Abstract: A surge current detection device 30 is detachably attached to a conductor 11 and detects a surge current entering the conductor 11. The surge current detection device 30 includes: a holder 40 releasably holding the conductor 11 via first and second holder bodies 40-1 and 40-2 facing each other; a magnetic force concentrating member 60 having a substantially U-shaped cross-section, the magnetic force concentrating member 60 being secured inside the holder 40 and concentrating a magnetic flux included in a magnetic field generated by the surge current entering the magnetic flux conductor 11 to a high density at a predetermined detection region; and a magnetic material sheet 70 secured inside the holder 40 in such a manner that the magnetic material sheet 70 is positioned at the detection region, the magnetic material sheet 70 detecting the surge current.

Abstract: A protection element (e.g., an arrester) protects a piece of equipment to be protected, from surge currents line terminals and an earth terminal. Surge current detection devices are provided on respective conductors connected to the arrester. Each of the surge current detection devices is to detect the surge current penetrated into a conductor for a short period of time, and includes a magnetic flux concentration member by which a magnetic flux produced by the penetrated surge current is concentrated in a given detection area at a high density, and a ferromagnetic material sheet positioned on the given detection area. The ferromagnetic material sheet includes a recording layer which is able to record and erase the penetration state of the surge current. A plurality of microcapsules are arranged in the recording layer, and each of the microcapsules contains a suitable liquid, and a plurality of magnetic particles suspended in the suitable liquid.

Abstract: A surge current detection device 30 is detachably attached to a conductor 11 and detects a surge current entering the conductor 11. The surge current detection device 30 includes: a holder 40 releasably holding the conductor 11 via first and second holder bodies 40-1 and 40-2 facing each other; a magnetic force concentrating member 60 having a substantially U-shaped cross-section, the magnetic force concentrating member 60 being secured inside the holder 40 and concentrating a magnetic flux included in a magnetic field generated by the surge current entering the magnetic flux conductor 11 to a high density at a predetermined detection region; and a magnetic material sheet 70 secured inside the holder 40 in such a manner that the magnetic material sheet 70 is positioned at the detection region, the magnetic material sheet 70 detecting the surge current.

Abstract: A protection element (e.g., an arrester) protects a piece of equipment to be protected, from surge currents line terminals and an earth terminal. Surge current detection devices are provided on respective conductors connected to the arrester. Each of the surge current detection devices is to detect the surge current penetrated into a conductor for a short period of time, and includes a magnetic flux concentration member by which a magnetic flux produced by the penetrated surge current is concentrated in a given detection area at a high density, and a ferromagnetic material sheet positioned on the given detection area. The ferromagnetic material sheet includes a recording layer which is able to record and erase the penetration state of the surge current. A plurality of microcapsules are arranged in the recording layer, and each of the microcapsules contains a suitable liquid, and a plurality of magnetic particles suspended in the suitable liquid.