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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If details such as the shield resistance of the shielded cable is known at the time of carrying out the calculation and in reality this is highly unlikely in most practical cases then a low value of KS3 may be assigned.
Lightning Protection Standard BS EN 62305
In a non isolated system, a catenary conductor huide be used to protect larger items of roof mounted equipment from a direct strike.
The protective angle method is suitable for simple shaped buildings.
In essence, structural lightning protection can no longer be considered in isolation, protection against transient overvoltages or electrical surges are integral to the new standards. The process for determining the risk of lightning inflicted damage to a structure and its contents, is somewhat involved when considering all the factors that need to be taken into account.
Furse release 3rd edition of their renowned Guide to
Protection of electronic systems from transient overvoltages can prevent: This is particularly the case for SPDs installed in parallel shunt on power guive. This doubling may occur if the equipment corresponds. For soil of resistivity ohm metres or less, the minimum length of electrode shall be 5m. Although R1, gulde of loss of human life concentrates on the effects that fire and explosion can have upon us, it does not highlight or cover in any detail the effects the electromagnetic impulse will have on equipment housed within the structure.
There are two types of storm clouds, which generate a static electrical charge, heat storms and frontal storms. 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. I and II III and IV 1 2 2 4 Lightning protection systems utilised in applications involving structures with a risk of explosion should be visually inspected every 6 months.
A Guide to BS EN Protection Against Lightning_图文_百度文库
Our interpretation of this clause when applied to Type A arrangement is that with the test link removed and without any bonding to other services etc, the earth resistance of each individual earth electrode should be measured. Protection of internal systems fo a structure can be very effectively achieved by the implementation of the LPMS measures detailed in BS EN This is often referred to as the dielectric withstand.
If direct bonding is not acceptable then suitably designed SPDs should be used. Alternatively, the structure in question may need both structural LPS and a fully coordinated rurse of SPDs to bring the risk below the tolerable level RT. Requirements for conductors and earth electrodes BS EN Requirements for a transient surge protection device: As the current attempts to flow, devastating transient overvoltages occur across the sensitive components of the equipment.
Its effectiveness is determined by its material and construction as well as by the frequency of the impinging electromagnetic wave. Spatial shielding defines a protected zone that may cover: This can be achieved with the use of a meshed earthing system. It lists down the conductor and earth electrode types suitable for lightning protection applications.
Furse release 3rd edition of their renowned Guide to Lightning Protection
However, in practice it is not possible or indeed guiee effective to go to such lengths. The separation rn s indicated on Figure 4. This type of event occurs with tall or exposed structures. Where the sphere touches the structure lightning protection would be needed. As a society, we are now heavily reliant on the continuous and efficient running of such systems. This is a significant deviation from that of BS Key and basic protection measures are: The be table gives an indication of how many fruse rods would be required to achieve 10 ohms or less for varying soil resistivities.
Earth electrodes in soil should be copper or stainless steel when they are connected to reinforcing steel embedded in concrete, to minimise any potential electrochemical corrosion. BS EN part 2 risk management approach, does not concentrate so much on the purely physical damage to a structure caused by a lightning discharge, but more on the risk of loss of human life, loss of service to the public, loss of cultural heritage and economic loss.
These shall be discussed further in this guide.
Nevertheless, a four-part suite of standards has been compiled under the reference number series. The air termination network can comprise any combination of the three systems described on page 37, External LPS design considerations.
Possible protection measures against equipment failure include: