Electrical Steel

Steels, which are characterised by their magnetic properties and used for manufacture of electrical Circuits. They are also called as Silicon Steel , Lamination Steel, Transformer Steel etc. They are supplied in the form of cold rolled sheet or strip generally less than 2 mm thick. Core Loss or Watt Loss plays a major role in identifying the application of the electrical steel as such. There are 3 Kinds of Electrical steel namely Amorphous, CRGO & CRNO.

Amorphous are suitable for wound electrical transformer cores.This material is a metallic glass prepared by pouring molten alloy onto a rotating cooled wheel, which cools the metal at a rate of about one megakelvin per second,so fast that crystals do not form. Amorphous steel is limited to foils of about 50 µm thickness. The mechanical properties of amorphous steel make stamping laminations for electric motors difficult. However Transformers with amorphous steel cores can have core losses of one-third that of conventional electrical steels.

Cold Rolled Grain Oriented Steel (CRGO) are suitable for Transformers. CRGO is mainly used in Power Transformers, Distribution Transformers and large rotating machines. Silicon content in this kind of steel ranges from 3 % to 6%. CRGO steels have preferential magnetic properties in Uni- direction of rolling (i.e ) they posse a well aligned crystal orientation to the rolling direction. Therefore, CRGO has superior properties like High Permeability, low magnetostriction and low core loss.

CRGO is further lassified in to 3 categories.

• Conventional Grades (M3,M4,M5,M6)
• HIB Grade (MOH)
• Domain Refined

Major Thickness in CRNO are 0.23, 0.27, 0.30 & 0.35 mm.0.20 mm are also seen in some HIB & Domain Refined CRGO grades.Core Loss are generally specified either at 50Hz or 60 hz and 1.7 T and Magnetic flux density values are specified at 800 A/m

Cold Rolled Non Oriented Steel (CRNO) are suitable for rotating machines like Motors, Generators as well as small transformers. Silicon content in this kind of steel ranges from 1 to 2.99 %. CRNO steels have similar magnetic with their grains running both transversely and in the rolling direction. Quality CRNO always depends on its superior properties like low core loss, high permeability, superior coatings suitable for welding with consistent thickness maintenance.

Major Thickness applied in CRNO are 0.35, 0.50 & 0.65 mm.Unless otherwise specified, generally each grade will have its core loss value 50Hz and at 1.5T Different grades are 210,230,250,270,300,360,400,440,470,600,700,800,1000,1300,1600.

Insulation Coating Types

• Organic Coating (C3) generally has varnish which withstand around 180 deg Celsius
• Semi Organic Coating (C6) is a combination of both organic and in organic coating and considered to be best suitable for Welding.