What a dry cast resin transformer Actually Is

A dry cast resin transformer is a dry-type distribution transformer whose high-voltage and low-voltage windings are encapsulated in epoxy resin under vacuum casting. There is no oil tank, no conservator and no insulating liquid anywhere in the unit. Air, combined with the solid cast insulation, does the insulating and cooling work, which is exactly why the product is called a dry cast resin transformer rather than a liquid-filled one.

For a procurement engineer, that single design decision changes almost everything downstream: fire behaviour, installation location, maintenance routine, footprint and lifetime cost. It is also why the model is now the default choice for indoor substations in commercial buildings, hospitals and industrial plants.

How the Construction Works

• High-voltage winding: copper conductor cast in epoxy resin under vacuum, giving a void-free, moisture-proof insulation body with strong short-circuit withstand strength.
• Low-voltage winding: foil or wire wound, cast or resin-coated depending on the series and capacity.
• Insulation class: typically class F (155 degrees C) or class H (180 degrees C), with temperature rise limits set accordingly.
• Cooling: AN (natural air) as standard, with AF (forced air) fans available as an option to raise capacity when peak loads require it.
• Enclosure: IP20 for indoor installation, IP23 or higher when dust or water ingress is a concern.
• Standards: GB/T 10228 for dry-type power transformers, IEC 60076-11, and GB 20052 for energy efficiency grades.

Reading the Model Codes: SCB10, SCB13, SCB14, SCB18

The letters describe the design, and the number describes the loss level. S means three-phase, C means cast resin, and B indicates a foil-type low-voltage winding. The figure that follows is the performance code, and higher generally means lower no-load loss and lower load loss.

• SCB10 dry-type transformer: an older efficiency tier, still found in legacy projects.
• SCB13 dry-type transformer: a widely used mainstream tier for standard 10 kV and 20 kV distribution work.
• SCB14 dry-type transformer: a higher efficiency tier that many new projects now specify.
• SCB18 dry-type transformer: a top efficiency tier for projects with strict energy targets.

Capacity range typically runs from 30 kVA up to 2500 kVA in standard builds, with larger units possible on request, at voltage classes of 10 kV, 20 kV and 35 kV.

Why Buyers Choose It Over Oil-Immersed Units

• Fire safety: no flammable liquid, so it can be installed inside buildings, basements and densely occupied areas without a separate fire-rated chamber.
• Maintenance: no oil sampling, no oil filtering, no leakage repair. Routine work is limited to cleaning and checking connections and the temperature controller.
• Footprint: compact dimensions suit space-constrained electrical rooms.
• Environmental performance: low no-load loss and low noise, often in the 30 to 55 dB range depending on capacity.
• Moisture and dust resistance: the sealed cast body performs well in humid or polluted environments.

The trade-off is a higher purchase price than a comparable oil-immersed transformer. In most indoor and renewable energy projects the saving on civil works, fire protection and maintenance pays that difference back within a few years.

Where It Is Used

Typical applications include commercial complexes, hospitals, data centres, metro and airport facilities, water treatment plants, and industrial production lines. It is also common in renewable energy transformer packages for solar and wind farms, where indoor or containerised installation and low fire risk are decisive factors.

How to Choose Without Overpaying

• Match the efficiency tier to local regulation. Buying SCB18 where SCB13 is permitted spends money you never recover; buying below the minimum grade risks failing inspection.
• Confirm the winding conductor material in writing. Copper and aluminium units look similar from the outside.
• Fix the IP rating and cooling method before quoting, since enclosure and fans affect both price and delivery.
• Require routine test reports, a temperature rise record and a certified nameplate layout with the offer.
• Verify that the supplier actually manufactures the unit rather than reselling it, so that warranty and spare parts remain traceable.

What Drives the Price

• Conductor content, which follows both capacity and efficiency level
• Rated capacity from 30 kVA to 6300 kVA and voltage class up to 35 kV
• Accessories such as temperature controllers, cooling fans and enclosures
• Third-party inspection, type-test certificates and non-standard dimensional requirements

Sourcing Direct From the Manufacturer

Runsheng Transformer Co., Ltd. produces a full range of dry-type and oil-immersed equipment, including SCB10, SCB13, SCB14 and SCB18 cast resin units, the SGB10 series, SH15 and SCBH15 amorphous alloy transformers, S11, S13, S20 and S22 oil-immersed transformers, mining and rectifier transformers, and 35 kV and below preassembled substations, compact substations plus high and low voltage switchgear. Units are built to national standards and shipped with manuals, inspection reports, test certificates and lifelong quality tracking, with oil-immersed and dry-type models available at factory-direct prices from maintained inventory.

For buyers who want a fast quotation on capacity, efficiency tier, voltage class and enclosure, contact: phone +86 13406394988, e-mail runsheng@7813transformer.com, WhatsApp 008613508930968.