a review of electric utility’s experiences with polymeric insulators

A Review of Electric A Review of Electric Utility’s Experiences with Utility’s Experiences with

Polymeric InsulatorsPolymeric InsulatorsKhaled Y. Al-Soufi Khaled Y. Al-Soufi

Ibrahim O. HabiballahIbrahim O. Habiballah

KFUPM, Saudi ArabiaKFUPM, Saudi ArabiaDecember, 2004December, 2004

OutlineOutline

IntroductionIntroduction

International SurveyInternational Survey

County’s service ExperienceCounty’s service Experience

Laboratory Test MethodsLaboratory Test Methods

ConclusionConclusion


Gulf Council Countries (GCC) are extended Gulf Council Countries (GCC) are extended along the coast of the Arabian Gulf and along the coast of the Arabian Gulf and through vast desert areas through vast desert areas

These areas are affected by severe These areas are affected by severe weather conditions which are weather conditions which are characterized by high temperature, large characterized by high temperature, large daily and seasonal temperature variations daily and seasonal temperature variations and high humidity levels through the and high humidity levels through the summer months summer months


The severity and diversity of these The severity and diversity of these weather conditions affect the weather conditions affect the performance of the electrical network performance of the electrical network hardware, such as the insulatorshardware, such as the insulators


Various kind of polymers, such as silicone Various kind of polymers, such as silicone rubber, EPDM (Ethylene Propylene Dine rubber, EPDM (Ethylene Propylene Dine Monomer), EVA (Ethylene Vinyl acetate Monomer), EVA (Ethylene Vinyl acetate Copolymer) and PTFE (Poly Tetrafluoro Copolymer) and PTFE (Poly Tetrafluoro Ethylene) were used for outdoor insulation Ethylene) were used for outdoor insulation in different applications including in different applications including transmission/ distribution insulators, post transmission/ distribution insulators, post type insulators and hollow core types for type insulators and hollow core types for apparatus apparatus


A serious problem with polymeric A serious problem with polymeric insulators, however, is their insulators, however, is their sensitivity to atmospheric and sensitivity to atmospheric and electrical stresses in outdoor electrical stresses in outdoor applications which can lead to the applications which can lead to the aging phenomena of the polymeric aging phenomena of the polymeric insulator and may lead to reduction insulator and may lead to reduction in the useful life of the insulators in the useful life of the insulators


Selection of a polymeric insulator for Selection of a polymeric insulator for a given site must be based on careful a given site must be based on careful analysis and testing analysis and testing

The main objective of this paper is to The main objective of this paper is to present a thorough literature review present a thorough literature review and investigations of local and and investigations of local and international electric utility’s international electric utility’s experiences with polymeric experiences with polymeric insulators insulators


The paper will also present the major The paper will also present the major procedure needed to assess the procedure needed to assess the performance of such insulators in the performance of such insulators in the GCC area GCC area


Through the last three decades huge Through the last three decades huge amount of data collected about amount of data collected about polymeric insulator performance and polymeric insulator performance and utility service experiences utility service experiences

CIGRE, EPRI, Japanese manufacturer CIGRE, EPRI, Japanese manufacturer and research centers conducted and research centers conducted international surveys about utilities international surveys about utilities service experience with polymeric service experience with polymeric insulators insulators


The CIGRE working group dealing The CIGRE working group dealing with polymeric insulators distributed with polymeric insulators distributed questionnaire in 1987, with various questionnaire in 1987, with various questions on experience with questions on experience with polymeric insulators to many polymeric insulators to many electricity companies all over the electricity companies all over the world world


The major outcome regarding the The major outcome regarding the use of polymeric insulators: To use of polymeric insulators: To combat vandalism, easy combat vandalism, easy transportation and installation, anti-transportation and installation, anti-contamination capabilities, high contamination capabilities, high strength-to-weight ratio and for strength-to-weight ratio and for aesthetic appearance aesthetic appearance


CIGRE made another survey in 2000CIGRE made another survey in 2000

This survey indicated the findings of This survey indicated the findings of the previous Cigre survey and the previous Cigre survey and nominated silicone rubber material nominated silicone rubber material as the most widely used for as the most widely used for polymeric insulators in Africa, Asia, polymeric insulators in Africa, Asia, Australia, Canada, Europe, South Australia, Canada, Europe, South America and Middle East America and Middle East


EPRI of the USA has distributed EPRI of the USA has distributed questionnaire to the utilities in the questionnaire to the utilities in the USA in 1989USA in 1989

The survey indicated that the The survey indicated that the polymeric post insulators were used polymeric post insulators were used more frequently at the 115 kV and more frequently at the 115 kV and 138 kV levels, whereas polymeric 138 kV levels, whereas polymeric suspension insulators are most suspension insulators are most prevalent at 230 kV prevalent at 230 kV


Reasons cited by utilities for this Reasons cited by utilities for this early survey gave high percentage to early survey gave high percentage to combating vandalism, and then other combating vandalism, and then other reasons follow as experimenting and reasons follow as experimenting and light weight. light weight.


EPRI made another recent survey EPRI made another recent survey “Polymer Insulator Survey” in 2002 “Polymer Insulator Survey” in 2002

The results of the survey indicated The results of the survey indicated that the failure rate for all that the failure rate for all manufacturers that provided sales manufacturers that provided sales information was 1 in every 65,500 information was 1 in every 65,500 units sold units sold


Japan started a “Research and Japan started a “Research and Evaluation Program on Non-ceramic Evaluation Program on Non-ceramic insulators in October 1997, to insulators in October 1997, to evaluate the fundamental evaluate the fundamental performance of polymeric insulators performance of polymeric insulators and investigate their use status in and investigate their use status in Europe, North America, Australia Europe, North America, Australia


Reason for use: High percentage Reason for use: High percentage goes to easy installation, lightweight, goes to easy installation, lightweight, vandalism, contamination vandalism, contamination performance, easy maintenance, performance, easy maintenance, Cost, Strength, and Radio noise Cost, Strength, and Radio noise

About 80% of the responses About 80% of the responses indicated the interest in future indicated the interest in future utilization utilization


SEC-ERB, Saudi Arabia, adopted polymeric SEC-ERB, Saudi Arabia, adopted polymeric insulator, on trial basis, in three different insulator, on trial basis, in three different lines of 230 kVlines of 230 kV

The first line started on 1995 and was The first line started on 1995 and was affected by desert pollution affected by desert pollution

The second line started on 1996 and was The second line started on 1996 and was affected by semi-coastal pollution affected by semi-coastal pollution

The third line started on 1996 and affected The third line started on 1996 and affected by coastal and industrial pollutionby coastal and industrial pollution


The polymeric insulators presented The polymeric insulators presented excellent performance through the excellent performance through the period of data collection (1995 – period of data collection (1995 – 2001 2001

These lines behaved well without These lines behaved well without flashovers and didn’t need washing flashovers and didn’t need washing through the whole trial evaluation through the whole trial evaluation period period


Samples of these insulators were Samples of these insulators were subjected later to mechanical, subjected later to mechanical, electrical laboratory testing and electrical laboratory testing and material evaluationmaterial evaluation

The electrical and mechanical results The electrical and mechanical results proved the superior performance of proved the superior performance of these silicone rubber polymeric these silicone rubber polymeric insulators insulators


There were signs of minor There were signs of minor degradation but without effect on the degradation but without effect on the overall performance of these overall performance of these insulatorsinsulators

SEC-ERB considered the performance SEC-ERB considered the performance of the polymeric insulator of the polymeric insulator satisfactory and cost effective as it satisfactory and cost effective as it helps to decrease the maintenance helps to decrease the maintenance requirements requirements


Tunisian electrical company (STEG) Tunisian electrical company (STEG) erected more that 18 test stations erected more that 18 test stations distributed in representative area of the distributed in representative area of the country to collect data about insulator country to collect data about insulator performance performance

After five years in service, STEG confirmed After five years in service, STEG confirmed the satisfactory performance of the the satisfactory performance of the polymeric insulators on medium and high polymeric insulators on medium and high voltage lines voltage lines


Ageing aspects were noticed on the Ageing aspects were noticed on the polymeric insulators after 18 to 24 polymeric insulators after 18 to 24 months of services, which include months of services, which include discoloring and erosion discoloring and erosion

Silicone rubber sheds maintain Silicone rubber sheds maintain hydrophobicity features for longer hydrophobicity features for longer time than EPR or EPDM rubbers time than EPR or EPDM rubbers


Some of the units showed water–Some of the units showed water–tightness defects for the first tightness defects for the first generation insulators. Newer generation insulators. Newer versions were working fine versions were working fine

The alternate shed insulators (shed’s The alternate shed insulators (shed’s slope < 18slope < 18oo) more suitable for desert ) more suitable for desert and coastal areas and coastal areas


Powerlink Company is the operator of Powerlink Company is the operator of the transmission grid in the north-the transmission grid in the north-eastern Australian State eastern Australian State

They are using polymeric insulators They are using polymeric insulators since 20 years ago since 20 years ago


The main problem The main problem cause a worry for cause a worry for them is the bird them is the bird attacks which eat attacks which eat part of the part of the insulator and insulator and render it useless render it useless


Most of the laboratory tests tried to Most of the laboratory tests tried to check the aging mechanism of the check the aging mechanism of the insulator housing insulator housing

The IEC 1109 defined extensive The IEC 1109 defined extensive evaluation program for all parts of the evaluation program for all parts of the polymeric insulator polymeric insulator


The aging process and evaluation of the The aging process and evaluation of the shed material are addressed through shed material are addressed through lengthy testing technique of 1000 hours lengthy testing technique of 1000 hours and 5000 hours in a salt fog chamber and 5000 hours in a salt fog chamber

The insulator should be subjected to The insulator should be subjected to electrical and weather parameters stress, electrical and weather parameters stress, as UV, humidity, heat, and rain in as UV, humidity, heat, and rain in systematic manner for the defined period systematic manner for the defined period


This This accelerated aging testaccelerated aging test is trying is trying to simulate the effect of the harsh to simulate the effect of the harsh environment combined with environment combined with electrical arcing stress electrical arcing stress

The The rotating wheel testrotating wheel test is intended is intended to evaluate the shed material and to evaluate the shed material and the interfacing between sheds, rod the interfacing between sheds, rod and end fittings and end fittings


The The inclined plane testinclined plane test is intended to is intended to evaluate the resistance of the material evaluate the resistance of the material against tracking and erosion under HV against tracking and erosion under HV stressstress

Field inspectionField inspection provides clear reference provides clear reference picture to simplify in-service inspection picture to simplify in-service inspection for the utilities for the utilities


ESDD and NSDD measurements.ESDD and NSDD measurements. include timely measurement for the include timely measurement for the level of contamination on the level of contamination on the insulator surfaceinsulator surface

Contact angle measurement: Contact angle measurement: provides quick evaluation for the provides quick evaluation for the hydrophobicity conditions of the hydrophobicity conditions of the insulator surface insulator surface


Polymeric insulators have proved Polymeric insulators have proved itself in many locations through the itself in many locations through the worlds as very good insulator against worlds as very good insulator against contamination contamination

Silicone rubber insulating material is Silicone rubber insulating material is considered through laboratory considered through laboratory evaluation and field experience as evaluation and field experience as the most suitable for HV application the most suitable for HV application in harsh environment in harsh environment


The construction of the polymeric The construction of the polymeric insulator, type of shed material, end insulator, type of shed material, end fitting, fiber glass rod and fitting, fiber glass rod and manufacturing process are decisive manufacturing process are decisive factors in the overall insulator factors in the overall insulator performance performance

The GCC weather conditions are very The GCC weather conditions are very harsh and require careful selection harsh and require careful selection for the polymeric insulator for the polymeric insulator


There is clear need to adopt short There is clear need to adopt short and long term evaluation methods and long term evaluation methods for the polymeric insulator in for the polymeric insulator in cooperation with researching cooperation with researching universities and testing laboratories universities and testing laboratories

a review of electric utility’s experiences with polymeric insulators

Documents

polymeric post insulators

use of polymeric insulators

polymeric insulatorskhaled

post type insulators

international surveys

kv international surveyreasons

early survey

previous cigre survey