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Dynamic Controls for Static

(December 2012) posted on Tue Feb 12, 2013

Learn about what static electricity is, the factors that affect it, and the methods available to counteract it.

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By Screen Printing's Solution Sourcebook

Battery effect The combination of many charged items can lead to extremely high charges. For instance, individual sheets of plastic with relatively low surface charges when stacked together can generate extremely high voltages.

Change in temperature As a material cools down it has a tendency to generate charge. The action of the cooling is to leave a net charge on the material throughout its entire volume. If the material is a very good insulator the internal (volumetric) static charge can be maintained for extremely long periods of time. However, over time this charge normally migrates to the surface, at which point it becomes a surface static charge.

Methods of elimination
The fundamental principle for neutralization of static charges is the same, regardless of the technique used. Where a material has a positive surface charge electrons must be delivered to the surface to bring the charge back into balance. Where the surface charge is negative the excess electrons must be removed from the surface to neutralize the charge.

Humidity Moisture on (or within) a material will tend to leach away static charges down to earth. For example, paper generally has relatively high moisture content and does not maintain particularly high levels of static. However, if the paper is particularly dry, static can become a severe problem.
Passive ionization The close proximity of a conductor to a charged object will tend to discharge it. For example, a carbon-fiber brush will reduce static charges in materials passed in close proximity to the brush.

Radioactive ionization Radioactive sources cause ionization of the surrounding air, thereby neutralizing surface static charges. A drawback of radioactive eliminators is the radioactive source loses its effectiveness over time and requires replacement on an annual basis.

Active electrical ionization Ionized air can be produced via high-voltage AC or DC, which can then be used to neutralize surface charges. The use of AC or DC systems is application dependent.


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