Abstract:
Nano–oils comprising stable and dilute di
spersions of synthesized Graphene (Gr)
nanoflakes and carbon nanotubes (CNT) h
ave been experimentally observed for the
first time to exhibit augmente
d dielectric breakdown strengt
hs compared to the base
transformer oils. Variant nano–oils comp
rising different Gr and CNT samples
suspended in two different grades of transfo
rmer oils have yielded consistent and high
degrees of enhancement in the breakdown
strength. The apparent counter–intuitive
phenomenon of enhancing insulating caliber of fluids utilizing nanostructures of high
electronic conductance has been shown to be
physically consistent thorough theoretical
analysis. The crux mechanism has been pin
pointed as efficient charge scavenging
leading to hampered streamer growth and development, thereby delaying probability
of complete ionization. The mathematical an
alysis presented provides a comprehensive
picture of the mechanisms and physics of
the electrohydrodynamics involved in the
phenomena of enhanced breakdown strengths.
Furthermore, the analysis is able to
physically explain the various breakdown ch
aracteristics observed as functions of
system parameters, viz. nanostru
cture type, size distribution, relative permittivity, base
fluid dielectric properties, nanomaterial
concentration and nano–oil temperature. The
mathematical analyses have been extended to propose a physically and dimensionally
consistent analytical model to predict the
enhanced breakdown strengths of such nano–
oils from involved constituent material pr
operties and characteristics. The model has
been observed to accurately predict th
e augmented insulating property, thereby
rendering it as an extremely useful tool for efficient design and prediction of
breakdown characteristics of nanostructu
re infused insulating fluids. The present
study, involving experimental investigations ba
cked by theoretical analyses and models
for an important dielectric phenomenon such as electrical breakdown can find utility in
design of safer and more efficient high opera
ting voltage electrical drives, transformers
and machines.
