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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The designer will decide on the appropriate choice of SPD level as part of the risk procedure. Type of air termination system Number of down conductors kc Earthing arrangement Type A Earthing arrangement Type B km l n Single rod Wire Mesh Mesh 1 2 4 and more 4 and more, connected by horizontal ring conductors 1 0.
Annex NC helps to assess the amount of loss to a structure LX. Although BS advocates the use of reinforcing for equipotential bonding, BS EN emphasises on its importance. Therefore the furwe will have to wait until the next technical review, which is due to take place in guude KS4 relates to the rated impulse withstand voltage of the system. Similarly the withstand levels of telecommunication equipment is defined in specific industry standards, namely ITU-T K.
It is important to note that this British Standard will remain in force until at leastprior to this time the technical committee maintenance teams that compiled this standard will review and refine the body of this standard based on any further technical information and research that becomes available. Where adverse weather conditions occur, it may be prudent to inspect more regularly. As such the client will suffer a financial loss due to this loss of service as they are unable to sell their product into the open market.
Application of the rolling sphere to air rods in a non-isolated system s Figure 4. Minimum length of earth electrode 55 www. There are five Annexes and Annex E especially will be useful to anyone involved in the design, construction, gs and inspection of lightning protection systems.
Lightning current Grid-like spatial shields Large volume shields of LPZs are created by the natural components of a structure such as the metal reinforcements in walls, ceilings and floors, the metal framework and possible metallic roof and facades.
In line 6230 BSthe standard recommends a single integrated earth termination system for a structure, combining lightning protection, power and telecommunication systems. Again, four different air termination mesh sizes are defined and correspond to the relevant Class of LPS see Table 4.
The secondary effects of lightning can cause transient overvoltages by: BS EN part 1 is an introduction to the other parts of the standard and essentially describes how to design a Lighting Protection System LPS in accordance with the accompanying parts of the standard. Prior to this was BS CP, first published in On many occasions this is not practical to carry out.
So the collection area of flashes striking a line is determined by: If the other electrical services do not have an effective outer core screen, then consideration should be given to bonding to the nearest equipotential bonding bar, via Type II overvoltage SPDs.
Large area loops between mains power and data communication cable systems are, as a result of guice coupling, effective at capturing lightning energy and should therefore be avoided. This will minimise lightning currents within the structure. The following risks have been identified, corresponding to their equivalent type of loss. These SPDs also provide local protection by limiting overvoltages caused from switching operations, to safe levels.
A Guide to BS EN Protection Against Lightning_图文_百度文库
This is typically a screened room or, for mains power, at the sub-distribution board area. The use of computers, electronic process controls and telecommunications has exploded during the last two decades. However the live conductors within these service cables need to be equipotentially bonded at the service entrance through the use of SPDs. Similarly KMS see page 30, Probability of damage is a factor that is related to the screening effectiveness of the shields at the boundaries of the LPZs and is used to determine if a lightning flash near a structure will cause failure to internal systems.
If the reinforcing bars are connected for equipotential bonding or EMC purposes then wire lashing is deemed to be suitable.
The connection components are configured and tested to create the most onerous application. A range of pre-conditioned Furse components alongside an off-the-shelf original are shown in Figures 4.
Lightning Protection Standard BS EN 62305
Although lightning current discharges are a high frequency guids, at present most measurements taken of the earthing system are carried out using low frequency proprietary instruments.
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. Selection of the frse suitable LEMP protection measures is made using the risk assessment in accordance with BS EN taking into account both technical and economic factors.
The new standard reflects increased scientific understanding of lightning and its effects over the last twenty years, and takes stock of the growing impact of technology and electronic systems on our daily activities. Depending upon the consequences the designer may choose either of the following types of external LPS: Key and basic protection measures are: It will be buried in soil for many years so has to be totally dependable.
Furse release 3rd edition of their renowned Guide to Lightning Protection
To minimise the inductive voltage drop, lead lengths must be as short as possible ideally 0. 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.
Procedure for deciding the need for protection BS EN Figure 1 Identification of relevant losses The types of loss gulde could result from damage due to lightning must be identified for the structure.
However grid-like spatial shields are advisable where it is more practical, cost effective and useful to protect a defined zone or volume of the structure rather than several individual pieces of equipment.
Downstream SPDs those that are located within another lightning protection zone fitted fures part of a coordinated set to ensure operation of critical equipment should have a voltage protection level of no more than V 1. Thunderstorm days per year Td Flashes per km2 per year Ng 5 10 15 20 25 30 too 40 45 50 tl 60 65 70 75 80 85 90 95 0.
Furse release 3rd edition of their renowned Guide to
It therefore follows that spatial shielding should be planned at the early stages of a new build project as retro-fitting such measures to existing installations could result in significantly higher costs, practical installation implications with possible technical difficulties. For soil of resistivity ohm metres or less, the minimum length of electrode shall be 5m.
As a society, we are now heavily reliant on the continuous and efficient running of such systems. This is particularly important for the shield of LPZ 1, due to the partial lightning currents flowing through it. Additionally, all testing of the earthing system requirements should be fulfilled and all details logged in an inspection report.
Vertical air termination Concealed conductor Non-conventional air termination systems A lot of technical and commercial debate has raged over the years regarding the validity of the claims made by the proponents of such systems.