The mobile vapor-phase drying equipment (MVPD) realizes the vision of “bringing the factory to the power station,” enabling factory-level inspection and maintenance of transformers directly at the site.

MVPD Highlights

• No need to return faulty transformers to the factory – on-site condition monitoring and vapor-phase drying.

• Perfect for field-assembly power transformers drying and testing.

• Superior drying performance – reduces moisture from solid insulation to <0.5%, greatly extending transformer service life. This level of dryness cannot be achieved by existing on-site drying processes such as Mobile LFH, hot-oil spray under vacuum, or hot-oil circulation under vacuum.

• Modular structure – compact design with no excess height or width, ensuring easy transportation.

• Reduced downtime – significantly shortens transformer outage periods by enabling on-site factory-level drying.

• Cost savings – eliminates high transportation expenses associated with sending transformers back to the factory.

• Lower risk – removes the risks of damage during transport.

• Faster process – treatment time is considerably shorter compared with any other on-site drying technologies, thus a much faster on-site inspection.

Advantages of MVPD over Stationary VPD (with respect to site conditions)

• Quick on-site setup – Before the drying process, only a few flexible metal pipes (corrugated tubes) need to be connected between the MVPD modules and the transformer’s oil tank, along with the supply power and cooling water pipes.

• Shorter drying time – It only takes 3-4 days to dry a 110kV transformer;

  4-5 days for 220kV transformer;

  8 days for a 500kV/750MVA transformer;

  9 days for a 500kV/1000MVA transformer.

• Double-evaporator design for efficient drying process – For transformers requiring multiple distillation cycles (often more than ten), the double-evaporator design plays a crucial role in enhancing drying performance and accelerating the process..

• Equivalent drying process and performance to stationary VPD – the winding temperatures can reach up to 128°C, core temperatures up to 120°C, ultimate vacuum below 10 Pa, and the moisture content of the insulation sample reduced to <0.5%.