That is the catchphrase when discussing transformers. But what does it realy mean?
Hypersil, a phrase coined at Westinghouse, simply means “grain-oriented Silicon Steel”. The most typical and commonly seen form of this is a “cut core”. The cores are made from silicon strip steel that is “wound” into an oblong, semi-rectangular shape. Winding the strip steel in this fashion keeps the “grain” of the steel all going in the same direction. The cores are then “cut” and the cut surfaces are highly polished so that they can be matched up again after being placed around the coil. The cores must then be tightly banded to minimize (as much as possible) the “hum” often heard from transformers. This “hum” is caused by the 2 smooth surfaces “vibrating” when power is run through the unit and is extremely difficult to prevent, even with banding and varnishing. In addition, the entire process of manufacturing this type of core is both labor intensive and expensive.
Solution: Distributed Gap (DG) Cores.
These are also grain-oriented Silicon Steel, but they are NOT wound and cut. They are machined to have steps or gaps that allow the cores to be “woven” back together . This prevents the smooth surface that allows for vibration. These units are easier to work with, more economical and, above all, QUIET, which is what our transformers should be.