Zero Air Contact
Industrial Hermetically Sealed Transformers
Hermetically Sealed Transformers (also widely designated as Corrugated Tank Transformers) provide advanced oil-filled power distribution without reliance on atmospheric air exchange. Manufactured by Volta Transformers under strict ISO 9001:2015 quality standards, these units isolate dielectric liquid completely inside a fully welded, pressure-tested steel tank.
Unlike conventional oil-immersed transformers that utilize conservator tanks and silica gel breathers, hermetically sealed transformers eliminate direct atmospheric contact. Thermal expansion and contraction of the insulating mineral or synthetic ester oil are fully absorbed by elastic, precision-engineered corrugated cooling fins. This design prevents oil oxidation, sludging, and dielectric breakdown, offering a virtually maintenance-free operational life cycle across demanding B2B deployments.
Maintenance-Free Design
No silica gel replacement or oil filtration
Zero Contamination
Total isolation from moisture and pollutants
Extended Asset Life
Reduced dielectric degradation over decades
Compact Footprint
Saves site space in substations and enclosures
Key Features & Engineering Advantages
Engineered specifically for mission-critical infrastructure, industrial plants, and harsh ambient environments.
Minimal Maintenance Requirements
Eliminates routine fluid sampling, desiccant air-breather changes, and periodic oil degasification. Reduces operational expenditure (OPEX) over the entire transformer lifespan.
Advanced Thermal Corrugated Tank
Cold-rolled mild steel corrugated fins flex dynamically during thermal load changes, maintaining structural integrity and heat dissipation efficiency under full load conditions.
Corrosion-Resistant Coating
Tanks undergo multi-stage surface treatment, shot blasting, and high-durability polyurethane or epoxy paint finishing suitable for highly saline, tropical, and chemically aggressive ambient air.
Vacuum Degassing & Oil Filling
Insulating oil is processed, moisture-stripped, and injected under deep vacuum into the sealed tank. This guarantees zero trapped gas pockets and maximum dielectric breakdown strength (BDV).
Overpressure Protection Safety
Equipped with integrated overpressure relief valves (PRV) or multifunctional safety devices (such as RIS / DGPT2) monitoring internal pressure, temperature, and gas accumulation.
Compact Substation Compatible
Their compact dimensions make hermetically sealed transformers ideal for integration into prefabricated compact substations (CSS) and indoor package substations.
Standard Technical Specifications
Volta Hermetically Sealed Transformers are customized to meet international grid requirements and client engineering specifications.
| Specification Parameter | Standard Offering / Technical Range |
|---|---|
| Rated Power Capacity | 50 kVA to 5,000 kVA (5 MVA) |
| High Voltage (HV) Class | 1.1 kV, 3.3 kV, 6.6 kV, 11 kV, 13.8 kV, 22 kV, 33 kV, up to 66 kV |
| Low Voltage (LV) Class | 380 V, 400 V, 415 V, 433 V, 440 V, 600 V, 690 V (Custom available) |
| Frequency | 50 Hz / 60 Hz |
| Number of Phases | Three-Phase (Single-phase available upon request) |
| Cooling System | ONAN (Oil Natural Air Natural) via Corrugated Cooling Fins |
| Winding Material | High-grade Electrolytic Copper / EC Grade Aluminum |
| Insulation Fluid | High-grade Mineral Oil (IEC 60296) or Synthetic / Natural Ester Fluid |
| Insulation Class | Class A (Uniform / Graded insulation) |
| Vector Group | Dyn11, Dyn5, Ynd11, or as requested |
| Tap Changer | Off-Circuit Tap Changer (OCTC) / On-Load Tap Changer (OLTC) |
| Temperature Rise Limits | Oil: 50°C / 55°C / 60°C; Winding: 55°C / 60°C / 65°C |
| Standard Compliance | IEC 60076, IS 1180 (Part 1): 2014, IEEE C57, ISO 9001:2015 |
Applications Across Global Industries
Hermetically sealed transformers deliver operational confidence in locations where traditional maintenance access is costly or difficult.
Chemical & Refineries
Protected from corrosive gas exposure and chemical atmospheres.
Coastal & Marine
High resistance to humid, salt-laden marine environmental conditions.
Mining & Heavy Industry
Sealed against heavy dust ingress, vibration, and airborne particles.
Renewable Energy Plants
High reliability in remote Solar PV farms and Wind Turbine substations.
High-Rise & Commercial
Compact size and low risk profile suited for basement & indoor vaults.
Substations & Utilities
Low maintenance burden for power distribution networks.
Infrastructure Projects
Ideal for tunnels, railways, ports, and bridge power infrastructure.
Steel Mills & Foundries
Robust construction capable of withstanding heavy industrial load patterns.
Manufacturing Standards & Factory Testing
At Volta Transformers, our manufacturing plant in Vadodara, Gujarat is equipped with modern winding machines, vacuum drying ovens, and fully automated testing bays. Every Hermetically Sealed Transformer passes mandatory Routine Tests in accordance with IEC 60076 and IS 1180 standards before dispatch.
Routine Testing
Winding resistance, voltage ratio, phase displacement, no-load loss, load loss, and dielectric insulation testing.
Tank Leakage Test
Overpressure testing performed on every welded tank enclosure to verify absolute hermetic sealing.
Type Test Compliance
Temperature rise tests and lightning impulse withstand tests validated at independent certified laboratories.
Frequently Asked Questions
Common queries from B2B buyers and procurement engineers regarding Hermetically Sealed Transformers.
Require Hermetically Sealed Transformers for Your Project?
Contact our technical engineering sales team for detailed technical datasheets, dimensional drawings, and competitive direct factory quotations.