Insulator Design for Desert & Harsh Environments ALBERTO PIGINI - - PowerPoint PPT Presentation

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Apr 06, 2023 204 likes •389 views

Insulator Design for Desert & Harsh Environments ALBERTO PIGINI INSULATOR DESIGN FOR DESERT AND HARSH ENVIRONMENT ALBERTO PIGINI CONTENT OF THE PRESENTATION INTRODUCTION FIELD EXPERIENCE ASSESSMENT OF POLLUTION SEVERITY

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Insulator Design for Desert & Harsh Environments

ALBERTO PIGINI

SLIDE 2

INSULATOR DESIGN FOR DESERT AND HARSH ENVIRONMENT ALBERTO PIGINI

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CONTENT OF THE PRESENTATION

INTRODUCTION
FIELD EXPERIENCE
ASSESSMENT OF POLLUTION SEVERITY
INSULATOR PERFORMANCE IN HARSH CONDITIONS
DESIGN FOR HARSH ENVIRONMENT
CONCLUSIONS

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INTRODUCTION

In harsh environment under AC and especially under DC pollution may

dominate the design

Accurate design is necessary to limit costly under and over design.
Accurate design is especially important for composites

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FIELD EXPERIENCE

«Standard» 53,7 mm/kV is not sufficient. Examples:

Saudi Arabia: better performance in AC with 86 mm/kV. Still some flashovers and

need of washing

Need of systematic line washing also reported from Iran Jordan , Algeria, Tunisia,

Egypt, Emirates, Israel, Morocco, Peru and Mexico

Still controversy on the possibility to partially solve theproblem with polymeric

insulators

Field experience confirm the need of an accurate design. For an accurate design the

site severity condition and the insulator performance are to carefully defined. A statistical design approach may help.

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ASSESSMENT OF POLLUTION SEVERITY Contamination degree very different in different areas depending on:

Location (eg. Distance form the sea)
Type of sand
Additiona Industrial pollution

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ASSESSMENT OF POLLUTION SEVERITY

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ASSESSMENT OF POLLUTION SEVERITY

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ASSESSMENT OF POLLUTION SEVERITY Need of pollution maps:

To take into account both ESDD and NSDD (type of

chemical)

Calibration by long duration campaigns by suitable

stations.

Specific measurements in areas of specific interest
For DC necessity of measurements on energized insulators

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ASSESSMENT OF POLLUTION SEVERITY Need of estimate of number of pollution events (as an example the range for Saudi Arabia between brackets) :

Fog days (0-64)
Rain days (5-31)
Very high humidity days (40-88)

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INSULATOR PERFORMANCE IN HARSH CONDITIONS

Insulator types carefully selected (aereofoil, antifog,

coated insulators, composite insulators).

perform tests on the insulator selected simulating the

expected contamination condition (non standard contamination).

For preliminary design reference to available

experimental data can be made.

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INSULATOR PERFORMANCE IN HARSH CONDITIONS

For preliminary design formulas are defined to take into account:

RUSCD for AC/DC solid layer and salt fog

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INSULATOR PERFORMANCE IN HARSH CONDITIONS

For preliminary design formulas are defined to take into account:

RUSCD for AC/DC solid layer and salt fog
Correction for insulator geometry
Correction for wettability conditions
SDD estimate starting from ESDD and NSDD

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DESIGN FOR HARSH ENVIRONMENT

AC cap and pin insulators. 10 pollution events, 100 insulators contaminated.

ESDD=1 mg/cm2, NSDD 0,1-1 and 10 mg/cm2

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DESIGN FOR HARSH ENVIRONMENT

AC cap and pin insulators. 100 insulators contaminated. ESDD=1 mg/cm2,

NSDD=10 mg/cm2, Number of pollution events: 1-10 and 100.

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DESIGN FOR HARSH ENVIRONMENT

AC cap and pin insulators. 100 insulators contaminated. ESDD=1 mg/cm2, NSDD=10

mg/cm2, 10 pollution events. Influence of hydrorepellency (black curve uncoated insulator with W=7), red curve coated but aged (W=6), violet curve coated with W=4.

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CONCLUSIONS

Service experience confirms that IEC general indications are not adequate for

desert-desert coastal environment

Pollution severity can reach extreme values in the examined region, varying however

site by site. Also the number of pollution events are very variable. Consequently an accurate pollution mapping is necessary for an optimized design.

The insulator type should be specifically selected and possibly tests should be carried
ut to assess the performance of the insulators simulating the application conditions.
Preliminary evaluation can be carried out by extrapolating available knowledge
For an accurate design a statistical approach is to be used as shown by a few

examples in the paper.