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Terminology – Technical terms related to lightning transformers

Term Explanation
Surge transfer rate (%) The transfer rate of surge voltage output on the secondary side when a lightning surge has been generated on the primary side of a lightning transformer.
Surge attenuation (dB) Irregular voltage attenuation of lightning surges, etc., on secondary side against primary side.
Voltage fluctuation rate (%) Percentage by which secondary side no-load voltage rises higher than the rated voltage.
Efficiency (%) Percentage of output against input, such as voltage and electrical power.
Lightning surge Unusually high momentary voltage caused by lightning.
Impulse A momentarily spiked waveform with an extremely short duration.
Surge impedance (Ω) Refers to resistance obtained when high frequency is applied. Lightning surges have steep waveforms and often include high frequency components.
ILK The number of thunderstorm days occurring in a single year.
Stepped leader An electrical discharge that descends towards the earth in a stepped fashion from a thundercloud.
Multiple lightning discharge Two or more lightning strikes from a single discharge.
Lightning protection system (LPS)

System used in order to protect buildings and equipment, etc., against lightning.

Includes external lightning protection systems and internal lightning protection systems.
External lightning protection system Comprising air termination systems, reduction lead systems, and earthing systems.
Internal lightning protection system All measures in addition to external lightning protection systems in order to lessen the electromagnetic effects on the buildings and equipment, etc., to be protected. Includes equipotential bonding and the maintaining of safe separation distances.
Safe separation distance The minimum distance between two conductors within the article to be protected, so as not to generate a dangerous spark discharge.
Equipotential bonding Within an internal lightning protection system, in order to lessen electropotential difference caused by lightning discharge among discrete conductive sections, by connecting these sections via a direct conductor or a surge protection device.
Ring grounding electrode A grounding electrode that forms a closed loop around a building, either on the surface of the ground or below it.
Common grounding, shared grounding A method using one grounding electrode for different grounding purposes. Shared grounding makes for good lightning countermeasures.
Mesh grounding Method of laying grounding conductors in a lattice pattern.
Combination waveform The waveform created by waveform generator applying a 1.2/ 50μs voltage impulse at both ends of an open circuit, or an 8/20μs current impulse across a short circuit.
Subscriber protective device Used to protect telephone and CATV subscribers and subscribed telephone equipment, etc., from irregular voltage.