Protection of station equipment against lightning

Protection of station equipment against lightning over-voltages is usually effected, by voltage-limiting devices such as spark-gaps or surge diverters. When there is appreciable separation between two items of equipment a protective device located near one may not be effective in limiting the voltage at the other to a safe value. The paper is in two parts: in Part 1 the factors determining the most suitable location for the device and its range of protection are investigated, and it is shown that, except for terminal stations involving only one overhead line, the most effective position as on the equipment nearest the overhead line. It is also shown that the range of protection which determines whether more than one protective device is desirable is very dependent on the steepness of front of the over-voltage. The steepness is dependent on the attenuation due to corona during the passage of the over-voltage along the overhead line; this question is examined in Part 2.