YSI IQ S ENSOR N ET System 182 - Manual (Page 17)

System 182 Installation
3 - 3 ba76022e01 12/2011
7 One part of the IQ S ENSOR N ET safety and lightning protection
concept is based on high-grade protective insulation of the network
components and of the entire 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 realization 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 shield clamps for the contacting of the shield. 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.
– Relay lines should be connected to the local potential
equalization in order to provide general and consistent protection
via gas overvoltage surge arresters.