Logic DLC NET Series Use And Maintenance Manual page 17

USE AND MAINTENANCE MANUAL – DLC
3.3 Board connections
3.3.1 Power supply
3.3.2 Load cell
3.3.3 Ground connections
LOGIC S.r.l. - M0145Db.docx
Mod. L0006A01 of 30/05/2016
NET
Series
This instrument is an electrical apparatus: it must therefore be installed by
trained personnel. Start-up, maintenance and the following tests must be
carried out by qualified personnel.
Use a power supply cable, with suitable protection to the environment in which
they are installed, with a maximum diameter of 1,5 mm
The load cell provides a low-level signal (a few millivolts); it is therefore essential
for a correct application, use good quality shielded cables. For single-cell
applications with distance equal to or less than 8 meters is enough the 4-wire
connection.
The connection to the load cells must be done with high quality shielded
cable. The cable CAB-TS6 Logic model is recommended for all industrial
applications including areas with risk of explosion.
In applications with more load cells (platforms, tanks, silos, etc.), It is
recommended the use of junction boxes that minimize differences in impedance or
compensation on the signal branches. The junction boxes JBOX series have been
designed for this purpose and properly solve the problem.
The maximum cable length between the junction box and the instrument, depends
on the specific situation of electrical noise in the plant, which potentially can induce
noise on the signal cable. In normal situations cable lengths up to 300 meters can
be used without problems.
The shielded cable must be positioned preferably in metal conduit grounded and in
any case away from any other power supply cable or power cable.
Verify, before and during the installation of the cable cells, which do not occur
entry of moisture in the same cable, causing loss of insulation and consequent
malfunction.
The ground connection is very important for compliance with electromagnetic
compatibility and therefore for the reliability of the apparatus.
Respect and carefully check ground connections indicated on the attached
diagrams in order to prevent possible malfunctions. Connect the shielded cable to
the GND terminal of the terminal blocks; the other end of the screen normally is
isolated.
In presence of strong interferences (inverter etc.), connect to ground both
heads of the screen. In this case it is important to have low values of ground
resistance.
Installation
2
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