S. Hole et al., MEASUREMENT OF SPACE-CHARGE DISTRIBUTIONS IN INSULATORS UNDER VERY RAPIDLY VARYING VOLTAGE, IEEE transactions on dielectrics and electrical insulation, 4(6), 1997, pp. 719-724
In this paper we describe a new instrument for real-time measurements
of space charge distributions in insulators submitted to rapidly varyi
ng voltages. It is illustrated with the pressure wave propagation meth
od but can also be adapted for use with the pulsed electro-acoustic me
thod. A new acoustic generator has been designed to produce high ampli
tude pressure pulses, at a high rate, and with good reproducibility. T
his generator, made of a thin transducer coupled with a waveguide and
a backing medium, responds with a pressure pulse when a step voltage i
s applied. A special sample holder with a signal decoupling circuit, a
nd a storage unit have been developed. The described instrument allows
for measurements at a rate of 3200 Hz. Its potentialities are illustr
ated by studying the evolution of space charge in polyethylene samples
stressed by both pulsed and 50 Hz ac voltages.