Welcome to Tea with DidiMay 21, 2019
Eaton Clark posted an update 3 months, 2 weeks ago
Lightning strokes, which total 200 kA or 300 kV, cause hazards towards the equipment or location, so lightning protection is vital for operation.
Let us commence with your initial note about what is lightning and why lightning protection is really important. The essential phenomenon behind lightning is that charges accumulated in the cloud along with the earth are equal and opposite. This forms a non-uniform potential gradient surface via a flight. Once the gradient is bigger than the potential of the surface, the breakdown occurs as well as a "streamer" flows in the cloud towards the earth.
A direct stroke occurs when the lightning hits the electricity systems directly the immense potential can cause destruction from the equipment or facility. As opposed, an indirect stroke is carried out in the lightning discharges in the proximity from the power line or from electrostatic discharge for the conductor due to the charged clouds.
The principle power system elements requiring lightning protection are power feeds, security systems, telephone lines, data and control systems and RF cables.
Strategies to Lightning Protection. The rolling sphere technique is utilized for identifying the complete keeping the lightning and surge protection devices at the equipment under operation.
Protection of the power line against direct strokes is thru a ground wire or protector tube. The former produces electrostatic screening, which can be suffering from the capacitances in the cloud to line as well as the line to ground. Aforementioned forms an arc relating to the electrodes, causing gas deionisation.
Rooftop/Frame Protection. It can be interesting to notice how the building and rooftop frame or cladding is preferably metal than insulation type.
Installing of a finial at the top of the ability tower really should have a nominal amount distance of just one.5 m above the highest antenna or lights. A real rooftop or building frame is constructed of reinforced steel for protection purpose.
Wooden towers without downconductors might cause a hearth hazard, as 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 initial method uses ball points to ensure if the strike occurs, high potential forms together and also the ground. The 2nd method causes gas deionisation through arc formation involving the electrodes. The very last method uses a coax transmission line through 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 us discuss how earthing and bonding solutions for lightning protection should be afforded. The style of earth rods, terminals or clamps ought to be in ways 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 cannot be compensated. Again, the amount of interconnects and spacing needs to be designed per the lightning standards.
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