Principles of Lightning and Surge Protection
Lightning strokes, which add up to 200 kA or 300 kV, cause hazards towards the equipment or location, so lightning protection is crucial for operation.
Why don't we start with your initial note to what is lightning and why lightning protection is really important. The basic phenomenon behind lightning is the fact that charges accumulated through the cloud and also the earth are equal and opposite. This forms a non-uniform potential gradient surface in mid-air. When the gradient is larger as opposed to potential with the surface, the breakdown occurs plus a "streamer" flows from your cloud towards earth.
A primary stroke happens when the lightning hits the energy systems directly that the immense potential may cause destruction of the equipment or the facility. On the other hand, an indirect stroke occurs from the lightning discharges from the proximity with the power line or from electrostatic discharge on the conductor as a result of charged clouds.
The primary power system elements requiring lightning protection are power feeds, home security systems, telephone lines, data and control systems and RF cables.
Methods of Lightning Protection. The rolling sphere method is used for identifying the exact keeping the lightning and surge protection devices at the equipment under operation.
Protection of the power line against direct strokes is via a ground wire or protector tube. The previous produces electrostatic screening, that's impacted by the capacitances in the cloud to line and also the line to ground. The latter forms an arc involving the electrodes, causing gas deionisation.
Rooftop/Frame Protection. It is interesting to remember how the building and rooftop frame or cladding is preferably metal than insulation type.
Installation of a finial at the top of the power tower needs to have a minimum distance of just one.5 m across the highest antenna or lights. Such a rooftop or building frame is made of reinforced steel for cover purpose.
Wooden towers without downconductors might cause a fire hazard, while they route the incoming charges to ground. In principal, for non-metallic roofs, proper downconductors ought to be installed with the appropriate location and height.
Device Protection. Antenna lightning protection emerges through spark gap, the gas discharge tube and quad-wavelength shorted stub. The very first method uses ball points so that if a strike occurs, high potential forms between them along with the ground. The second method causes gas deionisation through arc formation between your electrodes. The final method utilizes a coax transmission line over the transmission line in order that system bandwidth is narrow.
A lightning arrester is really a device offering lightning protection by regulating spark gaps. The unit classification may range between rod gap, horn gap and valve type to metal oxide lightning arresters.
Earthing and Bonding Solutions. Now let us discuss how earthing and bonding solutions for lightning protection must be afforded. The design of earth rods, terminals or clamps needs to be in such a way to route the incoming transients to earth to minimise step and touch potentials. The geometric measurements chosen should adhere to the IEEE and NFPA standards. Any earthing system really should have proper bonding, as ground potential rise can not be compensated. Again, the quantity of interconnects and spacing ought to be designed per the lightning standards.
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