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operations building
measuring point
MCE

Protection for… Type Part No.
DEHNguard DG M TN 275 952 200
TN system
Power supply DEHNguard DG M TN 275 FM 952 205
system DEHNguard DG M TT 2P 275 or 952 110
TT system
DEHNguard DG M TT 2P 275 FM 952 115
Oxygen measure- e.g. 4 to 20 mA BLITZDUCTOR BXT ML4 BE S 24 + BXT BAS base part or 920 224 + 920 300
ment device BLITZDUCTOR BXT ML2 BE 24 + BXT BAS base part 920 324 + 920 300
Figure 9.4.2 Division of the operations building into lightning protection zones; example: selection of surge protective devices for the oxygen
measurement device

ing to the previous IEC 62305-1 (EN 62305-1) standard, plies with the recommendations in the German VdS pub-
VGA 280/4 surge protective devices (SPDs) installed at the lication 2010).
entrance point of the 230/400 V power supply line into the ¨ Installation of type 1 SPDs according to IEC 61643-11
building, VM 280 SPDs of requirement class C installed (EN 61643-11) (power supply) and SPDs of category D1
in the switchgear cabinets of the measuring and control according to IEC 61643-21 (EN 61643-21) for the informa-
equipment). tion technology lines (measuring and control lines as well
as telecommunication lines) at the zone transitions from
¨ The following types of loss are relevant: L2: Loss of service LPZ 0 A to 1.
to the public (water supply and wastewater disposal) and ¨ Type 2 SPDs according to IEC 61643-11 (EN 61643-11)
L4: Loss of economic value (structures and their contents). (power supply) and surge protective devices of category C2
Type of damage L1: Loss of human life was excluded since according to IEC 61643-21 (EN 61643-21) for the informa-
the plant will be fully automated at a later date. tion technology lines (measuring and control lines as well
An assessment of the actual state shows that the calculated as telecommunication lines) at the zone transitions from
risk R for the types of damage L2 and L4 is still considerably LPZ 0 B to 1 and 1 to 2.
higher than the tolerable risk R T .
Lightning protection zone concept
To ensure maximum technical and economic protection, the
Possible protection measures are taken to ensure R < R T for operations building is subdivided into lightning protection
both types of damage:
zones (LPZs). Subsequently, a risk analysis is carried out for
¨ Installation of a lightning protection system with class of each LPZ and the relevant types of damage. The mutual de-
LPS III according to IEC 62305-3 (EN 62305-3) (this com- pendences of the LPZs are then examined and the required

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