A New Effective Method of Induction Machine Condition Assessment Based on Zero-Sequence Voltage (ZSV) Symptoms
Round 1
Reviewer 1 Report
- The literature review in the introduction is very exhaustive.
- What is actually presented in the literature [1-3]?
- Row 250-251: what exactly can be found in references [59-61]?
- Row 512: According to which authors?
- Row 346: What does the bracket above the condition represent?
- Figure 11. x-axis label should be corrected.
- Row 537: The neutral point is never accesible on the machine's nameplate, it can be found in the machine's terminal box.
- Is there any difference between the proposed measurement circuit in Figure 2 and the measurement circuit proposed in references [13] and [18]?
Author Response
Response to Reviewer 1 Comments
Thank you for spending precious time on our previous manuscript and your valuable suggestions. The responses are detailed following each comment. Necessary explanations have been added to the revised paper. The changes have been highlighted in turquoise.
Point 1: The literature review in the introduction is very exhaustive.
- What is actually presented in the literature [1-3]?
- Row 250-251: what exactly can be found in references [59-61]?
- Row 512: According to which authors?
Response 1: Thanks for the comment. We provide information about the changes we made in particular points.
Ad.1.
Regarding this point, we changed the order of references positions [2] and [3] arranging the references [1-3] starting with the latest. When selecting the literature we considered these references to be survey papers containing the state of art on diagnostic methods for induction machines developed for years. In the paper, we changed the sentence referencing the literature to:
In many papers, the state-of-art on electric machine diagnostic methods is presented. In selected papers, one can find the state of art on diagnostic methods and their respective development directions [1-3].
Ad.2.
Thank you very much for the deep analysis of our references. In lines 250-251 we cited the references which only partially referred to the issues described in this part of the paper. These three references were rearranged and moved to new positions in the literature list. This allows for referencing in the text in the right order.
Work [59] was moved to position [61] and it refers modeling. Similarly, the papers [57] and [60] according to the new numeration which were referenced in this place.
Work [60] was moved to position [45] and it was cited as the reference concerning the application of zero sequence current component in the development of control algorithms and multilevel converters diagnostics.
Paper [61] was moved to position [48] and it refers to application of Multi-label classification in machine diagnostics in modern drive systems. All these changes caused the change in literaturę numeration from the position [45] to the end of the list.
Ad.3. The sentence concerns the authors of this article.
It was changed and highlighted in the text.
Point 2: Row 346: What does the bracket above the condition represent?
Response 2: Thanks for the comment. The bracket is unnecessary. It has been erased.
Point 3: Figure 11. x-axis label should be corrected.
Response 3: Thanks for the comment. The x-axis label has been corrected.
This figure after changes is now of the form:
Point 4: Row 537: The neutral point is never accessible on the machine's nameplate, it can be found in the machine's terminal box.
Response 4: Thanks for the comment. It is corrected. This error occurred during text translation and correction. For this reason, we missed it. Once again, thank you for your feedback.
Point 5: Is there any difference between the proposed measurement circuit in Figure 2 and the measurement circuit proposed in references [13] and [18]?
Response 5: Thanks for the comment. There is no difference between the measurement circuit shown in Figure 2 and those proposed in references [13] and [18]. The references [13] and [18] have been put in the Fig. 2 titles.
Author Response File: 
Author Response.docx
Reviewer 2 Report
FEM Analysis
The simulation model is not well described.
Geometrical data about the simulated model are missing, as airgap, dimension of the slots, etc…
Voltage source neutral connection
The supply voltage is connected to ground. Is it possible to perform the method with other neutral connection?
Is there any influence with the neutral resistance connection?
Experimental setup
Please could you include more detail about the induction motor under test. For example, number of slots, position of the two broken bars… are the two bars adjacent
How the eccentricities are produced in the motor? Could you include more detail about it?
Conclusions
Conclusions should be point 7 not 8
Author Response
Response to Reviewer 2 Comments
Thank you for spending precious time on our previous manuscript and your valuable suggestions. The responses are detailed following each comment. Necessary explanations have been added in the revised paper. The changes are highlighted in green.
Point 1: FEM Analysis
The simulation model is not well described. Geometrical data about the simulated model are missing, as airgap, dimension of the slots, etc…
Response 1: Thanks for the comment. Geometrical data has been complemented by: air gap length, machine core length, inside stator radius, outside stator radius and technical drawings of stator, rotor slots with dimensions (Fig. 9).
Now it is written in the paper as follows:
For simulation of a 2D model of the induction motor, the Maxwell 2D with Transient Solver add-on was used as a part of the Maxwell-ANSYS environment. The investigated machine was an Sg112m-4 motor whose parameters were as follows: PN = 4 kW, UN = 400 V, IN = 8.1 A, nN = 1430 rpm, p = 2, air gap length = 0.3 mm, machine axial length = 117 mm, inside stator radius = 59 mm, outside stator radius = 92.04 mm, number of stator slots Ns = 36, and rotor cage bars number N = 28. The geometry of the examined motor was modeled based on the schema of the machine’s winding, and technical drawings of the stator and rotor. M19 steel with a non-linear magnetizing curve was used in the model. Figure 9 shows the electric circuit model in the FEM software and the B-H curve.
Point 2: Voltage source neutral connection
The supply voltage is connected to the ground. Is it possible to perform the method with other neutral connection?
Response 2: Thanks for the comment. The presented method of induction motors diagnostic based on ZSV is also effective when analyzing neutral wire current in of machine with star winding configuration.
Neutral wire current
contains the same characteristic frequencies as zero-sequence voltage component. The frequency spectrum of zero sequence voltage component was compared with the frequency spectrum of neutral wire current of the motor with eccentricity (77%) obtained from FEM simulation. The investigated machine was Sg112M-4 motor, whose nominal parameters and dimensions are described in this paper. The following circuits presented in Fig. 1 were used for simulations
Figures below show static eccentricity characteristic frequencies obtained from the algorithm presented in this paper.
As shown in Fig. 2, the same fault related harmonics are present in zero sequence voltage component and neutral wire current frequency spectra. In this case, the fault is static eccentricity.
Is there any influence on the neutral resistance connection?
Such a case was not investigated, however, one can expect that the influence of ZSV measurement through a resistor would be visible in case of the asymmetric voltage supply. An important feature of the measurement system (Fig. 3a) is the use of balancing resistors R which separates ZSV from voltage supply amplitude asymmetry. In the case of ZSV measurement shown in Fig. 3b, it is not possible.
Initial investigation of zero sequence current component for the following winding configurations: star with neutral wire and delta, was performed. It will be considered in future works.
Point 3: Experimental setup
Please could you include more detail about the induction motor under test? For example, the number of slots, the position of the two broken bars… are the two bars adjacent
How the eccentricities are produced in the motor? Could you include more detail about it?
Response 3: Thanks for the comment. The mentioned details about the induction motor under test have added to the text.
The text in the previous version was changed from:
For measurements of the motor with rotor cage asymmetry a rotor with two broken bars was used, and for measurements of the machine’s eccentricity case, a rotor assembled on eccentrically mounted bearings was used, which allowed us to obtain a dynamic eccentricity level of and static eccentricity level of .
To the one that more accurately describes the modifications of the machine.
For measurements of the motor with rotor cage asymmetry a rotor with two adjacent broken bars was used, and for measurements of the machine’s eccentricity case, a rotor assembled on eccentrically mounted bearing shields and eccentrically mounted shaft of rotor was used. During mechanical machining of bearing shields, the symmetry axis was shifted by 0.12mm which allowed for obtaining static eccentricity level of . Also during mechanical machining of the rotor, while mounting the steel sheet on rotor shaft its symmetry axis was shifted by 0.12mm which allowed to obtain dynamic eccentricity level of .
Thanks to the modifications of bearing shields and the rotor of the machine of interest, a mixed eccentricity was obtained.
We hope that information added to the text is sufficient and well describes the process of machine’s modification which allowed to obtain mixed eccentricity.
Point 4: Conclusions
Conclusions should be point 7 not 8
Response 4: Thanks for the comment. The number of the chapter has been corrected.
Changes of chapters and subchapters for which the numeration was changed are highlighted.
Author Response File: Author Response.docx
Reviewer 3 Report
The authors had proposed a new method to assess the condition of Induction machine. The paper is well written and easy to assess the proposed method.
1. There are other techniques already proposed in the literature which authors had mentioned in the literature. In my opinion ,if the author can present numerical comparison of the proposed technique with already published technique, it will much strengthen the proposed idea.
2. Is the proposed method computationally efficient as compared to already proposed technique?
Author Response
Response to Reviewer 3 Comments
Thank you for spending precious time on our previous manuscript and your valuable suggestions. The responses are detailed following each comment. Necessary explanations have been added to the revised paper.
The authors had proposed a new method to assess the condition of the Induction machine. The paper is well written and easy to assess the proposed method.
Thank you very much for flattering feedback on our paper.
Point 1: There are other techniques already proposed in the literature which authors had mentioned in the literature. In my opinion, if the author can present a numerical comparison of the proposed technique with already published technique, it will much strengthen the proposed idea.
Response 1: Thanks for your precious suggestion makes. The paper does not present the invention of the computational cost of numerical accuracy of the method. It will be considered in future work. The scope of the research presented in this paper was to investigate the effectiveness of the method in the induction machine’s fault detection.
Point 2: Is the proposed method computationally efficient as compared to the already proposed technique?
Response 2: Thanks for the comment.
The algorithm of generation of reference frequencies has a low computational cost and is not more complex than the algorithm used for the MCSA method. The mathematical model of the machine is also quite simple in terms of computational cost.
At the end of section 4. Mathematical Model of the Cage Induction Motor we added a sentence regarding the computational complexity of the algorithm for the generation of characteristic frequencies and the mathematical model used.
These two sentences are highlighted in yellow in the corrected version of the article.
The algorithm of generation of reference frequencies has a low computational cost and is not more complex than the algorithm used for the MCSA method. The mathematical model of the machine is also quite simple in terms of computational cost.
We hope that this is sufficient. These two remarks above are very valuable to us. Once again, thank you very much for their formulation.
Author Response File: Author Response.docx
