Siemens Vacuum Pressure Impregnated (VPI) Medium Voltage Transformers
VPI transformer coils are vacuum pressure impregnated in high temperature polyester varnish. The process includes complete submersion in varnish under vacuum and pressure and regulated curing using statistically process controlled equipment to ensure consistency. The finished coils are effectively protected against moisture, dirt, and most industrial contaminants. VPI transformers are generally suitable for use indoors or outdoors where people work and breathe. A 220˚C Class UL Listed insulation system is used on all VPI transformers regardless of specified temperature rating.