FI002K0018v1530hUK – THS/21 Instruction manual for installation, use and maintenance
3
INSTALLATION
ORIGINAL
INSTRUCTION
63
3.1.3.4 Ground loops prevention
Ground loops are unwanted or uncontrolled currents along the earth connection, which generate
noises and interfere with the functioning of the Metal Detector.
- Keep the Metal Detector Detection Probe insulated from the load-bearing structure and from
other metal structures or conductors. For Metal Detectors not integrated in CEIA systems,
refer to the section on Mechanical Installation in the Metal Detector Installation Manual.
- Keep the load-bearing structure of the Metal Detector insulated from other metal structures or
conductors.
- Avoid any mechanical or ground connection to by-pass the electric insulation of the Probe
supports. For Metal Detectors not integrated in CEIA systems, refer to the section on
Mechanical Installation in the Metal Detector Installation Manual.
- Use a dedicated earth connection for the Metal
Detector, which comes directly from the electricity
supply board.
QE
: electricity supply board;
M1
: machine 1
M2
: machine 2;
MD
: Metal Detector.
QE
M1
M2
MD
POWER BOX
- Connect the motors driven by the inverter (of the Metal Detector transport system and near it)
using screened tearth cable: the frame of the motor and the screen must be
connected only to the PE terminal of the inverter.
- Provide the connection cable to the motor with a ferrite to be placed near the inverter, passing
one or more coils of the phase conductors through the ferrite itself.
- Prevent electric motors driven by the inverter (placed near the Metal Detector) from having the
frame connected electrically to the load-bearing metal structure.
- Keep all metal frames, of the devices connected to the Metal Detector (i.e. encoder), insulated
from the loaf-bearing structure and connect them to the ground only towards the power supply
box.
- The connections of external signals, to the Metal Detector, shall use clean contacts (relais) or
signals insulated from the ground of the device which generates them (i.e. using optocouplers).
Check that the signal cable shield is connected to the ground only towards the power supply
box.
- Check the absence of possible ground loops generated by the interconnection of equipotential
circuits of devices beside the System.
IMPORTANT
: Do not connect the Metal Detector Probe to earth because this is already earthed over the connecting
cable to the power supply.
