Transformer sizing records
How to keep transformer load, current, kVA, impedance and review assumptions organised for Australian electrical project worksheets.
Record purpose
Transformer sizing work usually combines load records, current relationships, fault-current assumptions, utility requirements and product data. A worksheet should keep those pieces visible instead of hiding them behind one number.
AUWiring calculators help prepare relationship values. They do not replace transformer selection, installation design or utility approval.
Workflow
- Build the load basis from maximum demand, schedule or project information.
- Convert relevant kVA, current and voltage relationships with the transformer calculator.
- Record transformer impedance where fault-current review is needed.
- Separate normal-load review from fault-current review.
- Keep utility, manufacturer and engineering review notes attached to the worksheet.
Sizing record
| Field | Record | Why it matters |
|---|---|---|
| Load basis | Maximum demand, load schedule or project assumption | Sets the planning context |
| kVA basis | Existing transformer, proposed transformer or calculated relationship | Clarifies what is being checked |
| Voltage ratings | Primary and secondary values | Prevents side-mixing errors |
| Current values | Primary and secondary current records | Supports cable and switchboard review |
| Percent impedance | Transformer data where fault review is needed | Supports prospective-current worksheet |
| Review source | Utility, manufacturer or engineering source | Controls final decisions |
Boundaries
- Do not present a worksheet kVA as final transformer selection.
- Do not combine normal-load and fault-current results without labels.
- Do not hide voltage side, impedance source or load basis.
- Do not skip utility and project review where supply conditions control the result.