Representation of Time-Current Characteristic of Expulsion Fuse Links for

Computer-aided Simulations

Code: 12.035

G. B. Costa, A. C. Marchesan, A. Z. Bertoletti, A. P. Morais, G.

Cardoso Jr e L. Zapata.

Universidade Federal de Santa Maria - UFSM

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Model the Time-Current Characteristics (TCC) of expulsion fuse links. To

achieve this, the Last Square Method has been used and the Residual

Sum of Squares (RSS) as a comparative parameter.

Four equations were selected to evaluate the method.

Objectives

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Expulsion fuse links are widely used in the protection of overhead

distribution systems, specifically in branches and equipment such as

transformers and capacitor banks due to their simplicity and low cost in

relation to other protection devices.

Due to the popularization of expulsion fuse links, a great number of studies

focus on the distribution protection schemes considering the presence of

these devices. When research involves computational simulations, it is

necessary to represent the fuse element using digital models. Generally,

the data used in these models are obtained through Time-Current Curves

(TCC).

From the data obtained from the TCC curves, there are several

approaches proposed in the literature for fuse links modeling. In this work,

the aim is to evaluate the methodologies that employ analytical equations

to represent the mathematical behavior of these devices in computational

simulations.

Introduction

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Methodology

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START

STEP 1

Obtaining the MM and TC curve from the

manufacturer

STEP 2

Collecting at least 60 points from the MM

and TC curves

STEP 3

Process the curve fitting of selected

function

END

STEP 4

Evaluate the goodness of function fit

Methodology

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Formula Equation

𝑡 = 𝑝0 + 𝑝1. 𝐼 + 𝑝2. 𝐼2 +⋯ (2)

𝑡 = 𝑎. 𝑒𝑥𝑝 𝑏. 𝐼 + 𝑐. 𝑒𝑥𝑝(𝑑. 𝐼) (3)

𝑡 =𝐴

𝐼𝑛 − 1+ 𝐵 (5)

𝑡 = 𝐴0 +𝐴1𝐼 − 1

+𝐴2

𝐼 − 1 2+⋯ (8)

BI

At

n

1

n

qI

Ib

IhI

KCt

50.

)( 2

)(log)log()log(

2

210

I

A

I

AAt

2

210

)1()1( I

A

I

AAt

Fuse Link type “H” x RSS of TC curve using Equation (5).

Experimental results

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1,47

3,54

1,20,76

5,24 5,03 5,13

2,71

3,56

7,34

9,5

10,58

1H 2H 3H 5H

0

2

4

6

8

10

12

R

SS

Elo Fusível tipo "H"

Delmar Hubbell Power Systems

Eletrofusi Power System

Indel Bauru

Fuse Link type “H” x RSS of MM curve using Double Exponential.

Experimental results

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0,580,71

0,79 0,86

0,57 0,6

0,94

0,15

1,66

2,87

3,5

3,91

1H 2H 3H 5H

0,0

0,5

1,0

1,5

2,0

2,5

3,0

3,5

4,0

R

SS

Elo Fusível tipo "H"

Delmar Hubbell Power Systems

Eletrofusi Power System

Indel Bauru

Fuse Link type “H” x RSS of TC curse using Polynomial Function.

Experimental results

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0,13

0,94

0,82 0,84

0,19

0,07

0,25

0,35

0,16

0,27

0,19

0,62

1H 2H 3H 5H

0,0

0,2

0,4

0,6

0,8

1,0

1,2

R

SS

Elo Fusível tipo "H"

Delmar Hubbell Power Systems

Eletrofusi Power System

Indel Bauru

Fuse Link type “K” x RSS of MM curse using Equation (5).

Experimental results

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4,34

4,98

3,964,15

3,08

3,41

2

3,25

4,74

3,7

4,3

3,39

1,77

2,6

3,56

1,55 1,46 1,441,62 1,64 1,62

6K 10K 15K 25K 40K 65K 100K

0

2

4

6

R

SS

Elo Fusível tipo "K"

S&C Positrol®

Eletrofusi Power System

Cooper Power Systems Kearney™

Fuse Link type “K” x RSS of TC curse using Equation (8).

Experimental results

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1,12

1,34

1,58

2,26

1,821,72

0,66

0,12

0,420,3

0,11 0,07

0,230,17

0,10,12 0,09

0,29

0,48

0,2

0,78

6K 10K 15K 25K 40K 65K 100K

0

1

2

3

R

SS

Elo Fusível tipo "K"

S&C Positrol®

Eletrofusi Power System

Cooper Power Systems Kearney™

Expulsion fuse links are widely used in the protection of overhead

distribution systems as a result of their simplicity and low cost in relation to

other devices.

Hence, this study evaluated four different analytical functions proposed in

the literature to model the MM and TC characteristics of expulsion fuse

links, using the adjustment of the Least Squares Method. Three major

manufacturers were considered. As a criterion for evaluating the quality of

the analyzed adjustments, the Residual Sum of Squares (RSS) was

adopted.

The Polynomial function presented the best results among the selected

functions. The average RSS values were the lowest considering the four

functions. The disadvantage of the method, according to the study criteria

selected by the authors, is that there is no single polynomial order that fits

for all the full range of fuse links nominal values.

Conclusions

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The authors are thankful to Brazilian government through Capes

(Coordenação de Aperfeiçoamento de Pessoal de Nível Superior). This

work was supported by Capes.

Acknowledgments

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