Lightning strikes

The primary advantages of mechanical scales are that they are relatively inexpensive in smaller capacities they do not need electrical power, enhancing thein portabiUty and they do not need to be protected from power line transients or lightning strikes. 

Vitreous silica (silica glass) is essentially a supercooled Hquid formed by fusion and subsequent cooling of crystalline silica. It is found ia nature ia fulgerites, ie, fused bodies resulting from lightning striking quart2 sand. 

Golde, R.H., Lightning surges on overhead disiribuii(m lines caused by direct and indirect lightning strikes. AIEE Transactions (Power Apparatus and Systemi. 437-447. June (1959) IRC. 56-HV AC Circuit Breakers. 

When equipment is exposed to direct lightning strikes Equipment connected directly to an overhead line, or even through a transformer, will fall into this category. Select the highest value of BIL and even then a surge protection will become necessary for critical installations. 

When equipment is shielded This is when it is installed indoors, like a generator or motor. Now it may be subject to only attenuated surges. One may now select a lower value of BIL. In most cases surge protection may not be essential for direct lightning strikes. 

These are only basic guidelines. It is difficult to define exposed or shielded equipment accurately. Equipment installed indoors may never be subject to lightning strikes or their transferences, but may be exposed to severe switching surges and require surge protection as for an exposed installation. There is no readymade formula by... 

Basically they are light-duty arresters and must be installed at locations that are not directly exposed to lightning strikes. 

These are typical figures and can be varied by the manufacturer to suit an application. To identify the suitability of the arrester on direct lightning strikes. 

The time of travel from the point the lightning strikes on the overhead lines to the arrester, considering a line length of approximately 420 km and speed of propagation of the surge as 0.3 km/,us,... 

Roussakis, N. 1988. The Hazard of an Oil Storage Tank Explosion from Lightning Strike at a Flare Stack. Technical Paper (May 1988). Westech Industrial Limited, Calgary, Alberta, Canada... 

C02-0030. When lightning strikes, some N2 reacts with O2 to generate NO, as shown in the following molecular picture. Describe how this picture illustrates the features of atomic theory. 

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