Resumen
The invention relates to a detector comprising a hollow cover or surrounding electrode (1) in which a second electrode (9) is connected concentrically to the first, said second electrode being formed by a magnet or magnetised bar for attracting ferromagnetic particles. According to the invention, when the number of particles increase to such a point that the electrodes come into contact with one another, the electric circuit closes indicating a possible fault in the controlled device. The body of the electrode or cover (1) is divided into different zones, namely: a front zone (2) through which the inner magnet bar electrode (9) can be seen and which is submerged in the lubricant to be controlled; a threaded intermediate zone (3) for connecting to the tank of the appliance; and a third output zone (4) for the contacts of the electrodes, including means for clamping the body of the cover onto the tank containing the lubricant.