Core Assembly - AMM POWER Pvt Ltd.

The Core Coil Assembly is the heart of a transformer, responsible for transferring electrical energy from one circuit to another through electromagnetic induction. It consists of two main parts:

Core: A magnetic structure made of laminated silicon steel that provides a path for the magnetic flux.
Coil (Windings): Conductive wire (copper or aluminum) wound around the core to carry the electrical current.

Function of Core Coil Assembly

Converts electrical energy from one voltage level to another.

Reduces energy losses by minimizing heat and magnetic resistance.

Ensures efficient power transmission with proper insulation and cooling.

Components of Core Coil Assembly

Core:
- Made of thin silicon steel laminations to reduce energy losses.
- Provides a low-resistance path for the magnetic field.
Windings (Coils):
- Primary Winding: Receives electrical energy from the source.
- Secondary Winding: Delivers the transformed voltage to the load.
- Insulated with materials like paper, resin, or oil to prevent short circuits.

Process of Core Coil Assembly

Core Preparation: Steel laminations are stacked and insulated.

Winding Fabrication: Copper or aluminum wires are wound around the core.

Insulation & Assembly: Windings are insulated and fixed to the core.

Vacuum Drying & Impregnation: Removes moisture and enhances insulation strength.

Final Assembly: Components are clamped together and prepared for enclosure.

Importance of Core Coil Assembly

Ensures smooth and efficient power transmission.

Reduces energy losses and enhances transformer life.

Provides electrical insulation and mechanical strength.

Technical Specifications

Characteristics of CRGO electrical steel are affected by impurities, grain size, grain orientation and surface insulation. Even minor stresses, burrs, edge cambers or bends can increase core losses and magnetizing current significantly. Jay Bee Laminations Limited has the facilities to ensure proper handling and stress free processing of the material.

General physical and mechanical properties of CRGO steel
Density	7.65 g/cm3
Thickness of sheet	0.23 – 0.35 mm
Silicon content	3-4 %
Yield Point (relative to rolling direction)	0 degrees • 330 N/mm2 90 degrees • 355 N/mm2
Tensile strength	0 degrees • 348 N/mm2 90 degrees • 412 N/mm2
Elongation	0 degrees • 11% 90 degrees • 31%
Number of bends	0 degrees • 21 90 degrees • 15
Hardness (Hv)	204
Stacking factor	95-98%

Grade classification of Electrical Steel

Electrical Steel	Grade (BIS nomenclature)	Grade (Conventional nomenclature)	Thickness (mm)	Max Core loss (W/kg) 50 Hz
Electrical Steel	Grade (BIS nomenclature)	Grade (Conventional nomenclature)	Thickness (mm)	@1.5T	@1.7T
CRGO	20HP70D	20-70	0.20	0.52	0.70
	23HP75D	23-75	0.23	0.55	0.75
	23HP85D	23ZDKH	0.23	0.60	0.85
	23HP90	23M0-H	0.23	0.64	0.90
	23HP100	M3 (Low loss)	0.23	0.68	1.00
	23CG110	M3	0.23	0.70	1.10
	27HP90D	27ZDKH	0.27	0.66	0.90
	27HP100	27M0-H	0.27	0.70	1.00
	27HP110	M4 (Low loss)	0.27	0.78	1.10
	27CG120	M4	0.27	0.85	1.20
	30CG130	M5	0.30	0.90	1.30
CRNGO	35C230		0.35	2.30
	50C470		0.50	4.70
	50C600		0.50	6.00

Tolerance chart for dimensions of CRGO laminations (as per IS 3024)

Attribute	Attribute Range/Value	Tolerance
Width	0 – 100 mm 100 mm – 230 mm 230 mm – 400 mm 400 mm – 750 mm	+0.00 / -0.15 mm +0.00 / -0.20 mm +0.00 / -0.30 mm +0.00 / -0.50 mm
Length	0 – 350 mm 350 mm – 1,000 mm 1,000 mm – 2,000 mm 2,000 mm – 3,000 mm 3,000 mm – 4,000 mm	+0.00 / -0.30 mm +0.00 / -0.60 mm +0.00 / -1.00 mm +0.00 / -1.50 mm +0.00 / -2.00 mm
Thickness	0.23 – 0.27 mm 0.30 – 0.35 mm	+/- 0.025 mm +/- 0.030 mm
Mitering Angle	45 degrees	+/- 5 minutes
Burr Height	0.18 – 0.23 mm 0.23 – 0.30 mm 0.30 – 0.35 mm	10 microns 15 microns 20 microns
Wave Factor	Material width > 150mm, Flatness deviation	Max. 1.5% of width
Edge Camber	Material width > 150mm	Max. 0.8 mm for length of 1.5m
Hole Dimension	Up to 34 mm	+/- 0.15 mm