Do you have a schematic of a delta corner grounded

Ok, I get the mid point tapped neutral Δ but the corner grounded Δis hard to understand attaching a corner of phase or a line? to ground.

I can't see how using my picture you can intentionally ground any secondary phase line or corner???

Can someone point me to a schematic similar to this one that shows how the corner is connected to ground.

I picture a single phase transformer as an electrically/magnetically powered stationary generator. Not sure I have it 100% but think I understand how you can attach a 1 phase control transformer to 3phase Y power to make 1 phase control power. Then ground at secondary side if phased appropiately ie attach L1 primary to H1 and L2 or L3 to H2 and then X2 becomes the return and can be grounded for secondary (and use primary neutral and or ground but this does not totally isolate the circuits).
Or I think you can use X1 as a grounded return if it will be a truely seperately derived system and will not share Neutral/Ground connection with primary side but there will be a inverse in wave form phase from primary to secondary.

So having typed that..... So do you just do it similarly and maybe like this

Y-Δ(corner grounded)
Transformer1
A-H1, B-H2 then X2-ground X1 - becomes a phase seconday
Transformer 2
B-H1, C-H2 then X2 ground X1 becomes b phase seconday
Transformer 3
C-H1, A-H2 then X1 to ground and X2 becomes c phase seconday

And or how would you configure a Δ-Δ corner grounded bank?

As far as I can see on your attached schematic, none of the secondary delta "corners" is connected to ground. Only the center point of the A phase secondary is tied to a ground / neutral line. The delta corners or connection points are all tied to the secondary a,b,c lines.

The A phase secondary center tap is simply providing a 120V phase to neutral supply (for standard domestic single phase loads) which can be tapped off either the a or c lines - but not the b line.

Yes, that is my understanding too. My attached schematic is a center tapped phase (this creates a neutral point in secondary side of bank that can be tied to ground).

But how is the corner grounded of a Δ. Its hard to visualize attaching 1 of 3 energized lines to ground. But I think I am getting closer to understanding....


What I tried to think about with this in my original post
---------------------------------------------------
Transformer1
A-H1, B-H2 then X2-ground X1 - becomes a phase seconday
Transformer 2
B-H1, C-H2 then X2 ground X1 becomes b phase seconday
Transformer 3
C-H1, A-H2 then X1 to ground and X2 becomes c phase seconday
----------------------------------------------------------------

It hit me when my head hit the pillow that would almost be a Y secondary with X2 being the center tap grounded neutral if I had not mixed up tranformer 3's phasing. If I would correct No. 3 than attach all X2's together its a Y.

Let me try and draw something then attach it for thoughts. I think it just hit me right that the Y or Δ should only be thought of as beginning or end of the 3 power lines and anywhere inbetween they are like 3 seperate individual hot legs (if everything is working properly). So that for a delta I could end connect the transformer indivdual coils and if all are connected and can carry current then any of the 3 corners can be neutral and be connected to ground I think (B phase being grounded as convention). But there is probably a reason and order of phasing that I should learn.

Could you be thinking of the two transformer open delta connection?

In principle one could configure (in your schematic) the delta corner opposite the center-tapped side, as a neutral / earth. You still end up with an unsymmetrical outcome - not a balanced 3-phase set.

quite a few references with google
http://www.electrical-contractor.ne...cs/177456/New_3_Ph_3_Wire_Corner_Grounde.html

OK - Interesting.

This pdf is also worth a read which gives some background as to why this was (is?) used.

http://ecatalog.squared.com/techlib/docdetail.cfm?oid=09008926800b38e9