New FEM model for thermal analysis of medium voltage fuses

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New FEM model for thermal analysis of medium
voltage fuses
Esther Torres, Angel Javier Mazón, Elvira
Fernández, Inmaculada Zamora
University of the Basque Country (UPV/EHU)
Juan Carlos Pérez
MESA Schneider Electric
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Contents

• Introduction
• Classification of high-voltage fuses
• Back-up fuse construction
• New FEM model for thermal analysis of MV fuses
• The Finite Element Method
• Development of models
• Simulation results
• Conclusions

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Introduction

• First form of protection used on electrical
  networks
• Simple and cheap devices
• Used for a wide range of voltage levels
• Operation based on the melting of
  current-carrying elements

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Classification of high-voltage fuses

• Non-current limiting fuses
• Expulsion fuses
• Liquid fuses
• Current-limiting fuses
• Back-up
• General purpose
• Full-range

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Back-up fuse construction
1 End cap 2 Ceramic tube 3 Star-core 4 Fuse
elements 5 Quartz sand 6 Thermal striker
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New FEM model for thermal analysis of MV fuses

• Fuse operation is a thermal process
• INTERRUPTION ? Melting of the fuse element
• STEADY STATE ? Thermal equilibrium
• IEC 60282-1 High-voltage fuses. Part 1
  Current-limiting fuses
• The fuse must be able to carry continuously the
  rated current without damage and without
  exceeding temperature limits (Table 6), at an
  ambient temperature not higher than 40ºC
• De-rating may be required when the temperature
  surrounding the fuse exceeds 40 C (Annex F)
• Simulation techniques as the FEM can reduce the
  need for testing to check compliance with
  standards

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New FEM model for thermal analysis of MV fuses
The FEM

• The FEM is a numerical method to solve general
  differential equations in an approximate manner
• The region is divided into smaller parts (finite
  elements) and the approximation is carried out
  over each element
• The matrix equations for the individual elements
  are calculated and combined to form the matrix
  equations for the entire system
• The resulting set of equations is solved to
  obtain the nodal values of the field variable

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New FEM model for thermal analysis of MV fuses
Steps

• Development of models Solid Edge
• One loop of the fuse elements around the
  star-core
• Complete MV fuse
• FEM analysis COSMOS Design Star
• Meshing
• Definition of physical properties Thermal
  conductivity
• Application of loads and boundary conditions
• Heat source Fuse elements
• Radiation and natural convection from the ceramic
  tube
• Simulation

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New FEM model for thermal analysis of MV fuses
Models
Model A
Model B
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New FEM model for thermal analysis of MV fuses
Meshing
Model A
Model B
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New FEM model for thermal analysis of MV fuses
Results
Model A
Model B
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New FEM model for thermal analysis of MV fuses
Results
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New FEM model for thermal analysis of MV fuses
Complete fuse model
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New FEM model for thermal analysis of MV fuses
Meshing
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New FEM model for thermal analysis of MV fuses
Results
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New FEM model for thermal analysis of MV fuses
Results
RR20R20?(Tfus-20)
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Conclusions

• Simulation techniques can reduce the need for
  testing
• The FEM is proposed to obtain the thermal
  behaviour of MV current limiting fuses
• Commercial FEM package COSMOS Design Star
• Comparison with test results verifies the
  validity of the approach