Vacuum Pressure Impregnated – VPI
Vacuum Pressure Impregnated (VPI) Dry Type Transformers are designed for reliable and efficient performance in demanding environments, both indoor and outdoor. These transformers use VPI insulation technology to enhance thermal performance and mechanical strength, making them suitable for industrial, commercial, and institutional applications. With ratings up to 5 MVA and voltage class up to 33 kV, they offer enhanced safety, reduced maintenance, and superior durability.
Assured Features
- Windings are electrically balanced to minimize axial & radial short circuit forces.
- Coils are held rigidly in place between insulators clamped to the upper and lower core frames under high compression.
- Polyester resin or thixotropic epoxy resin impregnation or silicon varnish, as per the application, is used.
- High-temperature resistant materials are used, including Nomex Aramid papers, silicone-coated fiberglass, and pressure-sensitive glass tape.
- Adequate ducts between coils, discs for maximum air flow, and reduced hot spot temperature. Step-lap designed CRGO laminations for lower losses and excitation current.
Technical Specifications
| Duty, Type | Outdoor / Indoor Ground Mounted Type |
| Ratings | UPTO 5 MVA |
| Voltage Class | UPTO 33 kV |
| No of Phases | 3 Phase |
| Frequency; | 50/60 Hz |
| Vector Group | Dyn1 or Dyn5 or Dyn11 or any specific |
| Class of Insulation | F or H with Temp Rise of 90 or 115 Deg C or as per customer requirement |
| Tap Changer Type | Off Circuit Type or On Load Type |
| Tapping Range | + 2.5% X 2 for OFF CIRCUIT TAP CHANGER or + 2.5% X 2 & – 2.5% X 6 for ON LOAD TAP CHANGER or as per customer requirement |
| Winding Material | Aluminium Or Copper with multi paper NOMEX-ARAMID covering |