Measurement of Static Electricity

Measuring the static electricity is important. It allows you to see if there is static present, its size and where it is being generated.

It was seen earlier that static electricity is actually a surplus or deficit of electrons which is measured in Coulombs. As it is not possible to measure the charge in a material in Coulombs, the electric field strength or surface voltage related to the static charge is measured. This is the accepted method of measuring static in industry.

The relationship between the field strength and voltage is that the former is the voltage gradient at any point.

The Fraser 710 Meters measure surface voltage. They use circuitry:

A: The voltage across this capacitor varies directly with the charge.

Using Q (charge) = C (capacitance) x V (voltage) the capacitance is set at the measuring distance of 100mm. This means that the charge Q varies directly with the voltage V.

Fraser meters are simple to use and very useful in analysing problems.

It is important to follow operating instructions when measuring static. The electric field behaves in unique ways and must be understood. One of the most interesting characteristics of the electric field, which is very important when trying to measure the charge is shown below.

It is important to follow operating instructions when measuring static. The electric field behaves in unique ways and must be understood. One of the most interesting characteristics of the electric field, which is very important when trying to measure the charge is described below.

Electric field:

• is a region of space in which electrical (Coulomb) forces act.
• every charged object is surrounded by an electric field.
• the field line run perpendicular to the material and show the direction in which the force acts.
• it can be coupled with other bodies with important consequences for measuring and neutralising the charge.

The electric field lines run perpendicular to the charged material when it is in open air. When the electric field is like this it is easy to make accurate and intelligent measurements.

When the charged material passes over a roller, the electric charge couples with the roller and seems to disappear. It is impossible to make an accurate measurement near the roller. The electric field "returns" when the material leaves the roller and so can be measured again.