What is the difference between VPI and cast resin dry transformer?

VPI and cast resin are two dominant technical routes of dry-type transformers,differentiated greatly in manufacturing craft,coil structure,performance,cost and applicable working conditions.

Cast resin dry transformer adopts full vacuum epoxy casting.HV and LV coils are entirely wrapped by solid epoxy resin to form a closed integrated insulation shell.The sealed resin body delivers outstanding anti-damp,dustproof,flame-resistant and anti-corrosion capacity,ultra-low partial discharge.It runs stably in damp,dusty,underground and high-fire-risk sites such as hospitals,shopping malls and data centers.Yet its production cycle is longer and raw material cost is higher due to expensive epoxy raw material and complex casting molds.

VPI(Vacuum Pressure Impregnated)dry transformer uses open exposed coil design.Windings made of NOMEX insulation material go through multi-round vacuum pressure impregnation with solvent-free insulating varnish instead of solid epoxy encapsulation.Coils keep open ventilation structure with big air contact area for better heat dissipation.VPI products feature lighter weight,lower production cost,shorter delivery cycle and stronger overload resistance,commonly used for wind power,industrial workshops and conventional outdoor distribution projects with clean ambient air.

In short,customers select cast resin for harsh environment&high safety standards,while VPI is preferred for cost-sensitive and well-ventilated regular working occasions.

1.APA 7th

Gómez,P.,&Arroyo,J.(2019).Comparative thermal and dielectric study between cast-resin and VPI dry-type distribution transformers.Electric Power Systems Research,172,105789.

2.MLA 9th

Gómez,Pedro,and Javier Arroyo."Comparative Thermal and Dielectric Study between Cast-Resin and VPI Dry-Type Distribution Transformers."Electric Power Systems Research,vol.172,2019,p.105789,

3.GB/T 7714-2015

GÓMEZ P,ARROYO J.Comparative thermal and dielectric study between cast-resin and VPI dry-type distribution transformers[J].Electric Power Systems Research,2019,172:105789.