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A winding roll on a slitter shows signs of high static. The crackling might be enough for your customer to notice. Will this roll be a problem? When is it worth your time to act?
While a small amount of static will not cause problems, we need a way to decide what level of static is "small." Since I am an engineer, I like to put numbers on things to help me decide what to do. There are at least three different types of instruments that we can use to measure static.
Electrostatic fieldmeters are the workhorse for diagnosing static problems.
Coulomb meters are used with Faraday cups to measure charge on small objects or film samples.
Non-contacting electrostatic voltmeters measure the surface potential of a film.
When I need to decide if I must take action to solve a static problem, first I reach for my electrostatic fieldmeter. Equation 1 is a "stake in the ground" for a "stoplight" action guideline.
Electrostatic fieldmeters respond to static charge on the film, and this is the...