Transformer Parallel Operation Capacity Planner
Estimate the combined available capacity of two transformers and show their approximate loading when they share a common demand. The sharing proportions are user-entered rather than assumed from transformer theory.
Model parallel transformer loading
Parallel operation result
| Transformer | Usable capacity | Load share | Current load | Current utilization |
|---|
How the capacity model works
Each transformer rating is multiplied by its user-entered usable-capacity factor. The two usable capacities are then added to produce a combined planning capacity.
Usable capacity = Rated capacity × Usable-capacity factor
The user-entered load-share percentage determines how the present common demand is allocated between the two transformers.
Transformer 1 load = Shared demand × Load-share percentage
Why load sharing is explicit
Actual transformer load sharing depends on equipment characteristics and system conditions. This calculator does not invent a sharing rule. It allows the project team to enter the expected or measured sharing assumption.
Reserve planning
The reserve percentage is used to show the portion of usable combined capacity that you would prefer to keep uncommitted. It is a planning preference, not an engineering limit.
Important limitations
- The tool does not verify compatibility for parallel operation.
- It does not calculate circulating current or impedance mismatch.
- It does not determine protection settings.
- It does not replace manufacturer or engineering review.
FAQs
Can transformer sizes be different?
Yes. Enter different ratings and a sharing assumption appropriate to your installation.
Can one transformer have reduced usable capacity?
Yes. The capacity factor can represent a user-defined planning derating.
Why is future demand included?
It provides a quick check of whether today's combined capacity remains sufficient after a planned load addition.
Does this prove transformers can run in parallel?
No. Parallel operation requires technical compatibility checks beyond capacity arithmetic.