wtw DIQ/S 182-XT-4, Operating Manual

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System 182-XT-4 Installation
3 - 7 ba75753e06 12/2014
The internal device-related protective measures are already integrated
in the WTW online measuring technology as so-called 'lightning
protection' (see chapter 9 T
ECHNICAL DATA
).
The external protective measures of the installation environment can
be carried out with respect to the following guidelines:
1 All lines of IQ S
ENSOR
N
ET
systems must be
a) installed inside (or else close to) the grounded metallic mounting
constructions, e.g. handrails, pipes and posts if possible
b) or, particularly in the case of longer lines, laid in the ground.
Background: The formation of highly lightning hazardous inductive
loops between the cables and ground is avoided through the low
clearance of the grounded metal construction or by installation in the
ground.
2 Only the SNCIQ or SNCIQ-UG cable material must be used. This
cable material, particularly the high line cross section of the cable
shielding (1.5 mm²), is an important prerequisite for the hazard-free
discharging of the surge without inadmissibly high overvoltages
developing along the line at the same time that could have a
damaging effect on the individual IQ S
ENSOR
N
ET
components. It is
not recommended to use cables from other manufacturers with
usually appreciably lower shielding conductor cross sections.
3 All metallic mounting constructions, handrails, pipes, posts etc. on
which MIQ modules are installed must be connected to the local
potential equalization system and the grounding system or must be
individually sufficiently grounded locally according to the codes of
practice.
For the individual grounding of the measuring point the mounting
construction must be solidly connected by means of a large-area
auxiliary electrode with the measuring medium.
Metallic control shafts/pipes and other large-area metallic bodies
that reach into the measuring medium are, for example, ideal for use
in the grounding of the mounting construction.
This creates a set path for the main surge. As a result it is possible
to avoid the surge being discharged via the IQ S
ENSOR
N
ET
cable
and via the valuable sensors in the measuring medium.
4 The contacts of the MIQ modules must always be protected by the
associated contact covers if they are not in use. The contact cover
provides improved insulation against the electric fields of a
thunderstorm event through the extension of the air and creepage
paths.
5 It is recommended to attach a metallic or nonmetallic sun shield to
each outside location of the MIQ modules. Sun shields protect the
electric field lines in the area of the MIQ module through an
advantageous development of the electrical field lines in the area of
the MIQ module and promote the dissipation of the surge via the
mounting construction.