Furuno WR110, Руководство по установке

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53
The collection
𝐴
𝑀
extends to a line located at a distance of 500 m from the perimeter of the
structure:
𝐴
𝑀
= 2 × 500 × (𝐿 + 𝑊) + 𝜋 × 500
2
where length L and width W of the structure are expressed in meter. Therefore the
𝐴
𝑀
and
𝑁
𝑀
will be leaded as follows:
𝐴
𝑀
= 2 × 500 × (0.95 + 0.95) + 𝜋 × 500
2
= 787298.16
𝑁
𝑀
= 16.8 × 787298.16 × 10
−6
= 13.227
III. Assessment of the average annual number of dangerous events
𝑵
𝑳
due to flashes to a
line.
𝑁
𝐿
= 𝑁
𝐺
× 𝐴
𝐿
× 𝐶
𝐼
× 𝐶
𝐸
× 𝐶
𝑇
× 10
−6
Therefor
𝐶
𝐼
= 1, 𝐶
𝑇
= 1, 𝐶
𝐸
= 0.01, 𝐴
𝐿
= 2000
for CWRP condition,
𝑁
𝐿
= 3.36 × 10
−4
IV. Assessment of the average annual number of dangerous events
𝑵
𝑰
due to flashes near
a line.
𝑁
𝐼
= 𝑁
𝐺
× 𝐴
𝐼
× 𝐶
𝐼
× 𝐶
𝐸
× 𝐶
𝑇
× 10
−6
Therefor
𝐶
𝐼
= 1, 𝐶
𝑇
= 1, 𝐶
𝐸
= 0.01, 𝐴
𝐼
= 200000
for CWRP condition,
𝑁
𝐿
= 3.36 × 10
−2
Assessment of probability
𝑷
𝑿
of damage:
The probabilities are given in the Annex B of IEC 62305-2. Based on practical condition, the
values are shown in the
Table A. 2
.
Assessment of amount of loss
𝑳
𝑿
:
The values of amount of loss
𝐿
𝑋
should be evaluated and fixed by the lightning protection
designer (or the owner of the structure). The typical mean values of loss
𝐿
𝑋
in a structure
given in the Annex C of IEC 62305-2 are merely values proposed by the IEC.
The loss
𝐿
𝑋
refers to the mean relative amount of a particular type of damage for one
dangerous event caused by a lightning flash, considering both its extent and effects. The loss
value
𝐿
𝑋
varies the type of loss considered the weather radar will be classified to L2 and L4.
Type of damage
Loss D2 D3
L2
𝐿
𝐵
= 𝐿
𝑉
= 𝑟
𝑝
× 𝑟
𝑓
× 𝐿
𝐹
× 𝑛
𝑧
𝑛
𝑡
⁄ 𝐿
𝐶
= 𝐿
𝑀
= 𝐿
𝑊
= 𝐿
𝑍
= 𝐿
𝑂
× 𝑛
𝑧
𝑛
𝑡
⁄
L4
𝐿
𝐵
= 𝐿
𝑉
= 𝑟
𝑝
× 𝑟
𝑓
× 𝐿
𝐹
× (𝑐
𝑎
+ 𝑐
𝑏
+ 𝑐
𝑐
+ 𝑐
𝑠
) × 𝑐
𝑡
𝐿
𝐶
= 𝐿
𝑀
= 𝐿
𝑊
= 𝐿
𝑍
= 𝐿
𝑂
× 𝑐
𝑠
𝑐
𝑡
⁄
where
𝐿
𝑂
is the typical mean relative value of all goods damaged by failure of internal systems (D3)
due to one dangerous event. It will be
10
−2 for structures of hospital, industrial, office, hotel
and commercial.
𝐿
𝐹
is the typical mean relative value of all goods damaged by physical damage (D2) due to
one dangerous event. It will be 0.5 for structures of hospital, industrial, museum and
agricultural.
𝑟
𝑓
is the factor reducing the loss due to physical damage depending on the risk of fire. It will
be 0 for the weather radar.
Finally, we can get the values as follows:
𝐿
𝐵
= 𝐿
𝑉
= 0
𝐿
𝐶
= 𝐿
𝑀
= 𝐿
𝑊
= 𝐿
𝑍
= 10
−2
Characteristics of structure LPL
𝑷
𝑩
𝑷
𝑪
𝑷
𝑴
𝑷
𝑽
𝑷
𝑾
𝑷
𝒁
No protection device — 1 1 1 1 1 1
Protected by
required components
IV 0.2 0.05 1.04 x 10
-5
0.05 0.05 0.05
III 0.1 0.05 1.04 x 10
-5
0.05 0.05 0.05
II 0.05 0.02 4.15 x 10
-6
0.02 0.02 0.02
I 0.02 0.01 2.07 x 10
-6
0.01 0.01 0.01
Table A. 2: Values of probability
𝑷
𝑿
depending on the protection measures to reduce physical damage
Table A. 3: Type of loss L2 and L4: Loss values for each type of damage