Abstract: This paper presents the experimental results of 11 kV
and 33 kV silicon composite insulators under artificial salt and urea
polluted conditions. The tests were carried out under different
seasons like summer, winter, and monsoon. The artificial pollution is
prepared by properly dissolving the salt and urea in the water. The
prepared salt and urea pollutions are sprayed on the insulators and
dried up for sufficiently large time. The process is continued until a
uniform layer is formed on the surface of insulator. For each insulator
rating, four samples were tested. The maximum leakage current and
breakdown voltage were measured. From experimental data,
performance of test specimen is evaluated by comparing breakdown
voltage and leakage current during different seasons when exposed to
salt and urea polluted conditions. From these results the performance
of the insulators can be predicted when they are installed in
industrial, agricultural, and coastal areas. The experimental tests were
carried out in the High Voltage laboratory using two stage cascade
transformer having the rating of 1000 kVA, 500 kV.
Abstract: An acoustic emission (AE) technique is useful for
detection of partial discharges (PDs) at a joint and a terminal section of
a cross-linked polyethylene (XLPE) cable. For AE technique, it is not
difficult to detect a PD using AE sensors. However, it is difficult to
grasp whether the detected AE signal is owing to a single discharge or
not. Additionally, when an AE technique is applied at a terminal
section of a XLPE cable in salt pollution district, for example, there is
possibility of detection of AE signals owing to creeping discharges on
the surface of electric power apparatus. In this study, we evaluated AE
signals in order to grasp what kind of information we can get from
detected AE signals. The results showed that envelop detection of AE
signal and a period which some AE signals were continuously detected
were good indexes for estimating state-of-discharge.