Pilz PSSnet GW1 MOD­-CAN Operating Manual page 12

Safety
}
DC coupling:
DC coupling occurs if the source and sink of interference have common cable connec­
tions. The common cable presents complex resistances, inducing potential differences.
Typical sources of interference are switches/relays, running motors or varying poten­
tials for other systems on the same power supply.
} Capacitive (electrical) coupling:
A different potential between the source and interference sink (e.g. two cables) creates
an electrical field. Coupling is proportional to the rate of voltage change.
Typical sources of interference are contactors, static discharge, parallel signal cables.
} Inductive (magnetic) coupling:
A live cable produces a magnetic field which also surrounds adjacent cables. Interfer­
ence voltage is induced. Coupling is proportional to the rate of current change.
Typical sources of interference are mains cables running in parallel, live cables, high
frequency cables, inductors, transformers, motors.
}
Electromagnetic coupling:
A cable can emit a signal as a radio wave. This wave is then picked up by another
cable.
Typical sources of interference are transmitters such as radios, sparks from spark
plugs, welding equipment, etc.
}
Static discharge:
Static discharge occurs where there are very high differences in potential between two
points. If the two points are brought closer together or if the potential difference is in­
creased, discharges can occur in the air gaps.
Typical sources of interference are people who are statically charged from a synthetic
carpet, for example.
3.1.1.1 Connecting the earth cables
Please note:
} A conductor cross section of at least 2.5 mm
central earth bar. Connections should be kept as short as possible.
} Connections to the earth bar should always be in star form.
}
Connect together the 0V connections on all the 24 V power supplies and earth the 0 V
mains at a single point, or ensure that measures are in place to monitor for earth faults.
Earthed supply voltages offer the best noise immunity.
} The connection of the 0 V supply to the central earth bar or earth fault monitor must be
in accordance with relevant national regulations (such as EN 60204­1, NFPA 79:17­7,
NEC: Article 250).
}
Connections should be protected from corrosion.
Operating Manual PSSnet GW1 MOD­CAN
1002693­EN­03
NOTICE
Powerful HF transmitters should only be operated at a distance of more
than 0.6 m.
2
should be used for the connection to the
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