Vacuum Pressure Impregnation for Power Transmission & Distribution

Vacuum pressure impregnation removes air and moisture from insulation materials before introducing oil under controlled pressure. This process fills internal voids that standard coating methods cannot reach.

The typical VPI cycle follows several controlled stages:

• Vacuum phase. Air and moisture are removed from winding insulation and porous materials.
• Oil introduction. Insulating oil enters the chamber under vacuum to penetrate internal structures.’
• Pressure cycle. Positive pressure forces oil deep into insulation layers for full saturation.

This method is used with transformer insulation systems where consistent dielectric strength is required across the entire component.

Advantages of integrating VPI into the manufacturing process include:

• Higher dielectric strength. Resin fills the microscopic voids that otherwise lead to partial discharge.
• Thermal stability. Uniform resin distribution reduces the risk of hot spots under heavy loads.
• Environmental resistance. Sealed insulation systems limit the ingress of water and contaminants over time.

At The Imprex Division of Godfrey & Wing, our processes enable transformer reliability and reduce the risk of insulation breakdown in environments characterized by fluctuating loads and harsh environmental exposure.

Dry-type systems rely heavily on insulation performance because they lack the cooling and dielectric benefits of liquid fluids. In these systems, incomplete impregnation leads to rapid insulation degradation.

The Imprex Division of Godfrey & Wing’s resin impregnation technology improves dry-type transformer reliability by creating a uniform barrier that protects against moisture, dust, and contaminants. The process also dampens vibration and movement during operation, which prevents the mechanical wear that often weakens insulation over time.

Vacuum pressure impregnation supports various power transmission and distribution assets where insulation integrity is a primary concern. Manufacturers can utilize VPI transformers for:

• Utility transformers on distribution networks
• Substation equipment exposed to extreme environmental stress
• Renewable energy systems (i.e., wind and solar) with variable load conditions
• Industrial power systems operating in corrosive or high-vibration environments
• Transportation and EV charging electrification infrastructure

In these applications, vacuum pressure impregnated transformers provide the durability required where standard insulation methods often fail.

As electrical grids become more complex, insulation performance plays a larger role in system stability. Engineers working on modern infrastructure increasingly specify transformer insulation systems that can maintain performance across extended service intervals.

The Imprex Division of Godfrey & Wing offers VPI equipment and services to improve insulation consistency and reduce failure risks tied to partial discharge or thermal stress. Our VPI technology complements existing insulation systems by entirely filling internal gaps and eliminating porosity defects. This leads to more stable long-term operation, even under cyclic thermal loads and harsh environmental conditions.

The Imprex Division of Godfrey & Wing specializes in VPI solutions for modern requirements, including custom equipment, high-performance sealants, and contract services. Our systems remove air and moisture from transformer insulation and replace them with controlled oil or resin impregnation for repeatable, high-quality results.

When your application requires enhanced dielectric performance, we can help you evaluate the right VPI approach for your production line. Contact us to discuss your transformer insulation requirements or to request technical guidance on implementing vacuum pressure impregnation in your facility.