Design Calculations of Lightning Protection Systems – Part Eleven

In Article  " Design Calculations of Lightning Protection Systems – Part Two ", I indicated the lightning protection design process involves a number of design steps as in Fig.1.


Fig.1: The Lightning Protection Design Process


Step#1: Characteristics of the Structure to Be Protected
Explained in above Article




Step#2: Risk Assessment Study



Also, In above Article, I indicated that:




Methods Of Calculations For Risk Assessment Study

The risk assessment study can be done by (4) different methods as follows:

1- Manual Method (equations and tables method),which will be explained as per:
  • IEC 62305-2,
  • NFPA780.

2-Software Method,
3- Excel Sheets Method,
4-Online Calculators Method.




First: Manual Method (Equations And Tables Method) as per IEC 62305-2


The Manual Method (Equations and Tables Method) for Calculations of Risk Assessment Study as per IEC 62305-2 can be reviewed in the following Articles:






First: Manual Method (Equations And Tables Method) as per NFPA 780


The Manual Method (Equations and Tables Method) for Calculations of Risk Assessment Study as per IEC 62305-2 can be reviewed in the following Articles:




Second: Software Method For Performing The Risk Assessment Study




As we see in the previous Articles of the First Method: Manual Method (Equations and Tables Method) that the Manual Method is time-consuming and not always easy to apply the procedures and data given.

Hence, most of the lightning designers use various types of software to perform the Risk Assessment Study. I will explain some of these software programs which are:

S/N
Program
By
1
StrikeRisk V5.0
Furse Company
2
RAPAL
Faculty of Engineering- Aristotle University of Thessaloniki
3
Riesgo
Applicationes Tecnologicas Company

Today, I will explain the first software: Strike Risk V5.0 as follows.



I explained the first software: StrikeRisk V5.0 in Article " Design Calculations of Lightning Protection Systems – Part Ten ".

Today, I will explain the Second software: RAPAL for performing the Risk Assessment Study: Software Method.

For more information, please review the following Articles:





RAPAL Software  




First: Why using RAPAL Software?


  • RAPAL is one of the most useful software programs, using risk analysis in accordance with IEC 62305-2:2006, for the evaluation of the necessity for lightning protection of structures and connected services.
  • The software (RAPAL), developed in Visual Basic, runs as a Microsoft Windows application and features a user-friendly graphics interface.
  • The application software is a useful tool for engineers and can also be used for educational purposes in high voltage engineering courses.


When you run the software after installation the start window will appear which gives some information about:


Start Window for RAPAL Software

  1. the authority that produces this software: Faculty of Engineering- Aristotle University of Thessaloniki - Greece,
  2. the followed international standard: IEC 62305-2:2006


Click “IEC 62305-2:2006” button to begin using RAPAL software.





Second: The Construction Of RAPAL Software

This program consists of (7) main windows which are:

  1. Structure's Dimensions,
  2. Structure's Attributes,
  3. Environmental Influences,
  4. Conductive Electric Service Lines,
  5. Protection Measures,
  6. Type Of Loss,
  7. Results.


Notes:

  • Each one of these main windows includes some sub-windows.
  • Each main and sub-main window includes some boxes for data selection/entry.





1- Structure's Dimensions Window

This window divided to (2) sub-windows as follows:

  1. Basic Structure,
  2. Adjacent Structure.


1.1 Basic Structure Sub-window

In this sub-window, select the type of the basic structure from the following types:

Type Of The Basic Structure
Defining Parameters
Rectangular with a flat roof (Fig.1)

Enter width (W), length (L) and height (H) all in meters
Rectangular with a piched gabled roof (Fig.2)

Enter width (W), length (L), height 1 (H1) and height 2 (H2) all in meters
Cylindrical (Fig.3)

Enter diameter (D) and height (H) all in meters
Complex with a known collection area (Fig.4)
Enter Ad/b and  Am all in square meters

Where:
  • Ad/b is the collection area of the isolated structure.
  • Am is the collection area of flashes striking near the structure. (Extends to a line located at a distance of 250 m from the perimeter of the structure).


Fig.1


Fig.2


Fig.3


Fig.4


Also in this sub-window, answer the question: Does an adjacent structure exist?

If you select Yes
You will be go to Adjacent structure sub-window
If you select No
You will be go to Structure's Attributes Window


1.2 Adjacent Structure Sub-window

Note: this sub-window will appear only if you select yes as answer for the question: Does an adjacent structure exist? In above Basic Structure Sub-window.
In this sub-window, select the type of the adjacent structure from the following types:

Type Of The Adjacent Structure
Defining Parameters
Rectangular with a flat roof (Fig.5)
Enter width (W), length (L) and height (H) all in meters
Rectangular with a piched gabled roof (Fig.6)
Enter width (W), length (L), height 1 (H1) and height 2 (H2) all in meters
Cylindrical (Fig.7)
Enter diameter (D) and height (H) all in meters
Complex with a known collection area (Fig.8)
Enter Ad/a in square meters

Where:
  • Ad/a: is the collection area of the adjacent structure.


Fig.5

Fig.6

Fig.7


Fig.8




2- Structure's Attributes Window


Structure's Attributes Window


In this window, we have (3) boxes, each box represent a different parameter as follows:

Parameter
Box Name
Box Selections
Selected Value
Parameter rf in table C.4, IEC 62305-2
Risk of physical damage (include fire)
Explosive
1
High
0.1
Ordinary
0.01
Low
0.001
None
0
Parameter KS1 in page 109, IEC 62305-2
Structure screening effectiveness
Poor
1
Average
0.2
Good
0.01
Parameter KS3 in Table B.5, IEC 62305-2
internal wiring type
Unscreened
1
Screened
0.1
Note: when you make a selection, the value of the parameter appears in the right corner of the box (for example: selection of ordinary, a value of 0.01 appears)





3- Environmental Influences Window


Environmental Influences Window


In this window, we have (4) boxes, some of these boxes represent different parameters as follows:

Parameter
Box Name
Box Selections
Selected Value
Factor Cd/b in Table A.2, IEC 62305-2
Basic structure location factor
Lower than
0.25
Similar in height
0.5
Isolated structure
1
Exposed hilltop
2
Factor Ce in Table A.5, IEC 62305-2

Environmental factor
Urban and tall buildings
0
Urban
0.1
Suburban
0.5
Rural
1
Factor Cd/a in Table A.2, IEC 62305-2
Adjacent structure location factor
Lower than
0.25
Similar in height
0.5
Isolated structure
1
Exposed hilltop
2
Notes:
  • when you make a selection, the value of the parameter appears in the right corner of the box (for example: selection of isolated structure, a value of 1 appears)
  • Box of Adjacent structure location factor will appear only if you select yes as answer for the question: Does an adjacent structure exist? In above Basic Structure Sub-window.


Box#4: Selection of factor Ng

Select factor Ng to be calculated from the following:

Box Selection
Data Entry
Note
Lightning ground flash density (Ng)
Enter value of Ng in flashes/km/year

Thunderstorm days per year (Td)
Enter value of Td in days/year

Ng / Td for Greek counties

Select location and you can view the isokeraunic map of Greece
This selection for Greece only






4- Conductive Electric Service Lines

This window includes (4) sub-windows as follows:

  1. Power line 1,
  2. Power line 2,
  3. Telecommunication line,
  4. Other services.


4.1 Power Line 1 Sub-Window


 Power Line 1 Sub-Window

This sub-window include some boxes which differ according to your selection from:

  • Box#1: Type of Service to the Structure,
  • Box#2: Type of external cable.


This is shown in the below table:

Box#1 selection
Box#2 selection
Box name
Parameter
Box selection
Selected value
Overhead cable
Screened
presence of transformer
factor Ct in Table A.4 in IEC62305-2
No transformer
1
Transformer
0.2
types of apparatus (existing in the building)

-
Uw = 1.5 kV (Electronic)
-
Uw = 2.5 kV (electrical user)
Uw = 4 kV
Uw = 6 kV (electrical network)
the resistance of the cable screen

-
Unknown
-
RS1 (ΩLkm)
move the sliding bar to choose the right value
Protection measure


Parameter Kp1 in Table D.2 in IEC62305-2

No protection measure
1
Additional shielding wires – one conductor
0.6
Additional shielding wires – two conductor
0.4
Lightning protective cable duct
0.1
Lightning protective cable
0.02
Additional shielding wires – steel tube
0.01
Unscreened
presence of transformer
factor Ct in Table A.4 in IEC62305-2
No transformer
1
Transformer
0.2
Screened or Unscreened
Service line parameters
-
Length of service section in meters
move the sliding bar to select the right value
Height of service conductors in meters
move the sliding bar to select the right value

Box#1 selection
Box#2 selection
Box name
Parameter
Box selection
Selected value
Buried cable
Screened
presence of transformer
factor Ct in Table A.4 in IEC62305-2
No transformer
1
Transformer
0.2
types of apparatus (existing in the building)

-
Uw = 1.5 kV (Electronic)
-
Uw = 2.5 kV (electrical user)
Uw = 4 kV
Uw = 6 kV (electrical network)
the resistance of the cable screen

-
Unknown
-
RS1 (ΩLkm)
move the sliding bar to choose the right value
characteristics of the shielded line

parameter Kd1 in Table D.1 in IEC62305-2

With shield in contact with the soil
1
With shield not in contact with the soil
0.4
Protection measure


Parameter Kp1 in Table D.2 in IEC62305-2

No protection measure
1
Additional shielding wires – one conductor
0.6
Additional shielding wires – two conductor
0.4
Lightning protective cable duct
0.1
Lightning protective cable
0.02
Additional shielding wires – steel tube
0.01
Unscreened
presence of transformer
factor Ct in Table A.4 in IEC62305-2
No transformer
1
Transformer
0.2
Screened or Unscreened
Service line parameters
-
Length of service section in meters
move the sliding bar to select the right value
Resistivity of soil in Ω.m
move the sliding bar to select the right value

Note:

If you select “None” from box#1, no additional data is required then click next to go to the next sub-window.

Also in this sub-window, answer the question: Does an additional power line exist?

If you select Yes
You will be go to a sub-window called Power Line 2
If you select No
You will be go to a sub-window: Telecommunication line


4.2 Power Line 2 Sub-window


Power Line 2 Sub-window

The same as in 5.1 Power Line 1 Sub-window, the only difference is in the name of the following parameters:

Box#2 selection
Box name
Parameter for Power Line 1
Parameter for Power Line 2
Screened
Protection measure
Parameter Kp1 in Table D.2 in IEC62305-2
Parameter Kp2 in Table D.2 in IEC62305-2
characteristics of the shielded line
parameter Kd1 in Table D.1 in IEC62305-2

parameter Kd2 in Table D.1 in IEC62305-2



Note:
The sub-window Power Line 2 will not ask you for existing of additional power line (max. number of permitted power lines =2).


4.3 Telecommunication Line Sub-Window


Telecommunication Line Sub-Window

Same as Power Line 1 Sub-Window except there is no question for additional lines.


4.4 Other Services Sub-Window


Other Services Sub-Window

Move the sliding bar to select the appropriate number of other services.






5- Protection Measure Window


Protection Measure Window


This window includes (5) boxes as follows:

Parameter
Box Name
Box Selections
Selected Value
Parameter PA in Table B.1 in IEC 62305-2
Touch up and Step voltage
No protection measure
1
Electrical insulation of exposed down conductor
0.01
Effective soil equipotentialization
0.01
Warning notices
0.1
Parameter PB in Table B.2 in IEC 62305-2
Class of LPS
No LPS
1
Class IV
0.2
Class III
0.1
Class II
0.05
Class I
0.02
Parameter PSPD in Table B.3 in IEC 62305-2
Surge protection (SPD)
No protection
1
Class III – IV
0.03
Class II
0.02
Class I
0.01
Better protection characteristics
0.003
Parameter rp in Table C.3 in IEC 62305-2
Fire protection provisions
No measures
1
Manual system
0.5
Automated system
0.2
Parameters ra and ru in Table C.2 in IEC 62305-2
Type of surface
Agricultural, concrete
0.01
Marble, ceramic
0.001
Gravel, Moquette, carpets
0.0001
Asphalt, linoleum, wood
0.00001





6- Type of Loss Window

This window includes (4) sub-windows as follows:

  1. Type 1- loss of human life sub-window
  2. Type 2- loss of essential public service sub-window
  3. Type 3- loss of cultural heritage sub-window
  4. Type 4- economic loss sub-window


6.1 Type 1- Loss of Human Life Sub-Window


Type 1- Loss of Human Life Sub-Window

This sub-window includes (4) boxes as follows:

Parameter
Box Name
Box Selections
Selected Value
Parameter hz1 in Table C.5 in IEC 62305-2
Special hazards to life
No special hazards
1
Low panic level
2
Average panic level
5
High panic level
10
Evacuation difficulties
5
Environmental hazards
20
Contamination risk
50
Parameter Lt1 in Table C.1 in IEC 62305-2

Type of structure
Persons inside the building
0.0001
Persons outside the building
0.01
Parameter Lf1 in Table C.1 in IEC 62305-2
Life loss due to fire
Hospitals, hotels, civil buildings
0.1
Industrial, commercial, school
0.05
Public entertainment, churches, museums
0.02
Other structure
0.01
Parameter Lo1 in Table C.1 in IEC 62305-2
Life loss due to overvoltage
No relevant
0
Hospitals
0.001
Potentially explosive
0.1


6.2 Type 2- Loss of Essential Public Service Sub-Window


Type 2- Loss of Essential Public Service Sub-Window

This sub-window includes (2) boxes as follows:

Parameter
Box Name
Box Selections
Selected Value
Parameter Lf2 in Table C.6 in IEC 62305-2
Services lost due to fire
No service exist
0
Gas, water supply
0.1
TV, Telecommunication, Power supply
0.01
Parameter Lo2 in Table C.6 in IEC 62305-2
Services lost due to Overvoltages
No service exist
0
Gas, water supply
0.01
TV, Telecommunication, Power supply
0.001


6.3 Type 3- Loss of Cultural Heritage Sub-Window


Type 3- Loss of Cultural Heritage Sub-Window

This sub-window includes one box as follows:

Parameter
Box Name
Box Selections
Selected Value
Parameter Lf3 in page 123 in IEC 62305-2
Culture heritage lost due to fire
No heritage value
0
Irreplaceable value
0.1


6.4 Type 4- Economic Loss Sub-Window


Type 4- Economic Loss Sub-Window

This sub-window includes (5) boxes as follows:

Parameter
Box Name
Box Selections
Selected Value
Parameter hz4 in Table C.5 in IEC 62305-2
Special hazards to economics
No special hazards
1
Environmental hazardous
20
Contamination risk
50
Parameter Lf4 in Table C.7 in IEC 62305-2
Economic loss due to fire
No relevant
0
Hospital, industrial, museum, agricultural
0.5
Hotel, school, office, church, public entertainment, economic building
0.2
Other structures

0.1
Parameter Lo4 in Table C.7 in IEC 62305-2
Economic loss due to overvoltage
No relevant
0
Explosive risk
0.1
Hospital, industrial, office, hotel, economic building
0.01
Museum, agriculture, school, church, public entertainment
0.001
Other structure
0.0001
Parameter Lt4 in Table C.7 in IEC 62305-2
Step/touch potential loss factor
No shock risk
0
Livestock inside
0.0001
Livestock outside
0.01
Parameter Rt4

Tolerable risk of economic loss
1 in 10
1 in 10
1 in 100
1 in 100
1 in 1000
1 in 1000
1 in 10000
1 in 10000
1 in 100000
1 in 100000
5 in 10
5 in 10
5 in 100
5 in 100
5 in 1000
5 in 1000
5 in 10000
5 in 10000
5 in 100000
5 in 100000





7- Results Window

This window includes (3) sub-windows as follows:

  1. Calculated parameters sub-window,
  2. Calculated risks for structure sub-window,
  3. Calculated risks for services sub-window.


7.1 Calculated Parameters Sub-Window


Calculated Parameters Sub-Window

This sub-window includes (2) boxes as follows:

Box name
Contents
Meaning
Collection Areas
Ad/b
The collection area of the isolated structure
Ad/a
The collection area of the adjacent structure
Am
The collection area of flashes striking near the structure. (Extends to a line located at a distance of 250 m from the perimeter of the structure)
AI(pl1)
the collection area of flashes striking the Power line 1
Ai(pl1)
the collection area of flashes to ground near the Power line 1
AI(pl2)
the collection area of flashes striking the Power line 2
Ai(pl2)
the collection area of flashes to ground near the Power line 2
AI(tlc)
the collection area of flashes striking the telecommunication line
Ai(tlc)
the collection area of flashes to ground near the telecommunication line
Average annual number of dangerous events
ND
Number of dangerous events for the structure
NDa
Number of dangerous events for an adjacent structure
NM
the average annual number of dangerous events due to flashes near a structure
NL(pl1)
the average annual number of dangerous events due to flashes to a power line 1
Nl(pl1)
The average annual number of dangerous events due to flashes near a power line 1
NL(pl2)
the average annual number of dangerous events due to flashes to a power line 2
Nl(pl2)
The average annual number of dangerous events due to flashes near a power line 2
NL(tlc)
the average annual number of dangerous events due to flashes to a telecommunication line
Nl(tlc)
The average annual number of dangerous events due to flashes near a telecommunication line


7.2 Calculated Risks for Structure Sub-Window


Calculated Risks for Structure Sub-Window


This sub-window includes (4) boxes as follows:

Loss of human life box
Loss of essential public services box
Loss of cultural heritage box
Economic loss box
RA1
RB2
RB3
RA4
RB1
RC2
RV3
RB4
RC1
RM2

RC4
RM1
RV2

RM4
RU1
RW2

RU4
RV1
RZ2

RV4
RW1


RW4
RZ1


RZ4
Notes:
  • The tolerable risk values are indicated beside each calculated risk value for comparison.
  • if the value of the calculated risks is indicated in red color, so this value exceed the limit of tolerable risk and more protection measures are required by clicking "back to protection measures" button.
  • While the green color means that the value of the calculated risk is within limit of tolerable risk and no more protection measures are required.
  • You can print these results by clicking "print" button.



7.3 Calculated Risks for Services Sub-Window


Calculated Risks for Services Sub-Window

This sub-window includes (3) boxes as follows:

Power Line 1 box
Power Line 2 box
Telecommunication Line box
R’B2(1)
R’B2(2)
R’B2(3)
R’C2(1)
R’C2(2)
R’C2(3)
R’V2(1)
R’V2(2)
R’V2(3)
R’W2(1)
R’W2(2)
R’W2(3)
R’Z2(1)
R’Z2(2)
R’Z2(3)
R’B4(1)
R’B4(2)
R’B4(3)
R’C4(1)
R’C4(2)
R’C4(3)
R’V4(1)
R’V4(2)
R’V4(3)
R’W4(1)
R’W4(2)
R’W4(3)
R’Z4(1)
R’Z4(2)
R’Z4(3)

Calculated risk for each box
Direct strike
+
Indirect strike
=
Total Risk
Tolerable risk
Loss of public services






Economic loss






Notes:
  • if the value of the calculated risks is indicated in red color, so this value exceed the limit of tolerable risk and you need to go back to services lines by clicking "back to services lines " button.
  • While the green color means that the value of the calculated risk is within limit of tolerable risk and no more protection measures are required.
  • You can print these results by clicking "print" button.






Third: End/Exit RAPAL Software?

When all the calculated risk results become within limits of tolerable risk in the two sub-windows calculated risks for structure and calculated risks for services, so you can click exit to end the program season.





To download your copy of RAPAL Software Program, please click on the link.



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In the next Article, I will explain Other Software for performing the Risk Assessment Study. Please, keep following.




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