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radius of the rolling sphere r radius of the rolling sphere r

≤ 8.5 m

≤ 15 m ≤ 12.5 m

Figure 9.3.4 Protection of a fermenter by means of air-termination
masts, isolated by means of a HVI Conductor
(Part No. 819 720)
Figure 9.3.3 Protection of a fermenter with a foil roof by means of
telescopic lightning protection masts
radius of the rolling sphere r
The DEHNiso Combi set according to Table 9.3.1 is used for
the application illustrated in Figure 9.3.2.

Another possibility to avoid direct lightning strikes to ferment-
ers with foil roof is to use steel telescopic lightning protection
masts (Figure 9.3.3). These masts are installed in natural soil ≤ 8.5 m
or in the ground foundation. Free heights above ground level
up to 25 m or in case of customised versions even higher can ≤ 19 m ≤ 16.5 m
be achieved. The standard lengths of the steel telescopic light-
ning protection masts are supplied in partial lengths of 3.5 m,
offering enormous transportation benefits. More detailed in- > 0.2 m
formation on the use of steel telescopic lightning protection
masts can be found in installation instructions No. 1729.
A third possibility to protect fermenters with foil roof from di-
rect lightning strikes is to use a HVI Conductor. HVI Conductors Figure 9.3.5 Protection of a fermenter by means of air-termination
are high-voltage-resistant, insulated conductors with a spe- masts, isolated by means of two HVI Conductors
cial outer sheath. In the field of lightning protection, they are (Part No. 819 750)
typically used as insulated down conductors for keeping the
separation distance according to IEC 62305-3 (EN 62305-3).
To this end, the separation distance must be calculated ac- termination system from the equipotential bonding level
cording to IEC 62305-3 (EN 62305-3). Then it must be checked (earth-termination system) to the air-termination tip is
whether this calculated separation distance can be achieved 15 m (in case of class of LPS II). The maximum free length
by means of the equivalent separation distance of the HVI above the top edge of the fermenter must not exceed
Conductor. There are two possible solutions: 8.5 m (for mechanical reasons).
¨ Solution 1: Air-termination masts with one HVI Conduc- ¨ Solution 2: Air-termination masts with two HVI Conduc-
tor (Figure 9.3.4). The maximum total length of the air- tors (Figure 9.3.5). The maximum total length of the air-

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