What does the manufacturer explain?
Schneider Electric's vector-group FAQ, last modified 17 May 2026, describes winding configurations and the phase-angle difference between them. Its example uses Yd11 for a particular wye/delta arrangement and phase relationship. That designation is not a voltage-ratio entry.
Critical Power Drafting is independent and is not affiliated with Schneider Electric. Preserve the manufacturer's exact capitalization and winding references rather than reconstruct a label from memory. This guide does not approve a connection, determine phase sequence or authorize parallel operation.
Which schedule entries answer different questions?
A single generic transformer type field cannot replace a controlled set of electrical inputs.
| Field | Retain from approved source | Question |
|---|---|---|
| Equipment | Tag and selected model | Which transformer? |
| Winding voltage | Separate winding ratings and units | Which voltage basis? |
| Vector group | Complete exact designation | Which configuration and phase relation? |
| Connection | Approved winding diagram | Which terminals and references? |
| Tap basis | Applicable approved setting record | Which rated arrangement? |
| Review | Responsible engineering reference | What is approved? |
How can a schedule look complete while missing a rating?
Illustrative example. A fictional submittal transfer sheet contains a vector-group label but leaves both winding voltage fields blank. The drawing register marks transformer data complete because the type column is populated.
The reviewer records the two missing ratings and requests the approved manufacturer data. The group label is retained unchanged. No voltage, tap setting or capacity is inferred from its letters or clock number, and the blank fields are not filled from another project.
What is the final drafting cross-check?
Reconcile the exact transformer identity, winding labels and ratings across the SLD, schedule and vendor connection drawing. Keep any unresolved discrepancy as an engineering input rather than an editorial correction.
Matching vector-group labels alone do not establish that two transformers are suitable for parallel operation. Engineering sign-off is performed only by the registered engineer on the job.
Common questions
What else should the bid team know?
Is the group clock number a voltage ratio?
No. Obtain the actual approved winding ratings.
Can a similar transformer fill missing schedule values?
No. Use the selected equipment and approved revision.
Does this checklist approve parallel operation?
No. That requires the responsible engineering assessment.