Polymeric Insulator Materials for HVDC: Important Properties, Test - - PowerPoint PPT Presentation

Polymeric Insulator Materials for HVDC: Important Properties, Test Methods & Challenges for Standardization

JENS SEIFERT

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Mini Conference 9

Polymeric Insulator Materials for HVDC: Important Properties, Test Methods & Challenges for Standardization

Jens M. Seifert Lapp Insulators, BU LIKE GERMANY

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Results of D1.27 Brochure No. 611 “DC Tracking & Erosion Test”

DC vs. AC Test Voltage Idea: Development Approach based on IEC 60587 “Inclined Plane Test”

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Development Approach based on IEC 60587 “Inclined Plane Test””

mass loss, erosion depth, erosion length

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Investigation of Electrode Shape and Quality:

Development Approach based on IEC 60587 “Inclined Plane Test””

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Development Approach based on IEC 60587 “Inclined Plane Test”

Investigation of Electrolyte Flow Rate:

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Development Approach based on IEC 60587 “Inclined Plane Test”

Investigation of Corrosion Effects (Electrodes): 0.05 g dissolved Fe2+ by 180 C charge (Coulomb‘s law) simulated by adding to the eletrcolyte:

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Development Approach based on IEC 60587 “Inclined Plane Test”

Round Robin Test (Specification):

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Development Approach based on IEC 60587 “Inclined Plane Test”

Round Robin Test Results „PASS/FAIL“:

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Development Approach based on IEC 60587 “Inclined Plane Test”

RRT Results: „EROSION DEPTH“

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Comparison of „TEST SEVERITY“:

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DC-IPT as investigated can not be recommended for the base of an IEC standard CONCLUSIONS:

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Retention of Hydrophobicity – Why is this property important?

HC=1

HC=1 HC=6

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Retention of Hydrophobicity - “Dynamic Drop Test (DDT)” (Electra 272/03)"

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Retention of Hydrophobicity - “Dynamic Drop Test (DDT)” (Electra 272/03)

Investifation of surface topology: Specification for RRT: RZ = 5µm by means of special moulds and sandblasting Target: Explore and define a surface topology and roughness in order to achieve reasonable time to loss of HY with good reproducibility

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Retention of Hydrophobicity - “Dynamic Drop Test (DDT)” (Electra 272/03)

 High Scatter! Results of „explorative“ RRT for AC and DC stress: Weibull 63% Quantilles and 95% CI

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• DDT is a promising test method for evaluating the retention of HY
• Different materials and their performances can be distinguished
• Reasonable test parameters for „short time test“ have been defined
• Surface roughness RZ shall be 5 µm by means of sandblasting of moulds
• High scatter in time to failure is still a weak point
• Additional (larger) RRTs shall be conducted with different kinds of materials and 5-10 labs
• The work is continued in D1.58 in order to improve the test specification and test setup

Conclusion and further recommendations:

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Applicability and Reference to HVDC Composite Insulators:

Composite Insulators

• Comparison of Laboratory Tests and Field Ageing
• Design and Service Performance Reviews (Case Studies)
• Design & Standardisation Approaches for HVDC (IEC 60815-4)

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Applicability and Reference to HVDC Composite Insulators:

Typical Design of Generation III Composite Insulator

In DC applications 250-600 kV for more than 36 years

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1000h Salt Fog Testing (CN Std.) D/L T 864 -2004

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1000h Salt Fog Testing (CN Std.) D/L T 864 -2004

Well selected materials and designs pass the CN 1000 h std. test

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5000h DC Multi-Stress Test

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Design Approach AC and DC

CIGRE Technical Brochure No. 518

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Design Rules DC

CIGRE Technical Brochure No. 518

Why? Different electro-dynamical Characteristics of partial arcs AC: small p, small s, small s/p DC: large p, large s limited s/p  1.0 Normal distance p1 and p2 Large distance p1 and p2

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Design Rules DC

CIGRE Technical Brochure No. 518

AC DC AC: small p, small s, low s/p DC large p, large s limited s/p Normal distance between p1 and p2 larger distance between p1 and p2 NEW IEC 60815-4: Prague 2015 TC 36 WG11

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Case #1: 500 kV Pacific Intertie (USA)

36 years very positive experience with HTV Silicone Rubber Composites

Dual pole

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Case #1: 500 kV Pacific Intertie (USA) - Design Review

Design Pacific Intertie CD`=25.7 mm/kV

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Case #2: 533 kV Cabora Bassa - Apollo (SA) - Design Review

38 years very positive experience with HTV Silicone Composites

2 Mono Poles

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Case #2: 533 kV Cabora Bassa - Apollo (SA) - Statistical Design Approach

Re-Insulation 2013: 6800 glass disk strings were exchanged by composites, with CD`=35 mm/kV @ 4700 mm connection length

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Pollution Performance Curves

AC DC DC Silicone Composites

?

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IEC 60815 Statistical Method based on Pollution Performance Curves

AC DC DC Silicone Composites

?

400 kV HVDC Design for New Lines in Germany High design efficiency, optimum CD` and length selection!

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IEC 60815-4 (New) – Emprical Method „HTM“ Non-„HTM“

Based on best practice and correction factors (longer insulators)

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Conclusions on DC Material Tests

• Tracking & Erosion Resistance (T&E) and Retention of Hydrophobicity under DC voltage

stress were recognized by CIGRE as important properties for further standardisation

• With the results of a RRT („Feasibility Study“) performed by CIGRE WG D1.27 it is not

recommended to develop a DC T&E test based on the „Inclined Plane Test Method“

• The Dynamic Drop Test (DDT) has been evaluated positively in order to assess the

Retention of Hydrophobicity of polymeric materials

• The DDT method will be further investigated and developed by CIGRE WG D1.58
• Hydrophobicity is a very important property for the performance of DC Insulators

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Conclusions on DC Composite Insulators

• No Tracking & Erosion failures have been reported under DC voltage stress in service. Justification of

a T&E DC test is not given from relevance point of view. The results of this material test are not reflecting the positive experiences made in service

• Artifificial Ageing tests (1000 h, 5000 h, wheel test) under DC voltage stress are passed by composite

insulators with good design and well selected materials

• The hydrophobicity has a very positive impact on the life-time and performance of DC composite

insulators

• Very positive long-term service experiences exist with HTV silicone material (>30 years)
• Standardisation of housing profile and CD selection process is almost completed (IEC 60815-4):

Empirical and Statistical Method

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