Pick the right transformer rating
From your connected load, demand factor and growth, we calculate the kVA needed, suggest a standard rating and show the full-load currents on both sides.
- Standard kVA rating
- LV and HV full-load currents
- Indicative fault level
Your inputs
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Demand vs rating
Indicative estimate only. Real results depend on your equipment, site conditions and applicable standards. This is not a design or an offer.
Want this checked by an engineer?
Send us your result and we’ll review it and prepare a recommendation and quotation.
Chat on WhatsApp insteadMethod & assumptions
- kVA neededkW × demand factor ÷ PF × (1 + growth) ÷ target loading.
- Standard ratings25, 63, 100, 160, 200, 250, 315, 400, 500, 630, 800, 1000, 1250, 1600, 2000, 2500 kVA.
- CurrentsI = kVA × 1000 ÷ (√3 × V).
- Fault levelFull-load current ÷ impedance - a rough upper bound at the transformer terminals.
- ImportantMotor starting, harmonics, ambient and the utility’s requirements can change the choice; we confirm in the proposal.
About this calculator
What demand factor should I use?
0.6 - 0.8 is typical for industrial plants where not everything runs at once. Use your actual load study if you have one.
Why a target loading of 80%?
It leaves headroom for peaks and keeps efficiency and life healthy. Utilities sometimes require different limits.
Oil-immersed or dry type?
Dry-type and cast-resin suit indoor, fire-sensitive areas; oil-immersed is typical outdoors. See our transformer range.
Do you supply and install?
We supply a full range and can support installation; send an enquiry.