FURSE GUIDE TO BS EN 62305 PDF

Furse have now launched an updated Guide to BS EN Protection Against Lightning. This latest edition incorporates guidance on the. This handbook offers a guide for any designers of the structural Lightning protection system to comply with the requirements of BS EN range of standards. An overview of BS EN , its impact on lightning protection and the support and advice Earthing design considerations and full details of the Furse range of earthing materials .. illustrations and design examples, the Guide provides.

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A Guide to BS EN Protection Against Lightning_图文_百度文库

Swell Electrical noise or radio frequency interference RFI is a continuous high frequency 5kHz or more distortion of the normal sine wave. This significant increase in magnitude of the design current capability raises, we believe, one or two debatable issues. The general principle is that the equipment requiring protection should be located in an LPZ whose electromagnetic characteristics are compatible with the equipment stress withstand or immunity capability.

The method of determining the separation distance is dealt with on page 65, Separation isolation distance of the external LPS. Possible protection measures include adequate insulation of exposed conductive parts that could come in contact with the person. This should be bonded to both the meshed earthing system and also to the common cable entry point, at both ends. The designer initially identifies the types of loss that could result from damage due to lightning. So on all structures particularly with flat roofs, the perimeter conductors should be installed as close to the outer edges of the roof as is practicable.

This arrangement is suitable for small sensitive structures such as explosive stores. Lateral connections either by fortuitous metalwork or external conductors made to the down conductors at regular intervals see Table 4. BS EN part 5which relates to this latter type of damage, will ultimately be deleted from the standard.

Lightning Protection Standard BS EN 62305

This is over 8 times the level tolerated by many electronic systems. The collection area is based on a ratio of 1: The main body of this part of the standard gives guidance on the classification of a Lightning Protection Systems LPSexternal and internal LPS and maintenance and inspection programmes.

The armouring of metallic electrical services such as power and telecommunication lines can be directly bonded to the main earthing bar at the service entrance.

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The SPDs ability to survive and achieve a suitable protection level when installed clearly depends upon the size of the overvoltage it will be subject to. Ideal Faraday Cage This, in essence, would prevent the penetration of the lightning current and the associated electromagnetic field into the structure.

Taking this factor into account, the worst case surge that could be expected 62035 a two-wire telephone or data line fugse 2. BS EN advocates the following, in any combination, for the design of the air termination. Protection against lightning is required if the risk R whether this be R1, R2 or R3 is greater than the tolerable risk RT. Continuous metal box – ideal Faraday Cage Welded or clamped joint at every reinforcing bar crossing or reinforcing bar to metal frame connection Table 5.

The outcome was to remain with the information housed within this standard. If however, the risk Rn is greater than RT then protection is required and further calculations are needed to determine exactly what protection measures are required to bring the value below that of RT.

Material and dimensions of electromagnetic shields Table 3 of BS EN details the requirements for the materials and dimensions of electromagnetic shields such as metallic cable trays and equipment enclosures. This is particularly important for the shield of LPZ 1, due to the partial lightning currents flowing through it. This is particularly the case for SPDs installed in parallel shunt on power installations.

This method is suitable where plain surfaces require protection if the following conditions are met: For example, points on a structure equidistant from the last step of the downward leader are equally guode to receive a lightning strike, whereas points further away are less likely tuide be struck see Figure 4. These values are more realistic in practice taking account of factors such as the line impedance and conductor cross-sectional area as discussed previously.

R3 — Risk of loss of cultural heritage covers all historic buildings and monuments, where the focus is on the loss of the structure itself.

Therefore a simple air rod is gkide a cone of protection by sweeping the line AC at the angle of protection a full ? Down conductors should not be installed in gutters or down spouts even if they are insulated due to the risk of corrosion occurring.

Additionally cable systems should avoid being installed close to the shields of any LPZ within the structure.

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Furse release 3rd edition of their renowned Guide to Lightning Protection

R1 — Risk of loss of human life is by far the most important risk to consider, and as such the examples and subsequent discussions relating to BS EN Risk management will focus largely on R1. However the live conductors within these service cables need to be equipotentially bonded at the service entrance through the use of SPDs.

Poor coordination could mean that an overvoltage SPD is subjected to an excess of surge energy placing both itself and connected equipment at risk from damage. One of the major protection measures required is to ensure adequate protection is afforded to the upper sides of these super structures to minimise any protection damage from side flashes to the structure. Agreement with the relevant utility should be sought prior to installation. In reality provided the structure is not smaller than 9m x 9m and the soil resistivity is less than ohm metres then the ring electrode will not need to be augmented with additional electrodes.

Maximum allowable cantilever for LPL I The above is based on 2 external, equally spaced down conductors and a Type A earthing arrangement.

Furse release 3rd edition of their renowned Guide to

Typical values of KS1 The table furee expands the relationship: Environmental ageing chamber for ammonia atmosphere ageing www. The acceptable or protective distance depends on the SPD technology, the type of system, the rate of rise of the incoming surge and the impedance of the connected loads.

B Mast A All yellow areas and the mast should be assessed for the need for air terminations Air termination required Mast Rolling sphere radius View on arrow A Figure 4. If this separation distance can be achieved, ie there is sufficient space on the roof then an air rod or suspended conductor should be installed see Figure 4.

Services This part, originally intended to complete the five-part set, will not now be published due to a lack of technical experts support at the international standards committee level.

However, in practice it is not possible nor indeed cost effective to go to such measures. Cloud to cloud discharge — inductive coupling Figure 1.