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Dry-Type Transformers

Epoxy-resin cast SCB series transformers, 6.3–22 kV, class F/H, for indoor, building and industrial installations.

Cast-resin coils of a dry-type transformer in a test hall

Cast-resin dry-type transformers

Where oil is not permitted — inside buildings, hospitals, data centres, tunnels, offshore platforms and factories — a cast-resin dry-type transformer provides fire-safe, maintenance-free distribution. MARS SCB10/SCB13 series units cover 100 to 2,500 kVA at 6.3, 10, 11, 13.8, 15, 20 and 22 kV, with class F (155 °C) or class H (180 °C) insulation, IP00 open or IP20/IP23 enclosed, and AN or AN/AF cooling with a digital winding-temperature controller.

Why cast resin

  • HV coils vacuum-cast in epoxy resin with glass-fibre reinforcement — self-extinguishing, moisture-proof, partial discharge below 10 pC.
  • LV foil windings for high short-circuit strength; copper or aluminium conductor.
  • Forced-air fans add 40–50 % capacity for peak loads.
  • Standards: IEC 60076-11, GB/T 10228; climatic class C2, environmental E2, fire behaviour F1.

Compare with oil-immersed units in our specification guide, or size the unit with the calculator.

FAQ: Dry-Type Transformers

Where must a dry-type transformer be used instead of oil-immersed?

Most building codes require dry-type or non-flammable units inside occupied buildings, below ground, in high-rise electrical rooms, hospitals, data centres, airports and offshore. Wherever a fire-rated vault or oil containment is impractical, cast resin is the default choice.

What enclosure options are available?

IP00 open frame for installation in a switchroom, IP20 or IP23 sheet-steel enclosure with louvres, and IP31/IP44 sealed enclosures with forced cooling for dusty or humid sites. Enclosures can be integrated with the LV switchboard.

How much overload can a cast-resin transformer take?

With fans (AF cooling) a cast-resin unit typically delivers 140–150 % of its AN rating continuously. Short overloads follow IEC 60076-12 loading guides, controlled by the winding temperature relay.

Are the coils repairable?

Cast-resin coils are not rewindable on site; a damaged coil is replaced as a unit. This is rarely needed — the resin protects against moisture, dust and mechanical stress for the life of the transformer.