Measurement of partial discharges in hexane under DC voltage

The very few stages of the low-density region (LDR) at an electrode in hexane are recorded by high-magnification, high-speed photography and low-noise electronics to determine the relationship between the inception and growth of the LDR and the current. Observations of the initiation phase of the LDR are made by an image-preserving optical delay which permits photography of unpredictable events after their occurrence. The current is monitored by a special low-noise preamplifier which also provides timing signals to the photographic system. The current producing the LDR is in the form of a growing pulse train which is in contrast to the linear growth observed in the LDR. It is concluded that the same considerations which explained the absence of an LDR in nitrobenzene can be used to explain the initiation of the LDR in the present investigation