Device for monitoring a current of a primary conductor with respect to a predetermined current threshold, and related trip assembly and switching device

A device for monitoring a current in a primary conductor with respect to a predetermined current threshold, comprising: - a magnetic circuit associable to the primary conductor and comprising a fixed part and an element which can rotate about a rotation axis; - at least one spring operatively connected to the rotating element for keeping it in a first position, the spring being elastically deformable along a linear axis; and - sensing means operatively associated to the magnetic circuit. The magnetic circuit is configured in such a way that the rotating element rotates from the first position to a second position when the current in the primary conductor exceeds the predetermined current threshold, so as to at least reduce one or more air gaps between the rotating element and the fixed part and to elongate the spring from a first length to a second length. The sensing means are configured for generating an output electrical signal caused by the rotation of the rotating element from the first position to the second position. The at least one spring is operatively connected to the rotating element in such a way to tilt towards the rotation axis moving above a surface of the rotating element which is transversal to the rotation axis, during the rotation of the rotating element from the first position to the second position.