Analysis of winding stockroll potential

When a dielectric web is wound into a stockroll, the electrical potential of the stockroll can build to a very high value if the web carries a net electrical charge, such as from electrification by conveyance rollers. If the web has a somewhat conductive layer the stockroll potential will reach a limiting value due to conduction away from the stockroll. If the web has finite resistivity, a current will flow in the web, due to the potential gradient between the building stockroll and the last conveyance roller, and may be sufficient to limit the stockroll potential (SRP). The relationship between this limiting SRP and the conveyance parameters of web velocity, web conductivity, charge density on the moving web, and other parameters is discussed in terms of a model whose characteristics are derived and compared with measurements made on winding stockrolls in a laboratory. Experimental results that confirm the predictions of the model are presented. The level of net charge on the web before windup is found to influence the rate at which the equilibrium potential is approached, but does not affect the ultimate equilibrium potential of the stockroll