As electrification, renewable energy integration, data centre growth, and grid modernization accelerate worldwide, demand for reliable transformers and high-voltage equipment continues to increase. Electrical equipment manufacturers and electrical power distribution companies face increasing pressure to improve reliability, efficiency, and sustainability. From power transformers, bushings, and cables to vacuum-insulated breakers, electrical motors, and high-voltage components, one challenge remains central: removing moisture effectively while protecting insulation integrity.
Moisture is one of the greatest enemies of electrical insulation. Even small amounts of residual water can significantly reduce dielectric strength, accelerate insulation ageing, increase partial discharge activity, and ultimately lead to equipment failure. This is where advanced vacuum technology plays a critical role.
Why Vacuum Technology matters in Electrical Applications?
Vacuum technology plays a pivotal role throughout the electrical manufacturing and maintenance processes. Whether drying transformer insulation, degassing transformer oil, impregnating paper insulation, or recovering SF₆ gas from high-voltage switchgear, achieving a deep and stable vacuum is essential for product quality, operational safety, and long-term reliability.
Vacuum technology enables electrical manufacturers and operators:
- Remove moisture from insulation systems
- Improve dielectric performance
- Extend equipment lifetime
- Accelerate manufacturing processes
- Reduce maintenance requirements
- Ease maintenance operations
- Improve energy efficiency
- Meet increasingly stringent environmental regulations
With the right vacuum technology, electrical components manufacturers and power distribution companies can significantly improve moisture removal while reducing cycle times and operating costs.
Key Vacuum Applications in the Electrical Industry
- Transformer Drying
- Oil Degassing
- Oil and Resin Impregnation
- High-Voltage Bushings and Electrical Components
- SF₆ Recovery and Gas Handling
Transformer Drying
Transformer drying is one of the most demanding vacuum applications in the electrical sector. Vacuum technology plays a critical role both during transformer production and throughout the maintenance lifecycle, helping manufacturers achieve high insulation quality and enabling service teams to restore transformer reliability after repair or in-field operation.
The reliability of a transformer depends heavily on the moisture content of its insulation system. Excess moisture reduces dielectric strength and significantly increases the risk of electrical failure. During manufacturing, vacuum is used to remove moisture from coils, insulation materials, cores and windings before oil filling. In maintenance applications, vacuum also supports drying after repairs, as well as oil purification and degassing to help extend transformer service life.
Vacuum technology is used across several transformer drying processes:
Coil Pre-Drying - Transformer coils and insulation materials are pre-dried under vacuum before final assembly, improving process efficiency and product quality. Modern transformer manufacturers increasingly rely on dry vacuum technologies to reduce drying times and eliminate contamination risks associated with traditional oil-sealed pumps.
Vapour Phase Drying (VPD) - Used mainly during transformer production for new insulation, VPD combines heat, vacuum and kerosene or similar hydrocarbon vapours to achieve deep moisture extraction from large transformer cores and windings. The vapour transfers heat efficiently into the insulation system, while the vacuum removes water vapour and residual solvent through condensers for separation and recovery. Typical operating pressures range from 10-120 mbar during heating stages down to below 0.2 mbar during final drying.
Hot Oil Spray (HOS) - Used mainly in maintenance applications, heated transformer oil is circulated or sprayed through the transformer while vacuum removes evaporated moisture. This combination of heat and vacuum accelerates moisture removal after repair or service operations.
Vacuum Drying - Used for final moisture removal and leak testing before oil filling. Drying systems typically reach pressures below 0.1 mbar to ensure optimum insulation quality and support reliable oil impregnation.
Oil Degassing
Insulating oil plays a vital role in transformer cooling and electrical insulation. Over time, dissolved gases, moisture, and contaminants degrade oil performance.
Vacuum oil degassing systems remove:
- Dissolved moisture
- Oxygen
- Hydrogen
- Hydrocarbon gases
- Other contaminants
The result is improved dielectric strength, enhanced transformer efficiency, and reduced risk of unplanned outages.
Edwards dry vacuum systems are particularly suitable for transformer oil purification thanks to their oil-free operation and ability to handle continuous vapor loads without contamination.
Oil and Resin Impregnation
Vacuum impregnation processes are widely used in the production of:
- Oil Impregnated Paper (OIP) bushings
- Resin Impregnated Paper (RIP) insulation
- Capacitors
- Motor windings
- High-voltage electrical components
Vacuum removes trapped air and moisture before impregnation, allowing insulating media to penetrate deep into the material structure, improving dielectric performance and long-term reliability.
Operational impact
Reduce repair lead times and unplanned downtime
Extend pump lifetime and lower cost of ownership
Enhance process stability with accurate calibration results
Support long‑term maintenance planning and digital service tools
Improve operator skills and safety through structured training
Increase equipment reliability
Whether you need a vacuum pump repair, certified calibration or practical technical training, our workshops are ready to support you.
Contact us to discuss your needs
Bushings, capacitors, switchgear components, and epoxy-insulated assemblies require precise moisture control throughout manufacturing.
Vacuum Pressure Impregnation (VPI) is used for the production of electrical components such as motors, generators and stators.
Vacuum is also used for cable manufacturing and drying.
Typical vacuum drying conditions include:
- Pressure: 0.1–10 mbar
- Temperature: 40–120°C
- Cycle duration: several hours to several days
Accurate vacuum control helps prevent cracking, partial discharge activity, and premature insulation ageing, ensuring product quality and compliance with industry standards.
SF₆ Recovery and Gas Handling
Sulfur hexafluoride (SF₆) has been used for decades as an insulating and switching gas in high-voltage equipment (e.g., GIS switchgear, circuit breakers). It has excellent electrical properties and high chemical stability.
However, SF₆ is an extremely potent greenhouse gas (Global Warming Potential ≈ 23,500 × CO₂) and very long-lived in the atmosphere. Its use is therefore increasingly subject to regulatory pressure (e.g., EU F-Gas Regulation). That makes recovery and recycling increasingly important.
Vacuum systems play a critical role in:
- Gas evacuation
- Recovery and recycling
- Leak testing
- Switchgear maintenance
- End-of-life decommissioning
Edwards dry screw vacuum pumps provide contamination-free gas handling and high recovery rates while supporting compliance with evolving environmental regulations.
Common challenges in Electrical Vacuum Processes
Electrical components manufacturers and power distribution companies face several recurring challenges:
Long drying cycless
Large transformers often require drying cycles lasting several days, creating production bottlenecks and increasing operating costs.
High moisture and vapor loads
Vacuum stability
Maintenance demands
Regulatory compliance
Environmental regulations continue to increase requirements around emissions, safety, ATEX compliance, and SF₆ handling.
Mobile Service Operations
Field drying and maintenance applications require robust, portable vacuum systems capable of operating in demanding outdoor environments.
Get more details on these common operational challenges.
Know more about these operational challenges associated with drying transformers and high-voltage components, and understand how Edwards Vacuum Solutions help to address them.
Why choose Edwards Vacuum Solutions?
Edwards combines several decades of vacuum technology expertise with state-of-the-art dry vacuum technology that is particularly well suited to demanding electrical applications.
Enhanced process stability
Consistent vacuum performance improves operations and process reliability and ensures repeatable results.
Mobile Solutions
From factory-installed systems to mobile transformer service units and fully containerised installations, Edwards delivers solutions for every operating environment.
Global Service and Support Network
Edwards set a local expertise backed by a worldwide Edwards service network.
Process robustness
Edwards dry vacuum pumps are designed to handle vapours, solvents, particulates and corrosive by-products without compromising performance.
Oil-Free Technology
Edwards is a pioneer in dry vacuum technology which eliminate the risk of oil contamination while reducing maintenance requirements and improving operational reliability.
ATEX and safety compliance
Solutions are available with internal and external ATEX certification options for hazardous environments.
Faster drying cycles
Stable deep vacuum enables faster moisture removal, reducing drying times and increasing throughput.
Complete Vacuum range
Edwards supplies vacuum pumps and systems, boosters, skids, mobile systems tailored to fit electrical applications.
Lower lifecycle costs
Reduced maintenance requirements, increased uptime, and improved energy efficiency contribute to lower costs.
Whether you manufacture high-voltage equipment, operate transformers and bushings, perform oil degassing, or recover SF₆ gas, Edwards can help you.