Lightning strokes, which total 200 kA or 300 kV, cause hazards on the equipment or location, so lightning protection is important for operation.
Let us start with the initial note to what is lightning and why lightning protection is so important. The basic phenomenon behind lightning is the fact that charges accumulated through the cloud and the earth are equal and opposite. This forms a non-uniform potential gradient surface via a flight. In the event the gradient is bigger compared to the potential from the surface, the breakdown occurs and a "streamer" flows through the cloud for the earth.
A principal stroke happens when the lightning hits the power systems directly that the immense potential can cause destruction in the equipment or perhaps the facility. In comparison, an indirect stroke is carried out in the lightning discharges in the proximity in the power line or from electrostatic discharge about the conductor due to the charged clouds.
The primary power system elements requiring lightning protection are power feeds, alarm systems, telephone lines, data and control systems and RF cables.
Methods of Lightning Protection. The rolling sphere method is employed for identifying the exact placement of the lightning and surge protection devices nearby the equipment under operation.
Protection in the power line against direct strokes is through a ground wire or protector tube. The first sort produces electrostatic screening, that's impacted by the capacitances from the cloud to line along with the line to ground. Aforementioned forms an arc between the electrodes, causing gas deionisation.
Rooftop/Frame Protection. It really is interesting to notice how the building and rooftop frame or cladding is preferably metal than insulation type.
Installation of a finial near the top of the electricity tower should have the absolute minimum distance of merely one.5 m higher than the highest antenna or lights. This type of rooftop or building frame is constructed of reinforced steel for cover purpose.
Wooden towers without downconductors could cause a fire hazard, as they route the incoming charges to ground. In principal, for non-metallic roofs, proper downconductors must 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 initial method uses ball points to ensure that in case a strike occurs, high potential forms with shod and non-shod and also the ground. The next method causes gas deionisation through arc formation involving the electrodes. The past method runs on the coax transmission line through the transmission line so 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's find how earthing and bonding solutions for lightning protection needs to 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 abide by the IEEE and NFPA standards. Any earthing system really should have proper bonding, as ground potential rise is not compensated. Again, the quantity of interconnects and spacing should be designed per the lightning standards.
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