Choosing a transformer means answering about ten questions in the right order. Here is the full path to frame your project, with the detail behind each step.
The starting point and the first price driver. Work it out from the current or the active power, add a margin (around +25 %), and take the next standard rating up. The full walkthrough, with calculators, is in the sizing guide.
The insulation technology: oil-immersed (liquid) for outdoor sites, higher ratings and the best cost; cast resin dry-type for indoor installation and fire safety.
Mineral oil (economical, outdoor) or ester fluid (high fire point, biodegradable, indoor or sensitive areas). We configure either, depending on your site.
Primary voltage on the MV side (15 or 20 kV are common in France), LV secondary (400 / 230 V), all at 50 Hz, not 60 Hz. This is where a unit is either built for the European grid or it is not; the IEC 60076 framework governs the design.
Dyn11 suits standard distribution (LV neutral available). Other groups answer specific needs such as parallel operation or unbalanced loads; we align it with your single-line diagram.
ONAN (natural, silent) or ONAF (fan-assisted, peak reserve). The mode follows the load profile and the environment; fans can also unlock a second-phase rating later.
DETC (off-circuit taps, stable network voltage) or OLTC (on-load, no interruption), depending on how much the supply voltage moves and how much continuity you need.
Plenty of IT, UPS or variable-speed drives? Plan for harmonics with a K-factor or a controlled derating; see K-factor & harmonics, decisive for data centers.
Ingress protection (IP), environmental classes for dry-type (E2 / C2 / F1), and protections such as a DGPT2 relay or a Buchholz relay on oil-immersed units, according to the installation and how the site operates.
Non-negotiable in Europe: CE marking, Ecodesign Tier 2, IEC / EN 60076 and WEEE. As the brand placing the unit on the market, that responsibility is ours; the full picture is on EU compliance.
Need the MV switchgear and the LV board as well? A prefabricated MV substation integrates the whole chain, turnkey.
No problem: enter what you know, leave the defaults elsewhere, or simply send your specification document. We frame the missing points with you, then come back with a firm quotation.
General decision-support method; the final choice depends on your installation and is validated against your specification.
With the power rating in kVA: it is the starting point and the first price driver. Then come the technology (oil-immersed or dry-type), the voltages, the vector group and the options. Our configurator follows exactly that order.
Non-linear loads (K-factor) and the power margin. Underestimating harmonics, or sizing too tight, produces a transformer that runs hot and ages fast.
That choice follows mostly from the environment: indoor installation and fire safety point to dry-type; outdoor, high power and cost point to oil-immersed. The target power rating helps settle it too.
Yes. Send your specification, or simply describe the project; we frame every parameter with you and come back with a compliant, firmly priced proposal.