Master Thesis Presentation

Saturday 8 April 2023University of Dar es Salaam 1

M.Sc. Electrical Power Engineering Thesis

Presentation @ Kijitonyama Campus

Date: 09-09-2010Time: 10h00

Saturday 8 April 2023 University of Dar es Salaam 2

Title of the Thesis

Non-ceramic Insulators In Coastal Tropical Climates:

The Case Study of Tanzania Field Performance of Polymeric Insulators

and Dielectric Characteristics of Silicone Rubber and Epoxy Resin

Formulations

Saturday 8 April 2023University of Dar es Salaam 3

Presenter

Aviti Thadei B.Sc. (Hons) Electrical EngineeringM.Sc. (Student) By Research and Thesis AloneSupervised by Dr. A. L. Kyaruzi


Presentation Content

1. Introduction2. Problem Statement3. Objectives4. Work Carried Out5. Results6. Conclusions and Recommendations


Introduction

Polymer Insulators began to be used around 1970’s but suffered several problems. They were thought to be a solution to traditional ceramic insulators.

In Tanzania these insulators were first installed at Ruvu Chini Water Pump Station in 1974.

Till today, comparing with ceramics, NCIs are still very young.


Introduction

Issues with polymeric insulators• They offer better pollution

performance than ceramics, but it changes with time

• They are lightweight and compact• Susceptible to arcing damage due to

FO• Susceptible to aging


Problem Statement

1. Limited study of NCIs aging and oxidation in Tanzania despite their increasing applicability

2. Limited information about dielectric properties of silicone rubber and epoxy resin formulations when joined


Objectives

The study addressed the mentioned problems above, by:

1. Evaluating aging2. Evaluating oxidation and chalking

indices3. Characterising: surface, volume and

dielectric loss


Work Carried Out

1. Reviewing many of past works on NCIs in Tanzania

2. Quantification of HC, contamination, aging and oxidation of field installed insulators

3. Measurements of surface, volume resistivity and dielectric loss of polymeric formulations


Results

Satisfactory field performance of Local utility insulators: the insulators are heavily contaminated. Some were eaten by rodents when stored in a warehouse before installation.


Results

Test polymeric insulatorsKimara feeder: a class I pollution level

site. Dust and colour changes are visible on all insulators. 1 (K3) insulator has good HC, others have HC up to 7. however, they are serving the line.

Tazara feeder: class II pollution level site. Insulators contaminated, otherwise serving the line with no reported problems.


Results

Ohio Street distribution line: insulators are in good condition serving the line.

Masaki substation: a site with marine salt contamination problems. An NCI flashed over in 2008 and was replaced with porcelain. Insulators are dust coated. This insulator had clear signs of deterioration. FTIR spectra revealed reduction of functional groups from parts with burn marks to those without. There is increase of oxidation and hydroxil groups.


Results

Wazo hill substation: area is impacted by marine winds and cement dust. The insulators are washed regularly, as a result no reported problems on the line.

Ruvu chini water pump station: where the oldest NCIs are found functioning though with shed fringes broken at points. All showed good HC.


Results

Ras Kiromoni Marine cable link to Zanzibar: there are few polymer cable terminations. All types of insulation suffer from salt contamination.

High voltage yard at UDSM: clean site, where stored insulators were hanged to sunlight. They accumulated dust in various degrees. Some exhibited changes of HC from those values before installation. FTIR results showed decrease of functional groups from bulk of one of the insulator.


Results

Reduction of more than 15% on one insulator qualify for its condemnation. Another showed increase of functional groups with a lot of silica. Another showed little changes with lots of virgin hydrocarbons and alky-silicone.


Results

Oxidation and Chalking IndicesOI varies linearly with CI.

Conductivity of insulator surfacesInsulator from Masaki showed higher conductivity than others.


Results

Ruvu Chini insulator with damaged shed


Results

Masaki substation failed insulator


Results

Resistivity results are affected by preparation and manufacturing method and duration of application of voltage

Surface resistivity measurements were problematic due to: inconsistencies in humidity, temperature, electrode contact points on the surface.


Results

Dielectric measurements: values dependent on manufacturing technique. Mixed relaxations for SIR and epoxy.


Conclusion

Severe pollution accumulation occurs on lower surface of insulator shed close to live end.

NCIs performance on the lines is satisfactory with exception of the one failed. Oxidation and Chalking is evident on test insulators.

Dielectric propersties of polymeric formulations is dependent on manufacturing method and ambient factors. There is observed mixed relaxations within the materials at ambient temperature.


Recommendations

Insulation upgrading will achieve reduced total life cylce cost of transmission and distribution lines, by allowing compactness, less ROW, less maintenence/replacement, etc.


Future works

Further research works can be done on:1. Online monitoring of service stresses2. Quantification of charging, memory,

and fringing effects on polymeric materials during measurements.

3. Characterising dielectric properties of tropical field aged insulators of Tanzania.


THANK YOU

Master Thesis Presentation

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Transcript of Master Thesis Presentation