What does LV-side, Phase 2 internally grounded" mean?

[andrewward]

Hi all,

I am using digsilent and it provides a check box titled "LV-side, phase 2 internally grounded" when I create a single phase Y-D two winding transformer.

What does it mean to have a delta winding that is "phase 2 internally grounded"?

thanks heaps.

 

[dpc]

How can you have a single-phase Y-D transformer?

 

[andrewward]

I know it sounds strange. But, digsilent allows me to do it! I wasn't trying to create a Y-D single phase transformer. But, I clicked those options by mistake and then that check box suddenly appeared. So I thought I'd ask to find out if anyone knows what it is for.

Could it be an option when three single phase banks are used to create a three phase transformer bank?

 

[busbar]

 
In North American parlance, it sounds similar to a “corner-grounded delta” system, where it is not possible to disconnect the grounding jumper from winding to transformer frame.

 

[andrewward]

So does that mean a corner-grounded delta system is three single phase transformers connected so that one winding (e.g. LV winding) is delta connected? But, where each single phase unit has a permanent grounding jumper between the LV winding and the frame?

 

[dpc]

Yes if it was three-phase xfmr, it would make sense, per busbar's example of corner-ground. I've never seen one internally grounded, but I guess it's possible.

480V wye-connected secondaries in three-phase units often have the neutral internally grounded.