Concepts of Lightning and Surge Protection
Lightning strokes, which amount to 200 kA or 300 kV, cause hazards for the equipment or location, so lightning protection is crucial for operation.
Let us begin with the initial note as to what is lightning and why lightning protection is indeed important. The basic phenomenon behind lightning is the fact that charges accumulated from your cloud and also the earth are equal and opposite. This forms a non-uniform potential gradient surface via a flight. Once the gradient is larger as opposed to potential from the surface, the breakdown occurs plus a "streamer" flows from the cloud towards earth.
An immediate stroke happens when the lightning hits the power systems directly that this immense potential may cause destruction of the equipment or perhaps the facility. As opposed, an indirect stroke is carried out in the lightning discharges in the proximity of the power line or from electrostatic discharge for the conductor due to charged clouds.
The principle power system elements requiring lightning protection are power feeds, home security systems, telephone lines, data and control systems and RF cables.
Types of Lightning Protection. The rolling sphere strategy is used for identifying the exact placement of the lightning and surge protection devices at the equipment under operation.
Protection with the power line against direct strokes is via a ground wire or protector tube. The first kind produces electrostatic screening, which is suffering from the capacitances in the cloud to line and also the line to ground. Rogues forms an arc between the electrodes, causing gas deionisation.
Rooftop/Frame Protection. It's interesting to notice how the building and rooftop frame or cladding is preferably metal than insulation type.
Installation of a finial towards the top of the energy tower must have the very least distance of 1.5 m over the highest antenna or lights. This type of rooftop or building frame is constructed of reinforced steel for cover purpose.
Wooden towers without downconductors may cause a hearth hazard, since they route the incoming charges to ground. In principal, for non-metallic roofs, proper downconductors must be installed at the appropriate location and height.
Device Protection. Antenna lightning protection is given through spark gap, the gas discharge tube and quad-wavelength shorted stub. The first method uses ball points so that if your strike occurs, high potential forms with shod and non-shod along with the ground. The other method causes gas deionisation through arc formation between the electrodes. The final method uses a coax transmission line across the transmission line in order that system bandwidth is narrow.
A lightning arrester is often a device offering lightning protection by regulating spark gaps. The unit classification may vary from 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 needs to be afforded. The appearance of earth rods, terminals or clamps should be you might say to route the incoming transients to earth to minimise step and touch potentials. The geometric measurements chosen should conform to the IEEE and NFPA standards. Any earthing system should have proper bonding, as ground potential rise can't be compensated. Again, the amount of interconnects and spacing should be designed per the lightning standards.
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