Dependence of charge decay characteristics on charging parameters

The method of charge decay measurement in the new draft British Standard 'Methods for measurements in electrostatics' (BS 7506) uses a high voltage corona discharge to place a patch of charge on the material to be tested. The time for charge decay is obtained from observations with a fast response fieldmeter of the decrease in surface voltage as the deposited charge migrates away over and through the material. The paper reports on studies on the influence of corona exposure, initial peak voltage, position of the outer boundary and open and earthed backing on decay time values. Reasonable correlation is shown to the times for decay of triboelectric charge - and no correlation to resistivity values. The results clarify requirements for standard test procedures.