Capacity Range: 100 kVA to 10 MVA
Voltage Class: Up to 33 kV
Frequency: 50 Hz
Insulation Class: F (155°C) or H (180°C)
Cooling Methods: AN (Air Natural) / AF (Air Forced)
Standards: IS 11171 / IEC 60726
Winding Material: Copper / Aluminium
A Cast Resin Dry Type Transformer is one of the most advanced and safest power distribution solutions available today. Unlike conventional oil-filled transformers, it uses epoxy resin to encapsulate the windings — eliminating fire hazards, reducing maintenance costs, and making it ideal for indoor and sensitive environments. Whether you are planning a metro station, a hospital, a data center, or a large commercial building, this transformer delivers exceptional performance with zero oil leakage and minimal environmental impact.
As India’s power infrastructure rapidly modernises and the demand for energy-efficient equipment grows, the cast resin dry type transformer has become the preferred choice across industries. In this guide, we cover everything you need to know — from working principles and specifications to key applications and pricing.
A Cast Resin Dry Type Transformer is an electrical transformer in which both the primary and secondary windings are completely encapsulated in a solid epoxy resin casting. This solid insulation replaces the liquid dielectric (oil) used in conventional transformers, making it a genuinely dry, maintenance-free, and environmentally friendly solution.
The epoxy resin provides outstanding mechanical strength, resistance to humidity, and excellent thermal performance. The result is a transformer that can operate reliably in harsh environments — coastal areas, chemical plants, underground substations, and high-altitude installations — where oil-based transformers would require constant supervision.
If you are comparing options, you may also want to read our detailed guide on the difference between power transformer and distribution transformer to understand which solution best fits your project requirements.
The Cast Resin Dry Type Transformer manufactured at Tirupati Transformer comes with a robust set of features that meet the most stringent industrial and commercial standards:
The operating principle is identical to any two-winding transformer — electromagnetic induction transfers energy from the primary coil to the secondary coil. What sets the cast resin variant apart is its insulation system.
In a Cast Resin Dry Type Transformer, both coils are cast under vacuum in a mould filled with epoxy resin mixed with hardener and filler. Once cured, the resin forms a solid, void-free block that tightly binds the conductors. This eliminates partial discharges caused by air gaps, extends dielectric life, and dramatically reduces the risk of insulation failure due to moisture, dust, or contaminants.
Cooling is achieved entirely through natural air convection (AN cooling) or, in higher-capacity units, through forced air (AF cooling) using integrated fans. No oil, no radiators, no Buchholz relay — just clean, efficient air cooling.
The Cast Resin Dry Type Transformer is widely deployed across sectors that demand safe, compact, and low-maintenance power equipment:
Metro rail networks in Delhi, Mumbai, Bengaluru, and Hyderabad rely on cast resin dry type transformers for traction power supply and auxiliary distribution. Their fire-resistance and compact form factor are critical in confined underground tunnels.
Uninterrupted power is non-negotiable in hospitals. The zero-maintenance and fire-safe nature of these transformers makes them ideal for powering operation theatres, ICUs, and critical diagnostic equipment.
Data centres require transformers that produce minimal electromagnetic interference and operate silently at high efficiency. The low noise and compact design of epoxy-cast transformers perfectly meet these requirements.
With India targeting 500 GW of renewable capacity by 2030, the cast resin dry type transformer plays a vital role as solar inverter duty and wind farm step-up transformers. Their ability to handle frequent load variations and operate outdoors without oil makes them the preferred choice for green energy projects. Learn more about our solar inverter duty transformer.
In high-rise buildings and malls where transformer rooms are close to occupied areas, the zero-oil design eliminates explosion risk and keeps insurance premiums lower.
Many buyers wonder how a Cast Resin Dry Type Transformer compares with the traditional oil-filled counterpart. Here is a clear comparison:
Fire Safety: Cast resin is self-extinguishing and produces no flammable vapour. Oil-filled transformers require a separate fire-suppression system and a dedicated oil pit.
Maintenance: Cast resin units require virtually no scheduled maintenance. Oil-filled units need oil sampling, filtration, and periodic replacement.
Environment: Zero oil means zero risk of soil or water contamination — a critical factor near water bodies or in urban areas.
Installation: Cast resin units can be installed indoors, in basements, on rooftops, and in confined spaces without special civil provisions.
Cost: The initial cost of a cast resin unit is higher, but the total cost of ownership — when you factor in maintenance, fire protection, and insurance — is significantly lower over a 20-year asset life.
For a detailed technical reference, visit the Bureau of Energy Efficiency (BEE) India official portal, which publishes efficiency class requirements for dry type transformers in India.
Tirupati Transformer is a leading manufacturer and supplier of Cast Resin Dry Type Transformer in India, operating from Greater Noida with 10+ years of industry experience. Here is why thousands of clients across India trust us:
Explore our full range of transformer products including distribution transformers, power transformers, and VPI transformers.
A well-maintained Cast Resin Dry Type Transformer can last 25 to 30 years. The epoxy resin insulation does not degrade with moisture, and because there is no oil to oxidise or leak, the insulation system remains stable over decades of continuous operation.
Yes, with an appropriate IP54 or IP65 weatherproof enclosure, these transformers can be installed outdoors. The resin insulation itself is highly resistant to UV radiation and temperature swings.
Absolutely. Tirupati Transformer offers K-rated and derating options specifically designed for non-linear loads such as variable frequency drives, UPS systems, and rectifiers — common in data centres and manufacturing plants.
In India, cast resin dry type transformers are governed by IS 11171 (Bureau of Indian Standards) and internationally by IEC 60076-11. Tirupati Transformer complies with both standards and can provide test certificates for all supplied units.
Investing in a high-quality cast resin transformer is a long-term decision that pays dividends through lower maintenance costs, higher safety, and superior reliability. Whether your requirement is for a metro project, a renewable energy plant, a data centre, or a commercial complex, Tirupati Transformer has the right solution — engineered to Indian standards, backed by over a decade of manufacturing excellence.
Ready to get started? Contact us today for a free consultation and customised quotation.
| Brand | Tirupati Transformer | |
| Rating | Upto 10 MVA | |
| Applicable Standards | IS, IEC, BIS etc. | |
| Cooling | ONAN, ONAF | |
| Insulating Fluid | Mineral Oil To Specification | |
| Frequency | 50 Hz, 60 Hz | |
| Primary Voltage | 11KV/ 22 KV/ 33 KV | |
| Winding Material | Copper | |
| ping | On Load Tap Changer, Off Circuit Tap Changer | |
| Impedance | Upto 8.35%, tolerance +10% | |
| Insulation | Class ‘A’ | |
| Rated Voltage | HV | 33 KV |
| LV | 11 KV | |
| Highest Continuous system voltage | Maximum system voltage ration (HV/LV) | 36 KV / 12 KV |
| Rated Voltage Ration (HV/LV) | 36 KV / 11 KV | |
| Method of Connection | HV | Delta |
| LV | Star |