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Quality Standard

Raw Material Quality Check

The quality of final output depends upon quality of input. At Vilas Transcore, we undertake significant and relevant quality check of raw material. The raw material is brought in for the manufacturing process only if it successfully passes through all the rigorous Quality Tests.


Lamination Quality Check

Lamination Quality control checks are carried out frequently right through the manufacturing process on every machine and the record is maintained separately.

This covers checking of Edge, Width, Burr, Camber, Thickness, Watt Losses, Stack factor, wave factor etc...


Toroidal Cores / Wound Cores Quality Check

Quality Check includes Magnetic Properties on given flux density and dimensional measurement i.e. Overall – Inside Dia Meter & Height.


Technical details of c.r.g.o.

c.r.g.o. or Cold Rolled Grain Oriented Steel is available in various grades (generally called M3, M4, M5 & M6, Major international standards such as Japanese (JIS), American (ASTM), German (DIN) and British Standards which specify c.r.g.o. grade).

Conventional c.r.g.o. grades generally M3, M4, M5, and M6 are used regularly for Lamination cores in Transformers. However recently due to environmental protection, energy savings are becoming a must. Nippon Steel Corporation and other c.r.g.o. producing mills has come out with low loss Hi-B materials, which guarantee low Watt Losses at 1.7 Tesla flux density. Such materials are called Hi-B materials.

Below given table indicates magnetic properties of Hi-B material.

Popular c.r.g.o. Hi-B grades are 23 MOH & 27 MOH ZDKH, ZDMH/HPDR.

Manufacturing mills of c.r.g.o. Steel guarantee the core loss figure at flue density of 1.5 Tesla in case of c.r.g.o. conventional grain oriented steel and at 1.7 Tesla in case of c.r.g.o. Hi-B Steel and c.r.g.o. Hi-B-LS Steel.


Flux Density V/s Losses

These results were measured in Vilas Transcore Limited Testing Laboratory
These values are for reference only. All values are in Watts/kg @ 50 Hz

Flux Density (Tesla) 23PHD85 27ZDKH90 27ZDKH95 23 MOH 27 MOH 30 MOH M3 M4 M5 M6
1.30 0.46 0.51 0.48 0.53 0.57 0.57 0.49 0.64 0.68 0.73
1.350.490.550.510.570.600.620.530.680.740.79
1.400.530.590.570.610.660.650.580.740.800.86
1.450.570.630.610.660.700.700.640.780.870.94
1.460.580.640.620.670.710.710.650.800.880.97
1.480.600.660.640.660.730.740.670.820.911.03
1.500.610.670.660.700.740.760.700.840.941.11
1.520.630.690.680.720.760.780.720.880.971.14
1.540.650.710.700.740.790.800.750.901.011.18
1.560.670.730.720.760.810.830.780.931.041.22
1.580.690.750.740.780.830.850.810.961.081.26
1.600.710.770.760.800.850.870.851.001.121.30
1.620.730.790.790.830.890.900.891.031.161.35
1.640.750.810.830.850.910.930.931.071.201.40
1.660.780.840.870.880.940.960.981.101.251.45
1.680.810.870.910.930.961.001.031.151.301.51
1.700.840.900.950.951.001.051.091.201.361.57
1.720.860.931.010.981.021.071.151.241.421.64

Important physical properties of c.r.g.o.

Density gm/c3 7.65
Silicon content% 3.10
Resistivity micro Ohm-centimeter 48.00
Ultimate tensile Strength 00 to Rolling Direction Kg/mm2 32.60
Ultimate tensile Strength 900 to Rolling Direction Kg/mm2 38.20
Stacking factor % M4 (.27mm) 96.00
Stacking factor % M5 (.30mm) 96.50
Stacking factor % M6 (.35mm) 97.00
CRGO materials come either in the form of coils or sheets. Given below the details of CRGO dimensions and tolerances as per JIS C 3553.

Standard Tolerance - Cut to Size Lamiantion

Sr No Characteristics Accaptance Limit / Criteria
1 Width (mm) 0 to 100 (± 0.15)
100 to 130 (± 0.20)
230 to 380 (± 0.25)
380 to 580 (± 0.40)
580 to Above (± 0.50)
2 Thickness (mm) ± 0.03 mm
3 Edge Burrs (Micron)  
Thickness (mm)  
Up to 0.23 15
0.27 to 0.30 15
0.35 20
4 Length (mm) Up to 350 (+0.00 / -0.30)
350 to 1000 (+0.00 / -0.60)
1000 to 2000 (+0.00 / -1.00)
2000 and Above (+0.00 / -2.00)
5 Edge Chamber For the material with a width greater than 150 mm,
edge chamber shall not exceed 0.8 mm for a length 1.5 meter
6 Wave Factor
(i.e. Deviation from Flatness)
For a material of width greater than
150 mm the deviation from flatness expressed as a percentage
shall not exceed 1.5%
7 Angle ± 5 Minutesw
8 Stack Thickness of individual
stack except centre step unclamped
+1 -0 mm

Testing Parameter for Toroidal Core

Reluctance - Toroidal Core
Grade of Material AT 0.5 Tesla AT/CM AT 1.0 Tesla AT/CM AT 1.5 Tesla AT/CM AT 1.7 Tesla AT/CM
0.23 ZDMH/HPDR 0.06 0.10 0.20 0.30
0.23 ZdKH 0.07 0.12 0.22 0.32
0.23 MoH 0.08 0.15 0.26 0.35
0.23 M3 0.09 0.18 0.30 0.45
M4 0.12 0.22 0.32 -
M5 0.15 0.28 0.40 -