Progress on Second-Generation High-Temperature Superconductor Tape Targeting Resistive Fault Current Limiter Application
Round 1
Reviewer 1 Report
In this manuscript the authors present an extensive analysis about the tolerance to short-circuit current of II gen. HTS cable for potential use in fault-current limiters.
In my opinion. the paper is well-written, easy to follow, and the results presented are interesting for the community. Thus, I found it deserves publication, even if I have a concern about the compliance of the topic which I found more appropriate for other journals such as Materials.
I just note the manuscript can be improved with some minor revisions.
In particular, in the final paragraph of the introduction the authors cite a number of previous works on related topics. It would be useful to the reader if they enlighten their contribution here.
In figure 1 the authors show “the basic structure of a HTS tape used in fault current limiter”. They should clarify if this is the actual structure of the samples they analysed or just a general scheme.
It is not clear why the critical current of sample 1. Is it due to a critical temperature lower than 77 K or sample 1 is a dummy sample? The author should clarify this. In addition, they could add the critical temperature values of the analysed samples.
The labels in Figure 2b are barely readable, as well as different labels and legends in the other figures. The author should consider increasing the font size of the text in the figures or to increase the size of figures. Also, some figures are badly printed in B/N. Maybe a different color palette can be used.
At row 205 the authors state: “In order to display easily, the 205 voltage has been converted to volt per meter.” That is, they are displaying the electrical field. The authors should consider using more appropriate labels in the figures and text, then.
In figure 7 the authors show the surface condition of sample 4 after different impact tests. It could be useful to show also the sample before the tests.
At row 273 it is stated “the peak values of the overcurrent current Imax during HTS tape impact are about the same, and the anti-impact energy Qmax of all samples are also roughly identical. This shows that the impact tolerance to overcurrent is largely dependent on the structure of the HTS tapes and has little to do with the critical current of the tape itself.” This is true since the differences are within few %. Anyway, the choice of the y-scale range if figure 10 is too forced and a more appropriate range should be selected to show these minimal variations.
The sentence starting at row 351 is identically reported also in conclusions. This redundance should be solved.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Performance analysis of HTS tapes in order to improve their properties for use in resistive current limiter is an actual topic, investigated currently by several workgroups. As the HTS tapes are complex structures with many variable parameters, many thorough measurements are necessary to bring insight into the optimization of tape performance, which authors succeeded to perform.
General concept comments:
(1) While authors seem to be familiar with the relevant literature review (section "Introduction"), I found very unusual that the last citation in the whole article is already on the page 2 (line 69) of total 17 pages, meaning that no comparison at all was provided between the results from the cited literature and authors' results (or it was just not cited?)
(2) The discussion of the results should reveal (a) new correlations between the material design of the tapes and their properties, (b) relations between different sets of measurements, (c) comparison of results with literature (as mentioned above) and (d) proposals how to improve the design of the used HTS tapes, based on the results. However, vast majority of the text is a mere description of the graphs. The scientific value of the measured data could be significantly increased by an appropriate discussion. Unfortunately, also the "Conclusion" section is only a brief summary of the pure data.
I consider both of the above points a reason for a major revision.
Specific comments:
All specific comments are suggested only as minor improvements.
Line 56: please explain the abbreviation "NZPV"
Lines 245 and 256: Tape heated by impact is actually in direct contact with a thin gaseous layer nitrogen, with much lower heat conductance (compared to the one of liquid nitrogen); is that effect of any importance to your study?
Line 310: "the change of voltage is continuously conductive" Can authors clarify this statement?
Eq2: I recommend to use index "SC" instead of "Sc", as the Sc abbreviation (used along with other abbreviations for chemical elements) could be mistakenly understood as scandium
Eq2: Indices of R's are not explained until the lines 118-120 (and just implicitly) - add explanation for the indices to Tab1?
Fig1a: please use different colour scheme for the Hastelloy (and add its text label), it is almost undistinguishable from the bottom Ag layer
Fig3a: Except for the red line, I could not distinguish any other lines (similarly for Fig4b)
Fig7: Asignment of letters (a), (b) and (c) is a bit confusing in the present layout, I'd recommend to move the letters to the right-hand side; similar with Fig13
Fig8: Would it be possible to select fewer lines to improve readability?
Fig13a, Fig13b, Fig13c, and Fig13d: At which temperature were they measured?
Fig13d: Please mention explicitly the meaning of the red circle.
Fig13e: the red dotted line is almost invisible.
Tab2: Lamination thickness: use brackets (80+80)um or move the units to the column caption
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Thanks to the authors for thorough addressing all my comments point-by-point. I consider all my comments were answered very reasonably, or at least satisfactorily. Just one minor formal advice: embedding the (a) (b) (c) ... labels into figures themselves (instead in typing them in form of a text) could probably prevent the letters to float away from the subfigures.
