2015 ELEC3002 Electric Grounding and File Safety April 2016.pdf- Adobe Reader Ed
ID: 2291030 • Letter: 2
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2015 ELEC3002 Electric Grounding and File Safety April 2016.pdf- Adobe Reader Edit View Window Help 5 | / 5 -+ | 100% ToolsSignComment 10 o 02 0.005 0.002 0101 10 2 50 100 200 500 1000: 2000 5000 10000 20000 s0000 1200 Figure 2 Question 5 (20 marks) a) Briefly explain the difference between a lightning impulse and a switching impulse and state the standard value for these impulses according to IEC 60060-1 (6 marks) b) State three components of a lightning protection system according to IEC62305 (3 marks) Briefly explain the functions of air termination systems of a lightning protection system. (3 marks) c) d) With the aid of a suitable diagram, briefly explain three methods can be used to determine the arrangement and the siting of the air-termination systems (8 marks) 12:15 PM /2/2018Explanation / Answer
b) Three components of lightning Protection system according to IEC62305 are
External lightning protection system comprising of
(i) Air-Termination system
(ii) Down conductor system
(iii) Earth-Termination system(isolated lightning protection)
Internal Lightning Protection system Comprising of Lightnini equipotential bonding and separation of distance.
(c) Air Termination system (ATS)
There are three protection methods for implementing ATS are
(i) Mesh Method - Used for all types of flat roofs
(ii) Protection Angle method - used for finials and single masts and also has height limitations.
(iii) Rolling sphere method - This is the most common method used everywhere and it is very suitable for all the types of structures even in the most complicated geographical arrangements also. first the sphere is rolled up and over the building structure in all the possible directions. Wherever the sphere touches the structure, it represents a potential poin of strike on the structure. Air terminals are placed at all the potential points of strike. Its then rolled up over the structure and at the last time the sphere only touches the air terminals and not the structure.
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