The magic of the conductors current density in the time and in the space

摘要

This paper outlines and simplifies a couple of composite quantities the “I2 t”, related to the let-through energy produced in a conductor by a current I and the “I l” related to the ohm voltage drop in the conductor, defining the load current torque. The current density δ=I/S in the two above mentioned quantities expressed as “δ2 t” and “δ l” characterizes, in a general way, the heating and the voltage drop of a conductor that is its intrinsic behavior to the flowing of a current. Steady density values support the sizing of conductors for their continuous operation in the time and their configuration in the load “space” of the system. Withstand densities, related to the short time duration of one second, define the cables behavior to overloads and the short-circuit currents that the cables are capable to withstand.