GReTA
–
Installation manual
LSI LASTEM SRL
INSTUM_04546_en
Pag. 5 / 10
If the system is powered by power grid, there is a presence of potentially dangerous voltage inside the box;
the mains voltage is connected to the circuit breaker; this can be deactivated to remove the presence of
mains voltage in places other than the switch itself; however, consider that the high voltage is generated
during the measurements even if only the battery voltage is available. If you want to shut down the system
completely use the switch located on the top of the
PWR
unit.
The electrical cables that bring the connections back to the measuring electrodes also carry currents with
potentially dangerous voltages. LSI LASTEM has carefully considered the safety conditions for those working
with
GReTA-ONE
, in particular the situation in which a subject could come into contact with the measuring
electrodes. In this regard, the following should be considered:
•
Each individual electrode is powered by the system only for short instants and quite rarely (alto-
gether a few seconds in each measurement session; typically, there is only one scheduled measure-
ment session each day).
The electrocution can occur by holding in the hands two electrodes that at a given moment are activated by
the system to perform the measurement in the ground right at the position of the subject. It should be con-
sidered that the typical duration of the injection is about 300 ms x 2 (twice because for each measurement
the injection is considered in the opposite direction and then in the direct direction for the depolarization of
the soil) and 1000 ms x 2 at the most, therefore still insufficient to cause death. Considering a condition highly
unlikely to occur, but not theoretically impossible, in which the operator is in contact with two electrodes,
the instrument is performing a measurement precisely on those elements and, fatally, just at that moment a
block to the automatic signal switching system occurs, in this case there would be a permanent presence of
the voltage to the electrodes in contact with the subject; in this situation there is a circuit specifically provided
in the instrument that can detect the system’s block condition and therefore authoritative in the deactivation
command of the entire high voltage supply system. This circuit, in order to ensure maximum operating con-
ditions and reliability, works with dedicated hardware and is completely independent from the other parts
of the injection and measurement system managed by the logical units of the instrument.
1.3
Pre-installation requirements
1.3.1
Power connection
Whenever available at the installation site, the G.Re.T.A. system should preferably be connected directly to
the electrical grid. For this purpose, a 230 Vac power line should be laid in order to reach the plinth and have
sufficient spare cable to reach the G.Re.T.
A. box located approximately at 1 m height from the soil’s surface.
If the electric grid is not available at the installation site, the system may be powered by a solar panel placed
on top of the pole.
1.3.2
Internet connection
The G.Re.T.A. system communicates via Internet connection. The system comes with a 3G/4G modem/router
however without a SIM card, which must be provided locally by the user. Make sure to make available a
3G/4G SIM card at the day of installation and to have tested the coverage of the related telephone operator
at the installation site beforehand.