A Fast Calculation of Partially Corroded, Grounding-Resistive Electrode Electrical Parameters

Round 1

Reviewer 1 Report

The paper presents modelling to calculate grounding resistance considering partially corroded electrodes. The document is well-written and provides an interesting topic for the scientific community. However, I do have some concerns that I would like to share.

1 - The authors could be a little bit more rigorous on details such as: spaces between numbers and their units (such as the data from page 3); the figure caption should be improved; 

2 - The authors should provide the source where he considered the oxide layer (and thickness);

3 - The authors should provide the software in which the simulation was done;

4 - I recommend avoiding the term "error" in Fig. 7. In my opinion, when one uses this term, it is considered a well-known benchmark (such as a measurement, for instance).

5 - The authors should provide references where they got the grounding data information, for instance, the Transmission Line grounding system.

6 - The "Vertical deep-well grounding electrode partially corroded" case should have more details. For instance, how was it considered the interface between the layers? Moreover, what are the validation limits for applying such a technique in this specific grounding system, i.e., is your model physically consistent for this case?

7 - I recommend the authors provide more details about oxidation. For instance, how long and in which situation does the grounding system present such a critical oxidation? Do the authors have any references concerning the oxidation data?

Finally, I would like to congratulate the authors since the paper is on such an interesting subject.

Author Response

Reply to reviewer1

Thank you very much for your comments and suggestions, which undoubtedly contribute to improving this paper. We proceed to discuss one by one the points that you mention in your evaluation of this work. Highlighted in yellow are the words, phrases and paragraphs added and/or retouched throughout the text, following the suggestions and recommendations of the referees of this paper.

1 - The authors could be a little bit more rigorous on details such as: spaces between numbers and their units (such as the data from page 3); the figure caption should be improved; 

We have reviewed all data and units adopting an appropriate presentation format. Some of the captions have also been retouched.

2 - The authors should provide the source where he considered the oxide layer (and thickness);

In each proposed example, a comment about the oxide layer or coating material has been added.

3 - The authors should provide the software in which the simulation was done;

We understand that you are referring to the computing platform used to encode the numerical algorithms that implement the model. This platform is MatLab, widely used in engineering applications. A short comment has been added at the end of section 2.

4 - I recommend avoiding the term "error" in Fig. 7. In my opinion, when one uses this term, it is considered a well-known benchmark (such as a measurement, for instance).

Done!.

5 - The authors should provide references where they got the grounding data information, for instance, the Transmission Line grounding system.

A short sentence about the sources of examples 2 and 3 has been added. On this issue, any reference to the grounding systems discussed in the paper points to technical documentation in Spanish of little interest for the objectives of this work.

6 - The "Vertical deep-well grounding electrode partially corroded" case should have more details. For instance, how was it considered the interface between the layers? Moreover, what are the validation limits for applying such a technique in this specific grounding system, i.e., is your model physically consistent for this case?

A few clarifying sentences have been added in this example. To the best of our knowledge, this type of grounding electrode is not found in the Spanish electrical system. However, there is a growing interest in knowing its characteristics and mode of operation. Reference [13] contains the necessary information to have a first contact with this type of electrodes. Our model allows us to analyze the behavior of these very long electrodes without presenting any problem, apart from requiring a little more computation time due to the high number of segments that must be processed.

7 - I recommend the authors provide more details about oxidation. For instance, how long and in which situation does the grounding system present such a critical oxidation? Do the authors have any references concerning the oxidation data?

The details about the oxidation process of the electrodes has not been an objective of this work. The main interest is to test a model that combines the internal resistance of the conductors with their surface oxidation in order to evaluate the impact on the most important parameters of a grounding electrode. To put it simply, our source is an electrode that is already partially oxidized without worrying about how that situation has been achieved. All the data we have on oxidation come from technical reports supplied by the aforementioned firm INGESCO, which allows us to use this information only for scientific purposes.

Author Response File: Author Response.docx

Reviewer 2 Report

This manuscript utilizes theoretical background previously published by the authors with minor addons concerning the corrosive coating (this is also unclear whether the authors have published already). The previously published model is inadequately summarized in this paper so one has to read the previous published papers to get an insight about the working of the model.

The authors mainly concern themselves with the usage of the said grounding system model with the possibility of adding corrosive or similar coating layer to certain grounding conductors. The analysis is performed poorly on four different examples with no regard to the effect of varying for example the resistivity of the corrosive layer, the thickness of the corrosive layer, or the total covering of the grounding system (partial or full cover). This could be a good paper, but in this form in my opinion is unpublishable.

Author Response

Reply to reviewer2

Thank you very much for your assessment of this paper on which we would like to make some comments. Although it is true that the two basic elements of the paper, internal resistance and surface corrosion, have been previously modeled separately by the authors, the combination of both in a single model represents a new model that is broader than the previous two. It is also true that the paper is not self-contained, nor does it pretend to be. Adding the details of the two models involved would make the paper too long. The references to the sources of the proposed model are complete enough not to include them here.

Regarding the comment about varying the resistivity and thickness of the oxide layer as a way to better analyze the impact of these added properties, it should be noted that the objective is actually to compare the electrical parameters of an ideal electrode, that is without internal resistance and clean of oxide, with those of an electrode affected by these added attributes. If the added features correspond to values close to real ones, as it is in some of the examples discussed, the comparison is useful to assess whether the electrical parameters may fall outside the regulatory safety standards.

Author Response File: Author Response.docx

Reviewer 3 Report

The significance of the paper for future reseach should be explained a bit more.

1. main question 

The authors applied they method for equivalenting coated conductor (ref. 6) for modeling corroded grounding electrode (treating it as coated electrode) and determining influence of corrosion on grounding characteristic.

2. topic original or relevant in the fields

I ti e extension of the application of the method recently proposed (ref. 6, so I believe it is relevant).

Also, although grounding systems are object of research for decades, new tools provide possibility for solving more realistic problems which were not possible to solve before.

3. new subject area compared with other published material

They probably did not have published results for comparison (they believe in tools and method, which is OK. Packages are accepted as accurate and method is based on previously published paper.). 

4. improvements regarding the methodology

Extension of the recently proposed method on corroded conductor is sufficient improvements.

The results are OK, but comparison with real ones is missing. Or with the results obtained using other packages and methods (if there is any).

references are appropriate.

Generally, it is hard to expect that authors will have measured values which can be compared with obtained results, since it is hard to realize such measure.

The type of influence of corrosion was expected. But about level is hard to say.

The researchers are experienced and I believe that paper is correct.

My remark was only directed on purpose and further use of obtained results.

Author Response

Response to reviewer 3

Dear reviewer,

thank you very much for your comments, which indicate that you have carefully read our work and have understood its scope. Following your suggestions, we have added some text in the introduction, the second paragraph, and a last paragraph in the conclusions to enhance the scope of the proposed methods. As a summary of these additions, we can say that the incorporation of coatings in the electrodes supposes a formidable complication in the calculation of the electrical parameters, unless some simple method allows the evaluation of its effects. This is precisely one of the key points of the paper. We must also indicate that it is difficult to obtain field information about oxidized electrodes since it implies a considerable effort. Our work can help to evaluate the degree of oxidation of an electrode based on measurements of the actual grounding resistance compared to the theoretical values.

We hope that the new paragraphs included meet your suggestions which, along with those of other reviewers, have contributed to improving the quality of this paper.

Round 2

Reviewer 1 Report

First I would like to thank the authors for taking into consideration all of my comments. Said that, I do not have any additional comments.

Author Response

Thank you very much for your evaluation of the paper. Without a doubt, your comments have contributed to improving the quality of this work.