2 cable routing, 3 equipotential bonding – Pilz PSSnet GW1 MOD-CAN User Manual
Page 12
Safety
Operating Manual PSSnet GW1 MOD-CAN
1002693-EN-02
12
Cable routing
It is possible to differentiate between cables according to their function. The
following groups exist:
}
Group 1: Data and supply lines for DC voltages below 60 V and AC voltages below 25 V
}
Group 2: Data and supply lines for DC voltages from 60 V to 400 V and AC voltages
from 25 V to 400 V.
}
Group 3: Supply lines above 400 V
Cabling inside buildings:
}
The cable groups listed above should be laid separately.
}
Cables of the same group can be laid within the same cable duct.
}
Cables from group 1 and group 2 should be laid in separate groups or in cable ducts
which are at least 10 cm apart.
}
Cables from group 1 and group 3 should be laid in separate groups or in cable ducts
which are at least 50 cm apart.
}
Data and signal lines should be laid as close as possible to an earthed surface.
Cabling to open air systems:
}
As far as possible use metal conduits. These should be electrically connected and
earthed.
}
Ensure there is sufficient protection against lightning by using metal conduits earthed at
both ends, or concrete cable ducts with reinforcements connected across the joints.
Equipotential bonding
Potential differences can occur if the devices are connected to different earth or ground
connections. Even cable shields that are connected at either end and have different earth
connections can cause potential differences. In order to avoid interference, equipotential
bonding cables must be installed.
In doing so you must ensure the following:
}
Select a low impedance equipotential bonding cable.
}
Select the following as standard values for the cross section of the equipotential bond-
ing cables:
– 16 mm
2
for equipotential bonding cable up to 200 m in length
– 25 mm
2
for equipotential bonding cable over 200 m in length
}
If the control system devices are connected with shielded signal cables which are
earthed at either end, the impedance is calculated as follows:
– Impedance equipotential bonding cable = 10 % of shield impedance
}
Use copper or galvanised steel equipotential bonding cable.
}
Connect equipotential bonding cables to the earth bar over as wide a surface area as
possible.
}
As short a distance as possible should be kept between the equipotential bonding cable
and signal cable.
3.1.1.2
3.1.1.3