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TECHNICAL DETAILS :
CRGO 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 are given in table 1 which specify grade, thickness, Watt Losses and Magnetic Flux density.
IMPORTANT ELECTRICAL PROPERTIES OF CRGO
Table 1 - Grain Oriented Electrical Steel strips
| Japanese |
| JIS C 2553 (1986)
|
| Classification
|
Density
(kg/dm) |
Iron
Loss
(W/kg)
W17/50 |
Magnetic
Flux
Density (T) B |
| Symbol |
Thickness
mm
|
| 27
P 100 |
0.27 |
7.65 |
1.00 max. |
1.85 |
| 27
P 100 |
1.00 max. |
| 27
G 120 |
1.20 max. |
1.78 |
| 27
G 130 |
1.30 max. |
| 27
G 140 |
1.40 max. |
1.75 |
| 30
P 110 |
0.30 |
1.10 max. |
1.85 |
| 30
P 120 |
1.20 max. |
| 30
G 130 |
1.30 max. |
1.78 |
| 30
G 140 |
1.40 max. |
| 30
G 150 |
1.50 max. |
1.75 |
| 35
P 125 |
0.35 |
1.25 max. |
1.85 |
| 35
P 135 |
1.35 max. |
| 35
G 145 |
1.45 max. |
1.78 |
| 35
G 155 |
1.55 max. |
| 35
G 165 |
1.655 max. |
1.75 |
| British |
| BS 601 Part 2 (1973)
|
| Maximum specific total loss at a
peak magnetic flux density of 1.5T and a frequency
of 50 Hz. |
Grade
|
Maximum specific total loss W/kg
|
35M6
|
1.11 |
30M6
|
1.07 |
30M5
|
0.97 |
28M5
|
0.95 |
28M4
|
0.89 |
| |
|
| USA |
| AISI ( 1983 )
|
| MAXIMUM CORE LOSSES - Electrical
Steels Grain Oriented Full Processed ASTM A665
|
ASTM
Type
|
Former
AISI
Type
|
Thickness
|
Maximum Core Loss at 15 kg (1.5 T)
|
| W /
lb |
W /kg
|
Inch
|
mm |
60Hz
|
50Hz
|
60Hz
|
50Hz |
27G053
|
M-4 |
0.0106
|
0.27 |
0.53 |
0.40 |
1.17 |
0.89 |
30G058
|
M-5 |
0.0118 |
0.30 |
0.58 |
0.44 |
1.28 |
0.97 |
35G066
|
M-6 |
0.0138 |
0.35 |
0.66
|
0.50 |
1.46 |
1.11 |
IMPORTANT PHYSICAL PROPERTIES OF
CRGO
Density gm/c3
|
7.65 |
Silicon content %
|
3.10 |
Resistivity micro
Ohm-centimeter
|
48.00 |
Ultimate Tensile Strength 0° to
Rolling Direction Kg/mm2
|
32.60 |
Ultimate Tensile Strength 90° to
Rolling Direction Kg/mm2
|
38.20 |
| Stacking factor % M4 (.27
mm) |
96.00 |
| Stacking factor % M5 (.30
mm) |
96.50 |
| Stacking factor % M6 (.35
mm) |
97.00 |
| CRGO materials come either in the
form of coils or sheets. Table 2 gives details of
dimensions and tolerances as per JIS C
3553. | DIMENSIONS &
TOLERANCES
| COILS |
Thickness |
0.18 mm (0.0071 in.
) |
| 0.20 mm (0.0079 in.), 0.23 mm
(0.0091 in. ) |
| 0.27 mm (0.0106 in.), 0.30 mm
(0.0118 in. ) |
| 0.35 mm (0.0138 in.) |
Width
(Standard
width available with range)
|
914 mm (36 in.), and 1000 mm (39 in.
) |
| from 50 mm(2 in.), to 1.050mm (41
in. ) |
Inside Coil Diameter
|
508 mm (20 in. ) |
| Sheets |
Thickness |
0.30 mm (0.0118 in.), 0.35 mm
(0.0138 in. ) |
| Width |
914 mm (36 in.), and 1000 mm (39 in.
) |
| Length |
Length will be available according
to negotiation |
Tolerances in Dimensions & Shape -
conform to JIS C 2553.
Width
mm
|
Thickness mm |
TOLERANCE |
| Thickness mm |
Deviation of thickness
in transverse direction
mm
|
Width
mm
|
Camber in any 2 metres
(Slit
Products)
mm
|
Shear Burr mm
|
150
or
under |
0.18
0.20
0.23
0.27
0.30
0.35
|
+0.02
+0.02
+0.02
+0.03
+0.03
+0.03
|
0.02 or under
|
+0.20 |
1.0 or
under |
0.05
or
unde
|
over 150
to 400 |
0.18
0.20
0.23
0.27
0.30
0.35
|
+0.02
+0.02
+0.02
+0.03
+0.03
+0.03
|
0.02
or under
|
+0.30 |
over 400
to 750
|
0.18
0.20
0.23
0.27
0.30
0.35
|
+0.02
+0.02
+0.02
+0.03
+0.03
+0.03
|
0.03
or under
|
+0.50 |
| over 750 |
0.18
0.20
0.23
0.27
0.30
0.35
|
+0.02
+0.02
+0.02
+0.03
+0.03
+0.03
|
0.03
or under
|
+0.6
0 |
Besides the Watt Losses at specific flux densities of 1.5 T and 1.7 T CRGO manufacturers also give curves of indicating Watt Losses ad A.C. Magnetization at various flux densities. These curves are of immense help to Transformer designers, and available on request.
Conventional CRGO materials (M4, M5, M6) are used regularly for cores in Transformers. However recently due to environmental protection, energy savings are becoming a very important factor and minimizing care loss in Transformers is becoming a must. Nippon Steel Corporation has come out with low loss Hi-B materials, which guarantee low Watt Losses at 1.5 Tesla flux density. Such materials are called Hi-B materials. Table 3 gives magnetic properties of Hi-B material. Popular Hi-B grades used in India are 23 MOH &
27 MOH Watt.
Hi - B CRGO MATERIALS
:
Thickness
|
Grade |
Core Loss
|
Lamination
Factor |
Max.
|
Typical
|
Typical
|
Typical |
| mm |
mil |
W
(W/Kg) |
W
(W/Kg) |
W
(W/Kg) |
W
(W/Kg) |
W
(W/Kg)
|
B
(T)
|
% |
| 0.23 |
9 |
23ZDKH85 |
0.85
|
0.57
|
0.78
|
0.34
|
0.46
|
1.91
|
97.5 |
| 23ZDKH90 |
0.90
|
0.58
|
0.80
|
0.35
|
0.48
|
1.91 |
| 23ZDMH85 |
0.85
|
0.57
|
0.78
|
0.34
|
0.46
|
1.91 |
97.4 |
| 23ZDMH90 |
0.90
|
0.59
|
0.81
|
0.35
|
0.48
|
1.91 |
| 23ZH90 |
0.90
|
0.63
|
0.87
|
0.37
|
0.51
|
1.92
|
97.7 |
| 23ZH95 |
0.95
|
0.64
|
0.90
|
0.38
|
0.53
|
1.92 |
| 23M-OH |
1.00
|
0.66
|
0.93
|
0.39
|
0.54
|
1.92 |
| 0.27 |
11 |
27ZDKH90 |
0.90
|
0.62
|
0.84 |
0.38
|
0.53
|
1.92 |
98.0 |
| 27ZDKH95 |
0.95
|
0.65
|
0.88
|
0.39
|
0.52
|
1.91 |
| 27ZDMH90 |
0.90
|
0.62
|
0.84
|
0.38
|
0.53
|
1.91
|
97.9 |
| 27ZDMH95 |
0.95
|
0.65
|
0.88
|
0.39
|
0.53
|
1.91 |
| 27ZH95 |
0.95
|
0.69
|
0.93
|
0.41
|
0.55
|
1.91 |
98.1 |
| 27M-OH |
1.03
|
0.72
|
0.99
|
0.43
|
0.59
|
1.91 |
| 27M-1H |
1.09
|
0.74
|
1.03
|
0.44
|
0.61
|
1.91 |
| 0.30 |
12 |
30ZH100 |
1.00
|
0.73
|
0.98
|
0.44
|
0.58
|
1.92
|
98.3 |
| 30M-OH |
1.05
|
0.74
|
1.01
|
0.44
|
0.60
|
1.91 |
| 0.35 |
11 |
35M-1H |
1.16
|
0.85
|
1.13
|
0.52
|
0.68
|
1.92 |
98.5 |
| 35M-2H |
1.22
|
0.90
|
1.19
|
0.54
|
0.73
|
1.92 |
A. K. Steel Corp. of USA ( formally
ARMCO) has also come out with their own brand of
low loss CRGO called Trancor H-0 and Trancor H-1.
The Watt Losses are as follows :
CORE
LOSSES
ARMCO TRAN. CORE
|
THICKNESS INCHES (mm) |
WATTS PER KG 60 Hz 1.7 T
|
WATTS PER KG 50 Hz
1.7
T |
| H-0 |
.009 ( .23 ) |
1.32 |
1.01 |
| H-1
|
.011 ( .27 ) |
1.46 |
1.11 |
|
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