Abstract: The protective device applies to an installation comprising a rack in which are engaged modular functional elements interconnected by means of an interconnecting circuit provided at the back of the rack. It uses a connector element mounted on the rack and whose connection pins are electrically connected to conductors of the interconnecting circuit, and a protective module comprising a case accommodating protective circuits linked to connection members of a second connector element susceptible of connecting into the first connector element in order to provide a disconnectable electrical link between the conductors and the corresponding protective circuits. The invention applies notably to the protection of the electronic installations situated on board an aircraft.