Condition monitoring (CM) of electrical equipment is an important field in electrical engineering and a
considerable amount of research is dedicated to this field. Power cables are one of the most important parts
of any electrical network and the variety of techniques available for CM of electrical cables is therefore no
surprise. Electrical cables are exposed to operational and environmental stressors which will cause
degradation of the insulation material. The degradation will continue to the point where the cable fails.
Blackouts caused by failing cables will have an effect on the safety, efficiency and production of an
electrical network. It is therefore important to constantly monitor the condition of electrical cables, in order
to prevent the premature failure of cables. The research presented in this dissertation sets out to investigate
CM techniques for power cables and to design and implement a basic cable CM technique based on the
principles of partial discharge (PD) measurements.
A comprehensive literature study introduces the fundamental concepts regarding the CM of power cables.
The basic construction of electrical cables, as well as the variety of different types is researched in order to
lay a foundation for the research that follow. CM techniques for electrical equipment are investigated, with
the emphasis on techniques used on cables. Conducted research led to the decision to focus on CM by
means of PD measurements. PD as a phenomenon is investigated to be able to better understand the origins
and effects of discharge activity. From there the focus shifts to the available techniques for monitoring the
condition of electrical cables by means of PD measurements. The research conducted in the literature study
chapter forms the basis from which the rest of the study is conducted.
Simulation models were used to study PD characteristics. The models are derived from engineering and
mathematical principles and are based on the well-known three-capacitor model of PD. The simulations
were performed in order to study the effects of discharge activity. The designed simulation models allows
for a variety of PD characteristics to be studied. The simulations were performed in the MATLAB®
Simulink® environment.
The research conducted in the dissertation was used to design an elementary CM technique which can be
used to detect the presence of PD within electrical cables. The designed CM technique was used for the
practical measurement of PD data. MATLAB® programs were designed in order to analyse the PD data in
both the time- and frequency-domain. The analysis of the measured data revealed PD characteristics of the
test specimen used for the measurements. The designed CM is used for the detection of PD activity within
electrical cables and in combination with other techniques, may be used for complete CM of electrical
cables. The experimental setup which was used to take practical PD measurements adds another dimension
to the work presented in this dissertation. / MIng (Electrical and Electronic Engineering), North-West University, Potchefstroom Campus, 2015
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:nwu/oai:dspace.nwu.ac.za:10394/15701 |
| Date | January 2015 |
| Creators | Van Jaarsveldt, Johannes Hendrik |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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