The main insulating material in a cast resin transformer is the epoxy resin, which holds together the complex network formed by the HV coil.
Research has shown that the initial partial discharge level of a cast coil transformer is a crucial determinant of how long will this transformer serve. The latest IEC standards impose initial level lower then 10 pC.
We at SETF pride ourselves with transformers that attained partial discharge level of less then 1.5 pC after being subjected to the harshest dielectric tests and this is certified by third party independent laboratories.
Another characteristic of a cast resin transformer is its inherent characteristic to withstand dynamic short circuits. We also pride ourselves with transformers that can withstand up to 3 seconds of symmetrical dynamic short circuits.
Once the two above characteristics combined in one electrical transformer, sound levels will become a very trivial issue and once again the superior workmanship and design of SETF cast-coils transformers have resulted in sound level that are on average 25 to 40 % better then those stipulated by IEC.
All of those performances are guaranteed by independent certificates.