An Alternative Air Discharge Test Method using ESD Generator in Contact Discharge Mode

Abstract

It is well known that an air discharge immunity test method, which is specified in the International Electrotechnical Commission (IEC) standard, provides unstable test reproducibility owing to many factors such as the approach speed of an electrostatic discharge (ESD) generator, the curvatures of conductors inside equipment under test (EUT), climate conditions and the like. In this paper, to achieve stable testing repeatability, we propose an “alternative air discharge test method” using an ESD generator in its contact discharge mode to EUT covered with a non-conductive enclosure. In view of various curvatures of conductors inside the EUT, we use a spherical metal and a conical metal attached on an IEC recommended current injection target in lieu of an inner conductor of the EUT. Measurements of discharge currents are conducted with an ESD generator in contact discharge mode at test voltages from 5 kV to 15 kV through a fixed gap of 1 mm taken as a space distance between the inner conductors and the insulating enclosure surface. These measured current waveforms and their frequency spectra are compared with those for the air discharges. The dependence of the current peaks on test voltages is also investigated to reveal better testing repeatability.