8/12/2019 Lightning Risk Study

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8/12/2019 Lightning Risk Study

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Risk Assessment

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Part 3: Physical Damage and Life Hazard

Part 4: Electrical and Electronic Systems within Structures

Part 5: Services (telecoms, power lines, etc.)

The IEC 62305-2 standard gives an extensive risk assessment for the structure, its contents

and connected services. The important input information includes:

- Lightning Ground Flash Density

- Structure Data

- Electrical Lines Data

- Definition and Characteristics of Zones

The selection of most suitable protection measures is made according to the share of risk

components and according to the technical and economical aspects of the different protection

measures. Typically, this type of risk analysis requires a detailed dialog between Alltec

Engineers and the client, resulting in a highly customized and useful analysis. Contact Alltec for

details and to plan an IEC 62305 Risk Assessment for your facility.

Risk Assessment using Lightning Shielding Analysis Software

Computer software modeling and 3-dimensional analysis of lightning risks offers a valuable tool

to evaluate the vulnerability of any structure or facility to direct strike lightning, and provides a

particular insight into what to expect at any specific structure located anywhere in the world.

During the analysis, calculated lightning trajectories for each current crest value are considered

and displayed graphically. Additionally, the results can be viewed in tabular form showing theexposed area (m2) and expected number of strikes corresponding to the crest value of return

stroke current (kA), indicating which areas are vulnerable to what magnitude of lightning current.

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8/12/2019 Lightning Risk Study

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Risk Assessment

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Click on the Image for a Larger ViewThe location of the facility under consideration is where the isokeraunic level may be consideredas high as 100. Lightning model parameters chosen to determine the observed risk analysis forthe 3-dimensional model above facility are shown in the screen shot below.

Click on the Image for a Larger ViewUsing Electro-geometric modeling applied to the 3-dimensional representation of the facility, allof the lightning attachment points are calculated and displayed visually. The software searchesa sky grid for possible sources of lightning strikes. The possible sources and termination pointsare evaluated for probability and a graphical representation of these locations is created. (NewPictures)

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8/12/2019 Lightning Risk Study

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Risk Assessment

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Click on the Image for a Larger ViewA lightning shielding analysis chart is created to show the structural surface area exposed toeach level of lightning current. A series of twenty lightning current values from 5kA to 200kA areevaluated for possible points of termination on the structure included in the 3-dimensionalmodel. The total individual possibilities can be added together to obtain the total number ofexpected strikes per year. In the case shown, the total number of expected strikes from theanalysis is calculated to be 0.503, which means that there is a probability of a direct lightningstrike to the structure once every two years.Alltec Engineers will work with you to create an accurate 3-dimensional model of your facility,and employ that model to highlight strengths, weaknesses and vulnerability to lightning. Large,multifaceted facilities may be modeled to determine relative priorities in risk/benefit studies andconstruction sequence planning. Contact an Alltec Engineer to ascertain if a lightning shieldinganalysis using electro-geometric modeling is right for you.

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