Lightning strokes, which amount to 200 kA or 300 kV, cause hazards on the equipment or location, so lightning protection is important for operation.
Allow us to start with the first note in regards to what is lightning and why lightning protection is really important. Principle phenomenon behind lightning is charges accumulated in the cloud and 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 in the surface, the breakdown occurs along with a “streamer” flows in the cloud for the earth.
A principal stroke takes place when the lightning hits the ability systems directly that the immense potential will cause destruction with the equipment or even the facility. On the other hand, an indirect stroke occurs from the lightning discharges inside the proximity in the power line or from electrostatic discharge about the conductor as a result of charged clouds.
The principle power system elements requiring lightning protection are power feeds, security systems, telephone lines, data and control systems and RF cables.
Ways of Lightning Protection. The rolling sphere strategy is utilized for identifying the complete keeping the lightning and surge protection devices at the equipment under operation.
Protection in the power line against direct strokes is thru a ground wire or protector tube. The former produces electrostatic screening, which is affected by the capacitances from the cloud to line and also the line to ground. Aforementioned forms an arc between the electrodes, causing gas deionisation.
Rooftop/Frame Protection. It’s interesting to make note of how the building and rooftop frame or cladding is preferably metal than insulation type.
Installing of a finial near the top of the ability tower really should have the absolute minimum distance of a single.5 m higher than the highest antenna or lights. This kind of rooftop or building frame is made of reinforced steel for defense purpose.
Wooden towers without downconductors may cause a fireplace hazard, since they route the incoming charges to ground. In principal, for non-metallic roofs, proper downconductors needs to be installed at the appropriate location and height.
Device Protection. Antenna lightning protection is provided through spark gap, the gas discharge tube and quad-wavelength shorted stub. The first method uses ball points so 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 last method works on the coax transmission line across the transmission line in order that system bandwidth is narrow.
A lightning arrester is a device offering lightning protection by regulating spark gaps. The device classification may range between rod gap, horn gap and valve type to metal oxide lightning arresters.
Earthing and Bonding Solutions. Now let’s talk of how earthing and bonding solutions for lightning protection needs to be afforded. The appearance of earth rods, terminals or clamps must be in ways 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 is not compensated. Again, the amount of interconnects and spacing should be designed per the lightning standards.
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