Dry type Transformer - Specification 1

[NickParker]

Upon reviewing a transformer specification, it was noted that HV/LV dry-type transformers are required to have cast-resin HV windings and vacuum pressure impregnated (VPI) LV windings with an insulating Class F.

I wonder if the LV windings in cast resin transformers typically involve vacuum pressure impregnation (VPI), or are the LV windings also composed of cast resin? as I have not seen a cast resin dry type transformer physically.

 

[dpc]

Cast epoxy HV windings and VPI LV windings is pretty common for LV under 1000 V. Two different technologies. Cast coil windings are totally encapsulated in epoxy (probably done under vacuum) - basically impregnable. This is more expensive than VPI. I suspect googling will yield some photos.