Installing the 3TB in a borehole
For boreholes with a metallic casing at the bottom and
plastic above, we recommend connecting a cable
between the sensor housing and the ground plate so
that the lower borehole casing acts as the earthing
point.
If there is a significant distance (>30 metres) between
the borehole and the surface installation, the
resistance of the earth cable may make it impractical
to use the borehole as an earthing point. In these
cases, you will have to connect the local ground plate
to an earth stake near to the enclosure; any coupling
between this sensor-local earth line and ground lines
for other parts of the system must be minimized.
4.4.2 Installations with DC power supplies
Güralp sensors require a 12 to 36 V DC power supply. In
most cases, this is provided by an isolating DC/DC
converter installed at the surface. This converter can
be earthed to the local ground plate as above.
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Issue G - November 2019
