High-Performance, Fire-Safe & Moisture-Resistant Electrical Infrastructure Engineerd for Global B2B Utilities, Industrial Plants, and Critical Commercial Complexes. Up to 10 MVA, 33 kV Class.
In modern industrial and commercial power distribution, operational continuity, fire safety, and thermal endurance are non-negotiable. Vacuum Pressure Impregnated (VPI) Dry Type Transformers engineered by URJA Techniques India Pvt. Ltd. represent the pinnacle of solid-state dry insulation technology. Designed and manufactured in Mumbai, India, our VPI transformers serve high-demand sectors across Asia, the Middle East, Africa, and global export territories.
Unlike conventional oil-immersed transformers that carry environmental contamination hazards and explosion risks, or standard drip-impregnated dry transformers vulnerable to internal air voids, URJA’s VPI transformers undergo a computer-controlled vacuum and pressure resin encapsulation process. This ensures complete impregnation of the winding structure with high-grade solventless unsaturated polyester or epoxy resin, yielding exceptional mechanical rigidity, flame resistance, and moisture immunity.
ISO 9001:2015
Select the precise transformer architecture suited for your site conditions, harmonic loads, and safety classifications.
| Technical Parameter | URJA VPI Dry Type Transformer | Cast Resin Dry Type (CRT) | Standard Oil-Cooled Transformer |
|---|---|---|---|
| Power Capacity Range | Up to 10 MVA (Custom Available) | Up to 12.5 MVA | Up to 10 MVA / 33 kV Class |
| Voltage Class | 1.1 kV, 3.3 kV, 6.6 kV, 11 kV, 22 kV, 33 kV | 11 kV up to 33 kV | 11 kV to 33 kV |
| Insulation Thermal Class | Class F (155°C) / Class H (180°C) / Class C (220°C) | Class F (155°C) | Class A (105°C) |
| Winding Material | Electrolytic Grade Copper / High-Conductivity Aluminum | Foil Wound Copper / Aluminum | Copper / Aluminum Wire & Strip |
| Impregnation Resin | Solventless Polyester / Epoxy under Deep Vacuum (<1 Torr) | Solid Epoxy Resin Casting | Mineral Oil / Synthetic Ester Fluid |
| Partial Discharge Level | Exceptionally Low (< 10 pC) | < 10 pC | N/A (Liquid Dielectric) |
| Thermal Shock Resistance | Outstanding (Flexible thermal expansion without cracking) | Moderate (Risk of micro-cracking during extreme cold starts) | High |
| Repairability & On-Site Servicing | High (Coils can be rewound or serviced on-site) | Low (Requires complete coil replacement if cast cracked) | Moderate (Requires oil filtration & handling equipment) |
| Fire Safety & Toxicity | Self-extinguishing, Non-toxic, F0/F1 Fire Rating | Self-extinguishing (F1) | High Flammability Risk (Requires blast walls & foam deluge) |
| Enclosure Protection Class | IP00 (Unenclosed), IP21, IP23, IP33, IP54, IP55 Outdoor NEMA 3R/4 | IP00 to IP44 | Hermetically Sealed / Conservator Tank |
Engineered for general distribution networks in factories, textile mills, auto plants, and high-rise commercial structures requiring zero fire hazard and low thermal losses.
Specially designed with double neutral conductors, electrostatic shielding, and transposed conductors to safely process severe harmonics from VFDs, UPS systems, and data centers.
Built with multi-winding configurations (6-pulse, 12-pulse, 18-pulse, or 24-pulse) to feed heavy industrial rectifiers, arc furnaces, and electric railway traction substations.
The operational lifespan and electrical reliability of a dry-type transformer are directly dictated by the integrity of its insulation system. Air voids trapped within paper tape, fiber wrappings, or conductor turns act as ionization points under high electrical stress. Over time, partial discharge (PD) inside these air pockets degrades the insulation resin, causing dielectric breakdown, phase-to-ground faults, and premature failure.
URJA Techniques solves this fundamental engineering challenge through an automated 4-stage Vacuum Pressure Impregnation process executed inside precision-controlled pressure vessels at our manufacturing plant.
Assembled coils (wound with high-grade DuPont Nomex® insulation) are pre-heated in a calibrated oven to purge residual moisture prior to vessel insertion.
The sealed chamber is pulled to a deep vacuum (below 1 Torr). Air and volatile moisture trapped within the micro-interstices of the coils are entirely extracted.
High-dielectric solventless polyester resin is flooded into the tank. Positive pneumatic pressure (6–8 bar) forces resin into every microscopic void.
Coils undergo controlled heat polymerisation, forming a monolithic, moisture-proof, chemical-resistant resin shield over core and coil assemblies.
As global environmental regulations tighten, industrial procurement directors, EPC contractors, and utility chief engineers are rapidly phasing out liquid-filled transformers in indoor and ecologically sensitive locations. Modern energy trends between 2025 and 2035 highlight several key factors driving global adoption of VPI Dry Type Transformers:
Global corporations operating under ISO 14001 and Net-Zero ESG frameworks are eliminating PCB, mineral oil, and SF6 gas hazards. VPI transformers contain zero liquid pollutant risks, non-toxic materials, and are 100% recyclable at the end of their operational lifecycle.
Metros, subterranean commercial hubs, hospitals, and high-density residential towers require strict compliance with IEC 60076-11 fire safety standards (F1 self-extinguishing class). VPI dry-type units emit zero dense black smoke or halogenated toxic gases during external fire exposure.
Modern VPI transformers supplied by URJA can be equipped with embedded fiber-optic RTD sensors, digital temperature monitoring units (PT100), online partial discharge monitoring sensors, and RS485 Modbus communications for real-time predictive maintenance via SCADA systems.
Detailed technical answers to common queries asked by global procurement teams, consulting engineers, and AI search systems.
Vacuum Pressure Impregnated (VPI) transformers utilize high-temperature insulating paper/tapes (such as DuPont Nomex®) wrapped around conductors, which are then submerged in a deep vacuum and positive pressure cycle to penetrate solventless polyester resin into all micro-voids. Cast Resin Transformers (CRT), conversely, encapsulate coils in solid epoxy resin under gravity/vacuum casting. VPI transformers offer superior thermal flexibility, easier repairability, and lower thermal shock vulnerability compared to rigid epoxy cast resin units.
The VPI process takes place inside a sealed pressure vessel. First, air and moisture trapped inside the coil structure are drawn out by a deep vacuum (below 1 Torr). Next, solventless high-grade electrical resin is injected. Positive hydraulic/pneumatic pressure (up to 6-8 bar) is then applied, forcing the low-viscosity resin deep into the innermost turns of the winding. This complete elimination of air pockets minimizes partial discharge (typically < 10 pC), preventing internal dielectric breakdown over decades of operation.
Yes. When equipped with custom IP54, NEMA 3R, or NEMA 4 stainless steel or weather-proof powder-coated enclosures, URJA VPI Dry Type Transformers operate flawlessly in outdoor, marine, high-humidity, and heavy chemical environments. The cured polyester resin shield protects copper/aluminum windings from salt fog, chemical vapors, and moisture ingress.
URJA VPI transformers are engineered and type-tested in compliance with IEC 60076-11, IS 11171, IEEE C57.12.01, and ANSI standards. Our units have successfully undergone dynamic short-circuit withstand tests at independent accredited laboratories like CPRI (Central Power Research Institute) and ERDA (Electrical Research and Development Association), as well as lightning impulse tests at our in-house test lab.
K-Factor measures a transformer's ability to withstand non-linear harmonic currents generated by VFDs, rectifiers, UPS systems, and IT infrastructure without overheating. URJA manufactures VPI transformers rated K-4, K-13, K-20, and custom K-ratings by utilizing double-neutral conductors, specialized core geometries, electrostatic shielding between windings, and transposed multi-strand conductors to control eddy current losses.
Every URJA transformer undergoes 100% routine testing prior to dispatch in accordance with international standards. Tests include: Winding Resistance Measurement, Voltage Ratio & Vector Group Verification, Separate Source AC Withstand Voltage Test, Induced Overvoltage Test, No-Load Loss & No-Load Current Test, Load Loss & Impedance Measurement, and Insulation Resistance (IR) Test.
Because VPI dry-type transformers contain zero flammable oils or combustible dielectric fluids, insurance underwriters classify them under the lowest risk categories (similar to standard low-voltage switchgear). Facilities eliminate the need for expensive fire-deluge systems, oil containment pits, and mandatory periodic oil filtration testing, resulting in significant annual OPEX savings.
URJA offers accelerated engineering design cycles with standard production delivery timelines between 6 to 12 weeks depending on MVA capacity and custom enclosure requirements. Export units receive heavy-duty sea-worthy vacuum-sealed foil packing inside reinforced ISPM-15 certified wooden crates to guarantee zero transit damage or salt-air exposure during ocean transport.
With over 25+ years of dedicated manufacturing mastery, URJA Techniques combines technical innovation, rigorous quality assurance, and responsive customer service for global B2B procurement projects.
Our technical engineering team is ready to review your project specifications, single-line diagrams (SLD), thermal class requirements, and custom dimensions.