• Sanford Callesen posted an update 2 years, 4 months ago

    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 original note about what is lightning and why lightning protection can be so important. The basic phenomenon behind lightning is that charges accumulated through the cloud along with the earth are equal and opposite. This forms a non-uniform potential gradient surface up. In the event the gradient is greater compared to the potential of the surface, the breakdown occurs and a "streamer" flows in the cloud towards earth.

    A direct stroke happens when the lightning hits the energy systems directly that this immense potential will result in destruction from the equipment or perhaps the facility. In contrast, an indirect stroke occurs from the lightning discharges within the proximity from the power line or from electrostatic discharge on the conductor as a result of charged clouds.

    The key 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 used for identifying the complete positioning of the lightning and surge protection devices close to the equipment under operation.

    Protection in the power line against direct strokes is thru a ground wire or protector tube. The previous produces electrostatic screening, which can be suffering from the capacitances from the cloud to line and also the line to ground. The second forms an arc between your electrodes, causing gas deionisation.

    Rooftop/Frame Protection. It’s interesting to make note of that the building and rooftop frame or cladding is preferably metal than insulation type.

    Setting up a finial near the top of the power tower should have a nominal amount distance of a single.5 m higher than the highest antenna or lights. This type of rooftop or building frame is made from reinforced steel for protection purpose.

    Wooden towers without downconductors may cause a fire hazard, since they route the incoming charges to ground. In principal, for non-metallic roofs, proper downconductors ought to be installed in 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 to ensure if the strike occurs, high potential forms with shod and non-shod as well as the ground. The second method causes gas deionisation through arc formation relating to the electrodes. The last method works on the coax transmission line across the transmission line to ensure system bandwidth is narrow.

    A lightning arrester is often a device offering lightning protection by regulating spark gaps. The device classification may range from rod gap, horn gap and valve type to metal oxide lightning arresters.

    Earthing and Bonding Solutions. Now learn about how earthing and bonding solutions for lightning protection must be afforded. The design 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 conform to the IEEE and NFPA standards. Any earthing system must have proper bonding, as ground potential rise cannot be compensated. Again, the number of interconnects and spacing should be designed per the lightning standards.

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