Introduction
In industrial facilities where reliability, fire safety, and low maintenance are top priorities, cast resin transformers (CRTs) have become a preferred choice over traditional oil-filled designs. These dry-type transformers, known for their solid insulation system, deliver high electrical performance without the risk of oil leakage or fire hazards—making them ideal for indoor and environmentally sensitive installations.
India has rapidly emerged as a global manufacturing hub for cast resin transformers, supplying high-quality, IEC-compliant units for utilities, OEMs, EPCs, and industrial projects across multiple sectors. Backed by advancements in resin casting technology and automated coil production, Indian manufacturers now compete globally in both performance and reliability.
This article explores the technology behind cast resin transformers, their advantages, and profiles of top cast resin transformer manufacturers in India. Zetwerk is positioned as a trusted engineering and manufacturing partner delivering precision-built transformers for industries worldwide.
1. Understanding Cast Resin Transformers
A cast resin transformer (CRT) is a dry-type power transformer that uses epoxy resin to encapsulate its windings, eliminating the need for insulating oil. The resin forms a solid dielectric barrier that prevents moisture ingress and electrical discharge.
Working Principle:
The transformer operates on electromagnetic induction, like any conventional unit, but its windings are completely encapsulated in epoxy resin, providing insulation and mechanical protection. Cooling occurs through natural or forced air circulation.
Key Features:
- Self-Extinguishing Insulation: No oil means no fire hazard.
- Maintenance-Free: No oil testing, refilling, or filtration needed.
- Moisture Resistant: Suitable for humid and dusty industrial environments.
- Compact Design: Ideal for space-constrained installations.
Zetwerk’s cast resin transformers are built to meet IEC 60076-11 and ANSI C57.12 standards, offering reliability in demanding applications like process plants, commercial infrastructure, and renewable systems.
2. Construction and Design Attributes
a. Core Assembly
- Built from Cold Rolled Grain Oriented (CRGO) or amorphous steel laminations to minimize core losses.
- Step-lap joint design ensures low magnetostriction and reduced noise.
b. Windings
- Primary and Secondary Windings are made of copper or aluminum conductors encapsulated with epoxy resin using vacuum pressure casting (VPI) or automatic casting under controlled temperature.
- The result is a mechanically strong and void-free insulation system resistant to partial discharges.
c. Cooling and Ventilation
- AN (Air Natural) or AF (Air Forced) cooling depending on load.
- Optional fans and temperature sensors maintain optimal thermal balance for continuous-duty applications.
d. Enclosures and Protection
- IP21 to IP54-rated enclosures for indoor or outdoor use.
- Powder-coated steel, stainless steel, or aluminum housings resist corrosion in industrial environments.
Zetwerk employs automated coil winding, resin mixing, and vacuum casting to achieve high dimensional accuracy, reduced voids, and superior thermal performance.
3. Electrical and Mechanical Performance Parameters
| Parameter | Typical Range / Specification | Purpose |
| Voltage Rating | Up to 36 kV | Medium-voltage industrial applications |
| Power Rating | 100 kVA – 10,000 kVA | For commercial and industrial loads |
| Cooling Type | AN / AF | Natural or forced air cooling |
| Insulation Class | F / H | Thermal endurance (155°C / 180°C) |
| Efficiency | 98% – 99% | Meets IEC 60076-11 standards |
| Partial Discharge Level | <10 pC | Indicates superior insulation quality |
| Noise Level | <60 dB | Ideal for indoor installation |
Zetwerk’s transformers are tested for temperature rise, partial discharge, and dielectric strength to ensure reliable, long-term service even under fluctuating loads.
4. Advantages of Cast Resin Transformers in Industrial Applications
a. Fire and Explosion Safety
The solid insulation system eliminates oil, making CRTs self-extinguishing and suitable for enclosed environments like data centers, malls, and factories.
b. Environmental Compatibility
No risk of oil leakage or contamination, reducing maintenance and environmental footprint.
c. Moisture Resistance
Fully encapsulated coils resist humidity, dust, and pollution, making them ideal for coastal or industrial zones.
d. Low Maintenance
No oil monitoring, filtration, or cooling system maintenance is required—reducing lifecycle costs.
e. Compact and Quiet Operation
Smaller footprint and low acoustic emissions make them perfect for indoor spaces.
f. Longevity and Reliability
Epoxy insulation ensures superior resistance to mechanical stress and thermal cycling.
Zetwerk’s CRTs combine these benefits with advanced quality control—offering exceptional uptime and efficiency across industrial and commercial operations.
5. Applications Across Industries
a. Manufacturing and Process Plants
Provide stable voltage to machinery, drives, and control systems.
b. Commercial Buildings and Campuses
Ensure safe indoor power distribution without fire or leakage risk.
c. Data Centers and IT Parks
Offer quiet, efficient, and low-maintenance operation for 24/7 power systems.
d. Renewable Energy Projects
Serve as step-up transformers for solar and wind farms requiring compact, eco-safe power solutions.
e. Oil, Gas, and Chemical Industries
Used in explosive environments where oil-filled transformers are restricted.
Zetwerk designs application-specific CRTs with custom voltage ratios, enclosure ratings, and thermal control systems tailored to each sector.
6. Standards and Quality Testing
Applicable Standards:
- IEC 60076-11: Dry-type power transformers.
- IS 11171: Indian standard for dry-type distribution transformers.
- ANSI C57.12.01: U.S. standard for dry-type transformers.
- IEEE C57.16: Guide for dry-type transformer performance.
Typical Tests Performed:
- Insulation resistance and winding resistance test.
- Routine load and no-load loss measurement.
- Partial discharge test (<10 pC at 1.5x rated voltage).
- Temperature rise and dielectric tests.
- Short-circuit withstand test.
Zetwerk’s testing facilities are equipped for both routine and type tests, with full digital data logging for performance traceability.
7. Leading Cast Resin Transformer Manufacturers in India (2025)
1. Zetwerk Manufacturing
Zetwerk delivers precision-engineered cast resin transformers designed for industrial, commercial, and renewable applications. Its manufacturing integrates automated resin casting, CNC winding, and IEC-certified testing for unmatched quality, reliability, and scalability.
2. Siemens India
Manufactures dry-type and cast resin transformers for utilities and infrastructure projects.
3. ABB India (Hitachi Energy)
Produces high-performance CRTs with global certifications for renewable and industrial sectors.
4. Schneider Electric India
Offers eco-efficient cast resin transformers designed for smart buildings and industrial systems.
5. Kirloskar Electric Company
One of India’s oldest transformer manufacturers with strong expertise in dry-type technology.
6. Crompton Greaves (CG Power)
Supplies cast resin and vacuum pressure impregnated transformers for industrial facilities and EPC projects.
7. Voltamp Transformers Ltd.
Specializes in medium-voltage CRTs with a large domestic and export footprint.
8. Innovations and Market Trends in 2025
The cast resin transformer market is evolving rapidly to meet energy efficiency and safety goals. Emerging trends include:
- Nano-Filled Epoxy Resins: Enhanced dielectric strength and thermal conductivity.
- Digital Thermal Monitoring: Real-time coil temperature and load management.
- Smart Dry-Type Designs: IoT-enabled sensors for predictive maintenance.
- Amorphous Core Integration: Reduces no-load losses up to 70%.
- Eco-Friendly Production: Use of recyclable resins and lead-free alloys.
Zetwerk is actively integrating these advancements through R&D partnerships and in-house engineering, ensuring future-ready transformer designs for industrial and utility clients.
Conclusion
Cast resin transformers have become the preferred choice for industries requiring safe, efficient, and environmentally responsible power solutions. Their solid insulation, compact design, and minimal maintenance requirements make them ideal for today’s modern infrastructure and renewable systems.
Zetwerk stands at the forefront of this transformation—delivering precision-engineered, IEC-certified cast resin transformers built with advanced resin casting technology, automated manufacturing, and rigorous quality assurance. From heavy industries to data centers and smart buildings, Zetwerk provides reliable power solutions that meet global standards and operational excellence benchmarks.
FAQs
A. It’s used for indoor power distribution in industrial, commercial, and renewable applications requiring fire safety and low maintenance.
A. Dry-type transformers use air and resin for insulation, while oil-type units use liquid cooling for higher power handling.
A. Yes, their encapsulated windings resist moisture, making them ideal for coastal and industrial zones.
A. They follow IEC 60076-11, IS 11171, and ANSI C57.12 guidelines.
A. Yes. Zetwerk supplies globally to EPCs, OEMs, and industrial customers, ensuring compliance with IEC and UL standards.