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New Concepts in Voltage Grading
Jens M. Seifert BU LIKE Lapp Insulators GmbH, Germany
New Concepts in Voltage Grading JENS SEIFERT New Concepts in - - PowerPoint PPT Presentation
New Concepts in Voltage Grading JENS SEIFERT New Concepts in - - PowerPoint PPT Presentation
New Concepts in Voltage Grading JENS SEIFERT New Concepts in Voltage Grading Jens M. Seifert BU LIKE Lapp Insulators GmbH, Germany Content Introduction Characteristics of Microvaristor/Epoxy Composite Computational Verification
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Content
- Introduction
- Characteristics of Microvaristor/Epoxy Composite
- Computational Verification (FEM Simulations)
- Experimental Verification
- Summary
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Content
- Introduction
- Characteristics of Microvaristor/Epoxy Composite
- Computational Verification (FEM Simulations)
- Experimental Verification
- Summary
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Introduction
Main Features for Bushing Improvement:
- Damping of High Local Electrical Field Stresses
no partial discharges proctect from accelerated material aging
- Compact Design less requirement of space
- Eco-Friendly Design less 𝐓𝐆𝟕 is required
- Economical Design less material cost
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Concept of Design
Realisation using non-linear field grading material: µVar/epoxy
a) conventional bushing b) compact bushing with µVar
𝐞𝟑 ≈ 𝟏. 𝟖𝐞𝟐
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Content
- Introduction
- Characteristics of Microvaristor/Epoxy Composite
- Computational Verification (FEM Simulations)
- Experimental Verification
- Summary
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µVar Filled Epoxy
Morphology of µVar Fillers: µVar functional particle:
- each particle has the non-linear property
- ZnO-particles with Sb-Bi interphase
- Semiconductor with respect to field stress
- Switching field stress depends on grain size
- f ZnO
- µVar powder require a carrier matrix
ZnO grain Sb-Bi interphase
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µVar Filled Epoxy
Electrical properties of µVar filled epoxy resin with diff. contents:
75 wt% is required
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µVar Filled Epoxy
Temperature influence:
no significant influence of temperature
thermal stable
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Content
- Introduction
- Characteristics of Microvaristor/Epoxy Composite
- Computational Verification (FEM Simulations)
- Experimental Verification
- Summary
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Modelling Setup
A Simulated 550kV Bushing: 2D FEM-Simulations:
- Based on EQS (Electro-quasi-
static) approximation
- Both capacitive and resistive
effects are considered
- Allow virtual prototypical
design with low cost
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Simulation Results
- 33.3 %
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Simulation Results
The length of the µVar/epoxy layer should not be too short!
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Simulation Results
The thickness of the µVar/epoxy layer has almost no influence
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Content
- Introduction
- Characteristics of Microvaristor/Epoxy Composite
- Computational Verification (FEM Simulations)
- Experimental Verification
- Summary and Outlook
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Experimental Setup
Test Setup in HV Laboratory (Lapp Insulators GmbH)
µVar/Epoxy layer
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Experimental Results
Partical discharge measurement
(according to IEC standard 60137)
Voltage (RMS) Partial Discharge Partial Discharge
nominal voltage (318 kV)
< 1pC < 1pC
test overvoltage (476 kV )
<5 pC <5 pC
test overvoltage (710 kV ) 1 min.
5.5 pC-126 nC 5.5 pC-126 nC
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Experimental Results
Temperature measurement
(using an infrared camera)
Voltage (RMS) Time Temperature Increase
nominal voltage (318 kV)
20 min. 0.3 °C
test overvoltage (476 kV )
10 min. 7 °C
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Experimental Results
Temperature measurement
(using an infrared camera)
Image of temperature increase after approx. 10 mintes. start: 23 °C end: 30.2 °C
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Content
- Introduction
- Characteristics of Microvaristor/Epoxy Composite
- Computational Verification (FEM Simulations)
- Experimental Verification
- Summary
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Summary
- The first compact bushing featuring with µVar/epoxy
component
- Microvaristor/epoxy composite with above 75 wt% has
an obvious nonlinearity
- Using µVar/epoxy layers in bushing are able to reduce
high electric field stress
- This approach allows to design the bushing compactly
(eco-friendly and economical design)
- Design of compact bushing featuring µVar/epoxy via
FEM has been successfully demonstrated
- Design via FEM confirmed by high-voltage tests
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