Mathiasen Damgaard posted an update 3 years, 8 months ago
Lightning strokes, which total 200 kA or 300 kV, cause hazards for the equipment or location, so lightning protection is crucial for operation.
Allow us to focus on the first note in regards to what is lightning and why lightning protection can be so important. Principle phenomenon behind lightning is charges accumulated through the cloud and the earth are equal and opposite. This forms a non-uniform potential gradient surface up. If the gradient is larger as opposed to potential from the surface, the breakdown occurs and a "streamer" flows from the cloud towards the earth.
An immediate stroke takes place when the lightning hits the ability systems directly the immense potential will cause destruction with the equipment or facility. On the other hand, an indirect stroke is carried out in the lightning discharges inside the proximity with the power line or from electrostatic discharge around the conductor as a result of charged clouds.
The main power system elements requiring lightning protection are power feeds, home alarm systems, telephone lines, data and control systems and RF cables.
Strategies to Lightning Protection. The rolling sphere technique is employed for identifying the precise placement of the lightning and surge protection devices nearby the equipment under operation.
Protection from the power line against direct strokes is by a ground wire or protector tube. The first kind produces electrostatic screening, which is impacted by the capacitances from the cloud to line and the line to ground. Rogues forms an arc involving the electrodes, causing gas deionisation.
Rooftop/Frame Protection. It is interesting to remember the building and rooftop frame or cladding is preferably metal than insulation type.
Installing a finial on top of the power tower must have a minimum distance of just one.5 m over the highest antenna or lights. Such a rooftop or building frame is constructed of reinforced steel for cover purpose.
Wooden towers without downconductors could potentially cause a fire hazard, as they route the incoming charges to ground. In principal, for non-metallic roofs, proper downconductors should be installed on 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 1st method uses ball points to ensure if your strike occurs, high potential forms bewteen barefoot and shoes and the ground. The 2nd method causes gas deionisation through arc formation between your electrodes. The final method runs on the 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’s talk of how earthing and bonding solutions for lightning protection must be afforded. The style of earth rods, terminals or clamps should 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 should have proper bonding, as ground potential rise cannot be compensated. Again, the quantity of interconnects and spacing needs to be designed per the lightning standards.
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