YSI IQ SensorNet 2020 XT Terminal - Manual (Page 42)

Installation System 2020 XT USB
3 - 12 ba76019e01 12/2012
7 The IQ S ENSOR N ET safety and lightning protection concept is partly
based on the high-quality protective insulation of the line power
supply units and the total system. It does not have or require any
protective ground (PG) conductor or earth terminal. Avoid any direct
connection of the IQ S
ENSOR N ET connections or the metallic sensor
enclosures with the local grounding or potential equalization system
and with metallic construction elements (see point 9).
8 Additional external lightning protection measures directly on the
IQ S ENSOR N ET system or its components, e.g. the use of
overvoltage surge arresters, are not necessary for protection
against the indirect effects of lightning and could possibly result in
malfunctions.
9 For the realisation of the internal lightning protection of the system
(e.g. wastewater treatment plant control stands) and for the
protection of IQ S
ENSOR N ET external resources, cable entry points
into buildings or distributions coming from the IQ S ENSOR N ET must
be carried out as follows:
– The shield of SNCIQ or SNCIQ-UG cables can be connected to
the local potential equalization with a gas overvoltage surge
arrester. Use shielding terminals for the contacting of the shield
(e.g. those of the PROFIBUS-System). The shield of the cable
must not be opened under any circumstances.
– 0/4-20 mA interfaces must be realized with shielded cables. The
cable shield must be connected directly to the potential
equalization(s) provided. If plant potential equalization systems
are provided on both sides, the shield must also be connected on
both sides. The inner conductors must have no contact with the
potential equalization.
– PROFIBUS cables and Modbus cables have to be installed
according to the prescriptions of the respective bus system.
– Relay lines should be connected to the local potential
equalization in order to provide general and consistent protection
via gas overvoltage surge arresters.