In this paper, the influence of electrostatic effect on the main shaft bearing current of wind turbine is studied, and a laboratory device with charge generator and small wind turbine is established. The experimental results show that electrostatic discharge effect is a mode of bearing current of wind turbine, which is more harmful to bearings. The author needs to improve the article in the following aspects:    

1 “Bearing current” is mentioned in the chapter title of Chapter 4, but the main body of this chapter only introduces the bearing impedance model, and does not introduce the bearing current. Please make amendments to this problem.

2 The titles of sections 5.2 and 5.3 are the same, please explain or modify them.

3 In Figure 17, why is the measured bearing voltage waveform not a square wave? In addition, please explain the voltage difference between bearing voltage and shaft voltage.

4 In Figure 21, why didn't the bearing voltage drop directly to 0V as in Figure. 22, when discharge breakdown occurred?

5 What is the purpose of PD discharge detection? Will the increased capacitance of PD detection unit affect the detection of bearing voltage and current?

The paper deals with an interesting topic - electrostatic discharge through bearings in wind turbines. Please consider the following comments:

- Please make it clearer when it comes to differences between the test setup and real wind turbine case. In a wind tubine (Fig. 4), an important point is the path of the discharge, either through the brushes or through the bearings. While in the test setup (Fig. 14), it seems that the only path is through the bearing. Is this correct? If yes, this must be highlighted more in the paper and conclusions. 

- Please elaborate more on this sentence (page 17 - 312): "Compared with the AC voltagedriven bearing current, the ESD-driven bearing current appears at a lower trigger voltage and higher current amplitude". Please explain how this could be a conclusion of this paper.