Brushes for hidrogenerators.

[nelvex]

I have several questions about the brushes that are used in hydrogenerators. I'm not referring here to those for static excitation but those that are used for protection and measurement. How many brushes of this type are used? It is a brush that makes contact with the machine shaft, is mounted isolated and used for detecting the first rotor earth fault. It also used another brush that makes contact with the shaft and is connected to ground for protection against electrostatic charging of the machine? Also brushes are also used for measuring current and voltage in the shaft? How many brushes which use usually. I would like more information regarding this.