Generator CT Iron Core Grounding

[bdf5526]

Hello,
We have current transformer at neutral point of the generator.

Strangely there is a metal braid connection from the body (cast resin) to neutral point phase conductor of the generator. (I assume its for the CT iron core)

We have this metal braid from all CTs to its respective phase conductor at neutral point.

If anyone experience this before please let me know.

 

[bdf5526]

Hi, this is the reply from the supplier:-

translated from Chinese (Mandarin ) to English. The terms not very correct I guess since I cant read Chinese Mandrarin.

"The CT connection shows on the pictures is not for neutral point connection or for CT coil grounding . It is for equal potential connection between the CT and busbar connection .

As you know , for the ring type current transformer , the primary winding will be the bus bar conductor, the primary and secondary insulated by the resin and the air. If the conductor in the high voltage , the potential discharge or the electric radiator will be happened between the busbar conductor and CT.
Even though the NPC is the neutral point connection , theoretically, the busbar conductor will be 0 potential , but consider of the system is 100% stator protection , so if the generator line side fault , the neutral point voltage will be rise to Up/ ， the potential discharge or the electric radiator maybe happened with this voltage if without the equal potential connection."


But if the distance of the CT is far enough, i do not understand why this equal potential connection need.

Just to share.