A permanent short-circuit device for high-voltage power transmission applications: the device comprising an enclosure with a first fixed electrically conducting body and a second fixed electrically conducting body, each being connected to a respective conductor (30, 32) leaving the enclosure, the first body is elongated and has a first and a second surface (36, 38) on opposite sides of the first body, the second body having a first and a second surface (42, 44) on opposite sides of the second body, where the first surface of the first body faces the first surface of the second body and is separated therefrom by a gap with width d and the second surface of the first body is provided with explosives connected to a detonator for deforming the first body in the direction towards the first surface of the second body such that the first surface of the first body galvanically connects to the first surface of the second body across the gap, the first body having a first end at which it is connected to the corresponding conductor and a second opposite end where the first surface transitions into the second surface and having at least one detonation zone in the area where the explosives are applied, where the detonation zone begins at the second end, and stretches towards the first end and the amount of first body material between the first and second surfaces (36, 38) is lower in the detonation zone than in the rest of the first body, characterized in that the first and second bodies are tubes, with the first body being an inner body encircled by the second body, the first body comprises slits in the detonation zone, where the slits stretch along the longitudinal axis of the first body and with the second end of the first body being open. the device comprising an enclosure with a first fixed electrically conducting body and a second fixed electrically conducting body, each being connected to a respective conductor (30, 32) leaving the enclosure, the first body is elongated and has a first and a second surface (36, 38) on opposite sides of the first body, the second body having a first and a second surface (42, 44) on opposite sides of the second body, where the first surface of the first body faces the first surface of the second body and is separated therefrom by a gap with width d and the second surface of the first body is provided with explosives connected to a detonator for deforming the first body in the direction towards the first surface of the second body such that the first surface of the first body galvanically connects to the first surface of the second body across the gap, the first body having a first end at which it is connected to the corresponding conductor and a second opposite end where the first surface transitions into the second surface and having at least one detonation zone in the area where the explosives are applied, where the detonation zone begins at the second end, and stretches towards the first end and the amount of first body material between the first and second surfaces (36, 38) is lower in the detonation zone than in the rest of the first body, characterized in that the first and second bodies are tubes, with the first body being an inner body encircled by the second body, the first body comprises slits in the detonation zone, where the slits stretch along the longitudinal axis of the first body and with the second end of the first body being open.