IEEE Electrical Insulation Magazine
In this article, the feasibility of using
time and frequency domain dielectric
spectroscopy techniques to monitor
the condition of oil-impregnated
paper (OIP) condenser bushings is
ushings are essential elements of many power equipments,
including circuit breakers, capacitors, reactors, etc. Both
high- and low-voltage windings are insulated from the core and
from each other, and leads are brought out through insulating
bushings. The two basic bushing designs are non-graded and
capacitance-graded. The former is the simplest and the oldest.
Capacitance graded bushings are available in four technologies:
Resin Bounded paper (RB), Oil-Impregnated Paper (OIP), Resin
Impregnated Paper (RIP) and Epoxy Resin Impregnated Paper
(ERIP). OIP bushing, developed in the 1920s, is one of the most
common types . About 80% of all bushings in use today are
of the OIP type.
Explosive failure often follows bushing deterioration/degrada-
tion, frequently resulting in catastrophic and expensive failure of
a transformer and heavy damage to adjacent equipment. Accurate
monitoring of the condition of bushings in service is therefore
of vital importance.
At present, routine maintenance tests most often used for
checking the condition of bushings involve visual inspection and
power factor/capacitance tests at line frequency . The need to
test power system insulation non-destructively and reliably in
the ﬁeld has driven the development of diagnostic tools based on
changes in the dielectric properties of the insulation –.
In this article, the feasibility of using time- and frequency-
domain dielectric spectroscopy measurements to monitor the
fabrication of OIP condenser bushings is discussed. Such mea-
surements have been made on a laboratory OIP bushing model.
The manufacturing process consisted of three stages, namely
fabrication, drying and impregnation. Short-circuit between some
of the condenser layers has also been simulated.
Dielectric Spectroscopy Techniques
The fundamental theories behind dielectric measurements are
well known , , . Dielectric phenomena are discussed
in Jonscher’s publications . However, to facilitate interpreta-
tion of the measurements presented in this paper, a short review
Dielectric Spectroscopy Techniques as
Quality Control Tool: A Feasibility Study
Oil-Impregnated Paper (OIP) condenser bushings, dielectric spectroscopy, time
domain, frequency domain.
A. Bouaïcha and I. Fofana
Canada Research Chair, tier 2, Insulating Liquids
and Mixed Dielectrics for Electrotechnology
(ISOLIME), Université du Québec à Chicoutimi,
Chicoutimi, Qc, Canada.
International Research Centre on Atmospheric
Icing and Power Network Engineering (CenGivre),
Université du Québec à Chicoutimi, Chicoutimi, Qc,