Intergrates wave peak value of lightning surge current induced in a line and continuous time product as energy amount. 

SM-3A displays 3 ranges by input current value based on 10/200μs lightning surge waveform. 

Therefore, it estimates more current when longer than 10/200μ s waveform, less current when shorter than 10/200 μs waveform. 

There's the composition of a outside attachment CT and a plastic case built-in electronic counter. 

Current is powered by the lithium battery in the electronic counter. Non-maintainance usage.

Dimensions: W95×D158×H60 (mm) (Except projecting part of through terminal) / CT outer diameter φ50  inner diameter 15　thickness 28