Project snapshot
| Sector | Healthcare — city hospital, critical care |
| Region | Europe |
| Application | Distribution room located directly below occupied wards |
| Product | SCB13 cast resin dry-type transformer |
| Rating | [2 × 1600 kVA] |
| Voltage ratio | [10 / 0.4 kV] |
| Vector group | [Dyn11] |
| Cooling | AN with forced-air (AF) headroom |
| Enclosure | IP23 |
| Standard | IEC 60076-11 (dry-type), routine tests per IEC 60076 |
| Delivered | [Q3 2025] |
The challenge
The hospital’s transformer room sits directly below occupied wards. That single fact drove every design decision on this project — audible noise and fire risk had to be brought down to levels acceptable for a building that never empties, and it had to happen inside a room that could not be enlarged.
Three constraints had to be satisfied at once. Acoustics: transformer hum transmitted through the slab into patient rooms above is the single most common complaint in hospital electrical design, and night-time limits in ward areas are far tighter than in plant rooms. Fire safety: an occupied healthcare building is the worst possible location for a flammable insulating liquid, and any oil-filled solution would have required bundled containment, fire-rated separation and additional escape provisions that the existing room could not accommodate. Footprint: the available floor area was fixed, so the units had to deliver the required capacity — plus headroom for future load growth — without expanding the room.
Above all, the load is critical care. The installation could not be treated as a standard commercial distribution job where a few hours of downtime is tolerable.
Our solution Cast resin construction — no flammable liquid
We supplied SCB13 cast resin dry-type transformers. The windings are vacuum-cast in epoxy resin, giving a self-extinguishing, non-hygroscopic insulation system with no oil to contain, monitor or replace. This removed the fire-load question from the design review entirely and let the room stay exactly as built. Cast resin construction is the default choice for occupied buildings for this reason — see our comparison of oil-immersed vs dry-type transformers.
Low-noise core and mechanical design
Acoustic performance was engineered, not filtered after the fact. The core is run at a reduced flux density with step-lap joint construction, and the complete assembly is mounted on anti-vibration pads with damped fixing to the enclosure frame. Sound pressure level was verified by measurement at [1 m, [XX] dB(A)] rather than quoted from a catalogue.
IP23 enclosure with forced-air (AF) cooling
The units are supplied in IP23 enclosures fitted with forced-air cooling. In practice this means the transformer carries its full rating on natural air cooling (AN) and can be pushed into its AF rating when the building load peaks — summer cooling demand, or future ward expansion — instead of being replaced. For a hospital with a fixed plant room, that headroom is usually worth more than the initial saving on a smaller unit. If you are specifying cooling classes, our guide to ONAN, ONAF, AN and AF explains what each rating actually permits.
Low-loss SCB13 for continuous running cost
Hospital distribution transformers run 24 hours a day, every day of the year, so no-load loss dominates lifetime cost. The SCB13 loss level was selected over the older SCB11 design specifically for that duty profile; where the load factor justifies it, an amorphous alloy (SCBH15) core cuts no-load loss further still.
Technical specification
| Rated power | [2 × 1600 kVA] |
| Primary / secondary | [10 / 0.4 kV] |
| Frequency | [50 Hz] |
| Vector group | [Dyn11] |
| Impedance voltage | [6 %] |
| Insulation class | F [temperature rise 100 K] |
| Cooling | AN / AF |
| Enclosure | IP23, [RAL …] |
| Sound level | [XX dB(A)] at 1 m |
| Standards | IEC 60076-11; routine tests per IEC 60076-1 |
Testing and verification
Every unit was routine-tested before shipment: winding resistance measurement, voltage ratio and vector group check, insulation resistance, separate-source AC withstand voltage, induced overvoltage withstand, and no-load loss and current measurement. Sound level was measured on the completed assembly, not calculated. [FAT witnessed by the client / third-party inspector — confirm]. The full test sequence and how to read a certificate are covered in Transformer Routine Testing: What Every Unit Should Pass.
Result
The hospital took delivery of quiet, fire-safe power for its critical care areas without any change to the plant room footprint, and without adding oil containment or fire-rated separation to the electrical design. The AF rating leaves headroom for future ward expansion rather than committing the hospital to a premature replacement.
Frequently asked questions
Why dry-type rather than oil-immersed in a hospital?
Cast resin contains no flammable liquid, so it does not need oil containment, fire-rated separation or leak monitoring. In an occupied building with patients who cannot be evacuated quickly, that removes the dominant fire risk from the electrical design. Dry-type is also the standard expectation in healthcare specifications.
How quiet is “low-noise”, and how is it measured?
Sound level is measured as a sound pressure level in dB(A) at a defined distance (typically 1 m) under defined load and cooling conditions. Catalogue figures are often quoted for the ideal case; we measure the completed unit in its enclosure. Always state the measurement distance and whether AF cooling is running, because forced-air fans add to the figure.
Does AF forced-air cooling change the transformer rating?
Yes — it raises the continuous rating above the natural-air (AN) figure, typically by around 40–50 % on cast resin designs, but only while the fans are running. It is useful as headroom for peak or future load, not as a basis for the normal duty rating.
Can the transformer be installed directly below wards?
Yes, provided three things are dealt with in the design: measured sound level against the ward limit, anti-vibration mounting to stop structure-borne transmission, and a dry-type (non-flammable) insulation system. This project addressed all three.
Planning a hospital or healthcare transformer room? See our commercial and institutional building solutions, or send us your single-line diagram — we return a technical proposal and indicative price within 24 hours.