How Does CRGO STEEL Reduces Core Loss in Transformers

CRGO (Cold-rolled grain-oriented sheet steel) is used for reducing the core losses in transformers.
Each type of steel has "grains" which consist of "domains". These "domains" are nothing but electrical charges oriented in any random direction.

Core loss= Hysteresis + Eddy Current Loss

In CRGO steel, core loss along the grain is significantly less as compared to core loss across the grain. This is an important property of CRGO steel.

In the case of power transformers, the core is built up of CRGO steel in such a way (i.e. by using mitered joints) that flux is always oriented along the grains. Therefore, a considerable reduction in core loss is achieved.

However, this property of CRGO steel cannot be utilized in rotating machines because, in the case of rotating machines, it is not possible to construct the core in such a way that flux is always oriented along the grains. This is because, in rotating machines, the direction of flux in the tooth is perpendicular to the direction of flux in the circumference.

Reduction of hysteresis loss:
(1) The size of the "grains" in CRGO steel are purposely "grown" & made bigger & are about 10 times the size of the grains in regular steel.
(2) The grains in CRGO steels are all aligned almost parallel to the direction of rolling of the steel (i.e. the length of the steel).

Reduction of eddy current loss:
A special car-lite insulation coating on the steel is being done to reduce the eddy current loss.

thus, CRGO steel reduces core loss in transformers