Effect of bending degree of down conductor on lightning current diversion in lightning protection system installation
The major role of protection against lightning are to secure structures and every component connected to it from lightning damage by directing the high currents and dispersed it to the ground safely. Lightning protection of structures and premises becomes crucial in order to provide the safety...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2015
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/67713/1/FK%202015%20119%20IR.pdf |
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| Summary: | The major role of protection against lightning are to secure structures and every
component connected to it from lightning damage by directing the high currents
and dispersed it to the ground safely. Lightning protection of structures and
premises becomes crucial in order to provide the safety and to ascertain that
the installation of Lightning Protection System (LPS) is reliable and comply with
the standards and specification assigned by the authority to assure the quality
of services. LPS have been designed deliberately to get the overall protection
via an external grid arrangement depends on the building constructions and
level of protection needed as per standard. A LPS is composed of three main
parameters which are the air termination network, the down conductor and the
earth termination. The down conductor is the medium to divert the lightning
current from the air termination to the earth termination system of protected
structures. This research focused on the down conductor and its effects when it
meets the bending part in the LPS installation. According to the standards and
specifications, the down conductor shall be installed as short and straight as
possible with particular attention shall be carried out eliminating sharp bends
and curves to provide a low impedance path between the air termination network
to the earth termination. However, due to the modern architecture and to fulfill
aesthetical requirement of the building, the bending seems unavoidable. The
aim of the research is to investigate and analyze the effect of the bending degree
of the down conductor in the LPS installation since no particular experiment has
been channeled away to this topic so far. Numerical (simulation) analysis has
been applied using Ansoft Maxwell software. The down conductor in concern for
the simulation is an Annealed Copper Tape that was injected with lightning
impulse current waveforms as per standard at the various bending degree.The
potentials and the fields involved are analyzed and the result was discussed in
comparison with the straight conductor and the standard. The main findings
conclude that the bending of the down conductor does give an effect where the
distribution properties of magnetic field, electric field and current densities can
be seen nonuniform along the conductor. The maximum value of magnetic field and current densities located at the vertex of the bent part and are influenced
by the bent angle. The magnetic field strength concentrated at the location of
the bent and getting stronger as the bending angle getting sharper which is could
lead to self-induced coupling and this behavior could cause current to directly
flow or short through it and ignite dangerous sparking during lightning strike. The
stronger the magnetic field, the greater will be the induced voltage produced
along the bent conductor compared with the straight conductor which is
hazardous in practice. The magnetic forced also may cause distribution of
current densities at the bent part nonuniform in the sectional area and form a
void. This phenomenon known as skin effect where current concentrated near
the surfaces of the conductor caused by electromagnetic induction and current
crowding that could reduce the cross sectional area for current conducting ability
to the ground. |
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