Furuno WR2120, Руководство по установке

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A.2.3. Risk assessment conclusion
Values of the risk components for the unprotected structure are reported in the regulation.
The public service loss (L2) and the economic loss (L4) are relevant for this type of structure. It is
required to evaluate the need for protection. This implies the determination of the risk
𝑅
2
for L2 and
risk
𝑅
4
for L4 with the risk components
𝑅
𝐵
, 𝑅
𝐶
, 𝑅
𝑀
, 𝑅
𝑉
, 𝑅
𝑊
and
𝑅
𝑍
and to compare it with the
tolerable risk
𝑅
𝑇
= 10
−3 . Suitable protection measures will be selected to reduce the risk to or
below the tolerable risk.
According to the IEC 62305-2, calculation of the risk parameters is shown as follows:
Damage
Source of damage
S1 S2 S3 S4
D2
𝑅
𝐵
= 𝑁
𝐷
× 𝑃
𝐵
× 𝐿
𝐵
𝑅
𝑉
= (𝑁
𝐿
+ 𝑁
𝐷𝐽
) × 𝑃
𝑉
× 𝐿
𝑉
D3
𝑅
𝐶
= 𝑁
𝐷
× 𝑃
𝐶
× 𝐿
𝐶
𝑅
𝑀
= 𝑁
𝑀
× 𝑃
𝑀
× 𝐿
𝑀
𝑅
𝑊
= (𝑁
𝐿
+ 𝑁
𝐷𝐽
) × 𝑃
𝑊
× 𝐿
𝑊
𝑅
𝑍
= 𝑁
𝐼
× 𝑃
𝑍
× 𝐿
𝑍
Calculation of the risk components requirement is as shown in Table A.5.
Use the Table A.4 and the Table A.5, risk assessment result will be calculated. The result is shown
in the Table A.6. Therefore considering current condition, the weather radar is not protected by
existing lightning rods. Total risk value is exceeded of the tolerable risk value.
We’ll propose solution for this later, protecting the radar by additional lightning rod and adapt LPL
Class IV. Assessment for this solution is also shown in the Table A.6. According to the result is
almost half of the tolerable risk value, so the condition of the radar turned into safe.
Type of damage Symbol Current Condition Protected by LPL IV
D2: Physical Damage
𝑅
𝐵
0 0
𝑅
𝑉
0 0
D3 failure of
internal systems
𝑅
𝐶
0.01 0.0005
𝑅
𝑀
0.1323 1.37 x 10
-6
𝑅
𝑊
3.36 x 10
-6
1.68 x 10
-7
𝑅
𝑍
3.36 x 10
-4
1.68 x 10
-5
Total 0.134 0.00052
Tolerable
𝑅
𝑇
= 0.001
NG Safety
Input parameter Symbol Value
Ground flash density
[1/km
2
/year] 𝑁
𝐺
16.8
Number of over voltages [1/year]
𝑁
𝐷
2.709 x 10
-3
𝑁
𝐷𝐽
0
𝑁
𝑀
13.227
𝑁
𝐿
3.36 x 10
-4
𝑁
𝐼
3.36 x 10
-2
Structure dimensions [m] L, W, H 0.95, 0.95, 3.177
Location factor of structure
𝐶
𝐷
0.5
Table A.4: Risk components for different types of damage and source of damage (IEC 62305-2)
Table A.5: Weather radar at CWRP: Environment and structure characteristics
Table A.6: Risk assessment result at CWRP