ELECTRICAL STEEL : Electrical Steel, also called lamination steel, silicon electrical steel, silicon steel or transformer steel is speciality steel tailored to produce certain magnetic poperties, such as small hysteresis area (small energy dissipation per cycle, or low core loss) and high permeability.
1) Hot Rolled Coil-> Pre-Annealing and Pickling -> High Temperature Annealing -> Insulation Coating -> PH-Core & PG-Core
1) CRGO: Core laminations are the main part of an electrical transformer, and this attribute to 70% of a transformer cost. These core laminations are required to be cut from special steel called as Cold Rolled Grain Oriented Electrical Steel or popularly known as CRGO. The CRGO is a special quality of steel which have a special grain surface and comes in a thickness of 0.23 mm, 0.27 mm, 0.30 mm, 0.35 mm. (generally called M3, M4, M5 & M6). Lower the thickness of material better is the quality of material.
The Quality of CRGO is measured in terms of lower losses of electrical current, which flow in the core. The proper design of core and good quality of core material do a best job in combination. Mainly the core losses are measured in Watts per Kg.
Every type of steel has "grains" which consist of "domains". These "domains" are nothing but electrical charges oriented in any random direction. Therefore if a transformer were to be made of Mild Steel used as core material, the core loss would be approx. 16 to 17 w/kg at 1.5T/50Hz and the size of the transformer would be approx. 18 to 20 times the size of a transformer manufactured with GO steels.
A table indicating core losses of some popular grades of CRGO is as under:-
Core Losses (w/Kg) 1.7T/50Hz
A) PG Core: The grain's easy magnetization direction is aligned to the rolling direction. Therefore, this product features excellent magnetic properties in the rolling direction. It is widely used for large-sized power transformers or large or small size transformers.
Inner Coil Diameter
Available Width Range
508-520 (Standard: 508)
2) CRNGO (Non-Oriented Electrical Steel): CRNGO steel usaully has a silicon level of 2 to 3.5% and have similar magnetic properties in all directions in plan of the sheet. Non-oriented Electrical steel are principally used for motors, generators, alternators, ballasts, small Transformers and a variety of other electromagnetic applications.
Specific Cores Loss W/Kg. At.
1.0 T 50Hz
1.5 T 50 Hz
At 5000 AT/m(T)
A) PN-Core: The non-oriented electrical steel features even magnetic properties in the rolling direction and in other directions. They are widely used for iron core materials of rotating machines ranging from large-size power generators to small-size precision electric motors. They are also desirable for iron core of small-size power transformers.
Inner Coil Diameter
35PN210, 35PN230, 35PN250, 35PN270
35PN300, 35PN360, 35PN440
509N250, 509N270, 509N290, 509N310,
509N350, 509N400, 509N470
65PN290, 65PN310, 65PN350, 65PN400,
50PN600, 50PN700, 50PN800, 50PN1000, 50PN1300
1000, 1100, & 1200
65PN600, 65PN700, 65PN800, 65PN1000, 65PN1300,
B) PNM Core: It is utilized as steel material for magnetic switches and improved in wear resistance and residual magnetism.
1000, 1050, 1100
Click here for Major International Standards for Electrical Steel