Dependency of the Transferred Charge of Provoked Discharges from Insulated Surfaces on Temperature and Humidity

The maximum transferred charge of provoked discharges from different insulating materials charged by spraying ions, rubbing or streaming liquids was investigated in the temperature interval -20degC to +45degC at a relative humidity between 5% and 75%. The results obtained did not correlate with the absolute humidity but with the surface resistance and the relative humidity. In the case of streaming fuel of low conductivity, the generated charge reached its maximum around 5degC and at a relative humidity below 10%. When rubbing or spraying ions on insulating plastic materials, the optimal temperature interval for all materials was between 20degC and 25degC and the optimal relative humidity below 10%. In the case of an investigated ceramic tile, chargeability and surface resistance strongly decreased with temperature and reached 0 nC at a surface resistance of about 1 x 10¹¹ Omega at 35degC even in dry climate. No charges could be observed in any trial above 0degC at a relative humidity exceeding 60%. Below the freezing point, charging was only observed in the case of streaming liquids, probably due to icing of the samples investigated.