wtw DIQ/S 282, Operating Manual, Page: 20 / 186

Installation DIQ/S 28X
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DIQ modules are installed must be connected to the local potential equaliza-
tion 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 construc-
tion 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 cable and via the valuable sensor in the
measuring medium.
4 It is recommended to attach a metallic or nonmetallic sun shield to each out-
side location of the DIQ modules. Sun shields protect the electric field lines
in the area of the DIQ module due to an advantageous development of the
electrical field lines in the area of the MIQ module and promote the dissipa-
tion of the surge via the mounting construction.
5 The line voltage for the supply of the IQ S
ENSOR
N
ET
must comply with over-
voltage 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.
6 One part of the safety and lightning protection concept is based on high-
grade protective insulation of the IQ S
ENSOR
N
ET
. It does not have or require
any protective ground conductor or earth terminal. Avoid any direct contact
of any SENSOR connections or the metallic sensor enclosures with the local
grounding or potential equalization system and with metallic construction el-
ements (see point 8).
7 Additional external lightning protection measures, 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.
8 For the realization of the internal lightning protection of the system (e.g.
wastewater treatment plant control stands) and for the protection of external
resources, cable entry points into buildings or distributions coming from the
DIQ/S 28X 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 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