Experimental Study on the Behavior of Aluminum Fuse Element Inside 24 kV, 50 kA High-Voltage Fuses

Round 1

Reviewer 1 Report

The authors presented an experimental study on the behavior of aluminum fuse element inside 24 kV, 50 kA high-voltage fuses.

 The contributions are sufficient for the manuscript to be published in Energies, however, some comments are offered for improving this article.

 The manuscript’s strengths.

 1) The objective of the study is clear and matches the scope of the journal.

2) The manuscript is well organized and easy to read.

3) The authors have compared the current study with the available literatura.

4) An interesting aspect of this manuscript is the tests carried out.

  The manuscript’s weaknesses.

1) The addition of a photograph of the equipment would be welcome.

2) The addition of more information on the equipment used would be welcome.

Author Response

Dear reviewer, thanks for your recommendations

We have made the requested changes.

1) We have included some images from the experime ts presented in figure from pdf file.

2) Main characteristics of the equipment used in the circuit are the follows:

• Three short-circuit generators, each with 2500MVA 120kA for 0.5s, with parallel operation possibilities;
• Six single-phase units of master brakers (12kV, 120kA);
• Three single-phase units of master makers (24kV, 330kA);
• Six single-phase units of master makers (12kV, 330kA);
• Nine single-phase step-up transformers (80MVA; 12/12/25/51kV)
• Four single-phase step-down transformers (10MVA; 10/0.125/0.25/0.5 kV);
• Capacitors bank for direct testing: trifazat 36 kV, 400 A
• Multichannel sequential programmer BE3200-type;
• Data acquisition system for measurement and processing with optical isolation (25 MS/s, input range 20mVDC÷100VDC).

Author Response File: Author Response.pdf

Reviewer 2 Report

The results of the study offered in the under-consideration paper may be interesting to some engineers, but in my opinion, the presented subject would be best suited for presentation at a technical conference. The level of innovation is, in my opinion, between low and medium for the Energies journal. Please outline how new the study is that is provided in the paper.

To demonstrate the current literature evaluation of the research challenge, please describe three to four papers from the years 2021 to 2022.

Section 2 shows details about the linear circuit test that is shown in Figure 1. This circuit is similar to the one presented in the reference paper 5. The authors must detail the results obtained in paper [5] and show what they have achieved in addition to what is presented in paper 5. In fact, this work is mentioned but in section 1, but I believe that section 2 should be completed with these details

In the section 2 there are no bibliographic references although I think it should be because there are some statements such as "The testing of fuses is carried out in accordance with international standards" that would require such references.

The formulas presented should be referenced if they are not demonstrated.

 Additionally, it would be helpful to include nomenclature for the symbols and abbreviations used.

Author Response

Dear reviewer, thanks for your recommendations.

Among the few works that fall under the theme addressed in our article, we can give an example [1].

1. Pleșca, A. Temperature distribution of HBC fuses with asymmetric electric current ratios through fuselinks. MDPI Energies 2018, 11, 1990; doi:10.3390/en11081990.

We can state after the analysis of this article published in MDPI Energies, that the main stages of the study of the phenomenology related to a HV fuse (in the case of the article from [1] the HBC based on the asymmetric distribution of the fuselink currents are studied) are the following: theoretical presentation of the phenomenology, modeling and numerical simulations, and finally experiments and the comparative study of the results. Also, in the case of the article proposed by the authors, we can say that the same basic stages are followed, the difference being that in this article we propose to study the breaking capacity of high currents of HV fuses. Also, we can specify that according to our knowledge, it is one of the few works (possibly the only one after the ones from the 70s) in which the study of HV fuses is carried out using fuse elements made exclusively of aluminum.

This article is a continuation of the one presented in [5], in which the problem regarding the breaking capacity of the minimum current I3 was addressed, while in the current article the study is extended to all series of currents related to the various types of severity encountered in operation.

We have added the main standards that regulate the study of HV fuses:

2. IEC 60038 – IEC standard voltages; International Electrotechnical Commission: Geneva, Switzerland, 2009;
3. IEC 60071-1 – Insulation coordination – Part 1: Definitions, principles and rules; International Electrotechnical Commission: Geneva, Switzerland, 2019;
4. IEC 60076-1 – Power transformers – Part 1: General; International Electrotechnical Commission: Geneva, Switzerland, 2011;
5. IEC 60076-7 – Power transformers – Part 7: Loading guide for mineral-oil-immersed power transformers; International Electrotechnical Commission: Geneva, Switzerland, 2018;
6. IEC 60076-12 – Power transformers – Part 12: Loading guide for dry-type power transformers; International Electrotechnical Commission: Geneva, Switzerland, 2008;
7. IEC 60282-1 – High-voltage fuses – Part 1: Current-limiting fuses; International Electrotechnical Commission: Geneva, Switzerland, 2020;
8. IEC 60282-1, High-voltage fuses – Part 1: Current-limiting fuses. IEC 60282-2, High-voltage fuses – Part 2: Expulsion fuses; International Electrotechnical Commission: Geneva, Switzerland, 2009;
9. IEC 60549 – High-voltage fuses for the external protection of shunt capacitors; International Electrotechnical Commission: Geneva, Switzerland, 2013;
10. IEC 60644 – Specification for high-voltage fuse-links for motor circuit applications; International Electrotechnical Commission: Geneva, Switzerland, 2019;
11. IEC TR 60890 – A method of temperature-rise assessment by extrapolation for partially type-tested assemblies (PTTA) of low-voltage switchgear and controlgear; International Electrotechnical Commission: Geneva, Switzerland, 2002.

Also, we have added references for the presented formulas.

Additionally, we have included a nomenclature for the symbols and abbreviations used.

I           current that flows throught the fuselink;

U_s        supply source voltage;

U_ap             test voltage;

I_1,2        prospective current (r.m.s.value of the a.c. component) in test duties 1 and 2;

I_C                   cut-off current;

r          making angle of short-circuit current;

j          initiation of arcing after voltage zero;

U_r        recovery voltage;

U_c        overvoltage;

T_pa       prearcing time;

T_arc       arcing time;

I₃          breaking current in test duty 3;

I₂t        Joule integral – total energy;

P_0x       additional power losses due to notches;

x₀         distance between notches;

s           total section of notches;

l₀          length of notches;

S          section of the fusible element;

l_p          perimeter of the fusible element section;

j           current density;

ρ          electrical resistivity;

ρ₀         initial electrical resistivity;

λ          thermal conductivity;

k          heat transfer coefficient;

θ          temperature;

θ_a         ambient temperature;

α_R        coefficient of variation of electrical resistivity with temperature;

α          asymmetric coefficient;

γ          density;

c          specific heat.

Author Response File: Author Response.pdf