DELTA / DELTA transformer

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Flex said:
I know that's what's I'm saying
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Thanks for posting a picture of the schematic. You post seemed as if you had an X0 connection and when you stated that you had a D-D it didn't make any sense at all.
What was the purpose of the OP which asked "Why would a delta to delta transformer have an X0 terminal on the secondary side?"
Why is the question being asked? Help us out here a bit.
Do you need an X0? Why?
 
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Flex said:
I know that's what's I'm saying
Click to expand...

OK, let's see if this works:
1. The transformer is delta-delta.
2. There is a standard secondary terminal assembly which has four insulated mounting points, marked X0 through X3.
3. The secondary coil ends are attached to X1 X2 and X3.
Nothing is attached to X0.

So far that matches what the OP described and what the nameplate shows.

The alternatives:
A. The X0 terminal is connected to something but it is just an electromagnetic shield between the windings.
B. There is something connected to X0 and it has DC continuity to the other 3 X points. The transformer is really delta-wye and they put the wrong nameplate on it.
 
GoldDigger said:
OK, let's see if this works:
1. The transformer is delta-delta.
2. There is a standard secondary terminal assembly which has four insulated mounting points, marked X0 through X3.
3. The secondary coil ends are attached to X1 X2 and X3.
Nothing is attached to X0.

So far that matches what the OP described and what the nameplate shows.

The alternatives:
A. The X0 terminal is connected to something but it is just an electromagnetic shield between the windings.
B. There is something connected to X0 and it has DC continuity to the other 3 X points. The transformer is really delta-wye and they put the wrong nameplate on it.
Click to expand...

I'm thinking B.
 
The catalog number on the nameplate is for a non-shielded transformer with a 480V delta primary and a 240V delta secondary, which matches the wiring diagram. The standard design would not have a 4th "X" terminal of any type, however there would likely still be the factory jumper between the core assembly and the transformer enclosure.
 
The X0 bus seems to be simply acting as a connection point for grounding frame and core. If there were an actual neutral terminal from the secondary windings it would have been connected to that bus in a separately derived system configuration. Or if the apparent connections to it are really ends of secondary windings, it is actually a wye being used as a delta output!

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kwired said:
Where is this bottom bus? All I see is what looks like the lower portion of the core.
Click to expand...
I cannot tell whether the long metal strip with the three-hole patterns in it is really part of the core or is just a metal strap with some large diameter wires welded to it.
I suppose it might also connect to an inter-winding shield?
 
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