What are the Causes of Static Electricity in Manufacturing?

C is the capacitor function which stores the charge, like a battery. It is usually the surface of the material / product.

R is the charge relaxation ability of the material / system - usually a small current flow.  If the material is conductive the charge will escape to earth and so will not become a problem.  If the material is non-conductive, the charge cannot escape and so can become a problem.

The Spark Gap is the limit to the voltage build-up.

The charging current is the charge generated by the action of the product over a roller etc.

The Charging Current charges up the capacitor (i.e. the product), increasing its voltage V.  As the voltage increases, current flows through the resistor R.  An equilibrium will be reached where the charging current is equal to the current flowing through the resistor. (Ohms Law applies here: voltage = current x resistance)

A static problem arises when the product is able to store a sizeable charge and a high voltage is present. The static problem will show itself in the form of a spark, electrostatic repulsion/attraction or shocks to operators.

Polarity of the Charge

The static charge may be positive or negative.  For AC static eliminators and passive dischargers (brushes) the polarity of the charge is not usually important.