wtw DIQ/S 182-MOD System Operating Manual page 17

System 182
ba75504e07 04/2012
with overvoltage category II. Generally this is ensured through the
public operator of the power supply networks. In company-owned
networks, e.g. in all power supply systems owned by wastewater
treatment plants, this must be kept separate by a potential
equalization and a surge protection system for the plant.
7 One part of the IQ S
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
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 N system or its components, e.g. the use of
ENSOR ET
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
into buildings or distributions coming from the IQ S
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. Shielding terminals (e. g. of the Modbus system) have
to be used to contact 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.
– The Modbus cables have to be installed according to the rules of
the relevant 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.
N safety and lightning protection
ENSOR ET
N
ENSOR ET
N external resources, cable entry points
ENSOR ET
Installation
connections or the metallic
N
ENSOR ET
must
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