpful to survey the surrounding area before choosing
the final position for the electrode. It is possible with
these instruments to obtain the resistivity of the soil
over an area and at different levels beneath the surface
of the ground. These resistivity surveys may show
whether any advantage is to be gained by driving
electrodes to a greater depth, rather than increasing
the cost by having to add further electrodes and
associated cables, in order to obtain a specified total
earth system resistance.
should be
This in turn depends on the
EARTHING SYSTEMS MAINTENANCE
After installation, checks may be made on an earthing
system to see if there is any significant change in the
resistance over a period of time or under different soil
moisture conditions, (e.g. brought about by changing
weather conditions or different seasons of the year).
Such checks will indicate if the earth electrode
resistance to earth has been exceeded by changing
tested
soil conditions or ageing of the system.

OTHER APPLICATIONS

For archeological and geological purposes, an
investigation of soil structure and building remains can
be carried out at varying measured depths, by the
resistivity survey technique.
In all cases the accuracy of the instrument readings
may be taken to be higher than the changes caused by
natural variables in soil characteristics.
A further application is in continuity testing, for example
checking the resistance of conductors used in an
earthing circuit.
Resistances between 0,01 Ω and 19,99 kΩ can be
measured with a basic accuracy of ±2% of reading
±3 digits. Individual test spike resistances of up to 4 kΩ
for the Current loop or 75 kΩ for the Potential circuit
can be tolerated on the lowest range, and on the higher
ranges greater Current loop values can exist.
7