Stray Currents

—1. Currents induced in the ma of a metal either by being cut by a moving magnetic field or by moving in the field. These etrrents circle about within the metal, absorbing energy and converting it into heat. They are usually called eddy currents, and sometimes Foucault currents after a French experimenter who investigated them. Eddy currents are the cause of much lo of energy in dynamos, motors and transformers. To obviate them, iron cores of armatures and induction coils are laminated or built up of thin metal stampings, the plane of division being arranged to lie parallel to the lines of magnetic force and at right angles to the direction the induced currents would tend to flow. 2. Currents which leak away from a street railway system through the ground, following underground pipes and other buried conductors, disintegrating and otherwise damaging them by the electro-chemical action known as electrolysis.