Analysis of winding stockroll potential [electrostatics]

A model for a winding stockroll of conductive material at dynamic equilibrium potential is described. The basic premise of the model is that at equilibrium the conductive and convective currents in the final web span must be equal and opposite at all points, so that the total current is zero. The result of this requirement is that the equilibrium stockroll potential is an exponential function of web resistivity, web velocity, capacitance to the ground of the final span, and the length of the final web span. This exponential relationship has a common V/sub 0/ of about 1300 V at a point closely following the last roller, for a particular web span. The predictions of the model are in very good agreement with experimental winding results in the range of web resistivities and velocities encountered in practice.<>