Sounds very much to be Shield Leads.

All White Insulation, possibly Tinned stranded conductors?
Should have some tagging either imprinted to the Insulation, or as a label tag - but not always.

Transformer's nameplate may indicate these shield leads on the schematic. The shield would be a dotted line between the coil and the core, and the lead would tap off one side (typically the right side), and run out to a termiantion number.

Not sure why they are not terminated - maybe because there are a couple methods of termination, or possibly some liability issues (???).

Here are some images of Transformer Core/Coil assemblies with Shields:

[Linked Image]

Image #1: 3 Phase 4 Wire Transformer with Shield Leads.
**Note the small white conductors running from each winding at the top (between the coil and the core).
They all collect around the middle, and run upwards on the core.
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[Linked Image]

Image #2: Core-Coil view of Spec. Transformer with Shielded Windings.
It's kind of hard to see, but there are small shield leads running out of each winding area.
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[Linked Image]

Image #3: Shield Leads Terminations Diagram.
This is from the Transformer above (Image #2), and describes the terminations of shield leads.
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[Linked Image]

Image #4: Coil and Shield Leads Schematic.
This is also from the Transformer above (Image #2).
Note the Core is bonded to Ground, and for each winding section, there is Tap info, Lead info, and Shield info.
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[Linked Image]

Image #5: Core/Coil view of another Spec. Transformer.
*** Note the Terminal Blocks where the shield leads terminate.

Contact General Electric, and ask them about the terminations of the shield leads, and what to bond them to.
They might refer you to an on-line document, or answer your question directly - or a little of both!
If they reference an on-line document, let us know where the document is at (paste the link in your reply).

Nevertheless, let us know what the outcome is!

Good luck!

Scott35

Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!