COMPANY PROFILE

"Vikarsh Stampings India Pvt. Ltd." is amongst the leading manufacturers, exporters and suppliers of high quality and performance grain-oriented transformer lamination cores in conventional and HI-B grades. Our range include Mitered Transformer laminations for distribution and power transformers up to 75 MVA. rectangular strips, Assembled Core Frame Assemblies upto 5 MVA, P.T. Cores, Toroidal Cores, C.T. Cores, Loco Lamination Cores, Step Lap Cores available in both vertical and horizontal and also a combination of both.

Our company was established in the year 2000 at Pune (Maharashtra). Over the years the company has achieved considerable growth in output and customer base. As business grew, working from different locations became logistically difficult and therefore the company shifted to Dhangarwadi near Shirwal (about 50 kms from Pune) adjoining Pune-Bangalore highway, which became an ideal and strategic location for production and dispatch of its products. This set-up covers a vast area of about 2,88,000 sq. ft. with an existing double bay shed of 55,000 sq.ft.

The business operations of our company are being handled by three young directors: Mr. Milind Wani, Mr. Sameer Shinde and Mr. Laxmikant Trivedi well supported by their Technical Director, Mr. Stanley D'Costa. Mr. Stanly has more than 40 years of experience and vast knowledge in this field. His experienced approach as well as in-depth knowledge of the involved processes guides us in meeting the customer specification of all our products, and other associated product requirements of the clients.

Vikarsh Stampings India Pvt. Ltd. has made a firm consolidation in its business through meticulous planning and continual improvement in quality of its products to fully meet customer's requirements. Today, our consistency in meeting the emerging demands of the transformer industry has assisted us in making many reputed clients in the domestic market. Further, our production expertise allows us to deliver the range according to the client's specification and has also aided us in strengthening our position in the market.

Products We OfferOur product portfolio includes the following:

Mitered Transformer Lamination up to 75 MVA Rectangular Strips and assemblies

Core Frame Assemblies up to 5 MVA

Slit Coils

Toroidal Cores upto 400 kV CT cores with max O.D. of 740 mm.

About Our FacilityCapacity:

7,500 MT Per Annum in existing sheds of 55,000 Sq. Feet

Brief Description Of Machinery: CNC CUT to length Automatic core cutting line with step lap and tip cutting

facility up to 640 mm. width and 4250 mm. length 3 Nos. slitting machines including 2 imported Weybridge slitting machines.

5T, 10T and 15T double girder EOT cranes. 1 No mobile crane

Power presses up to 63 MT capacity. Total 10 nos.

Special purpose multi holing press with Uni punch holing systems.

Power shears, treadle shearing machines from 2 feet width to 13 feet width

PID controlled Roller Hearth Annealing Furnace for continuous stress relief annealing of CRGO laminations.

Forklifts. pallet trucks for material handling

Special purpose inert gas batch annealing furnaces with PID controls, N2 cylinder bank and manifold with controlled annealing for toroidal cores

Grinding machines for sharpening of blades

Tool & cutter grinding machines for grinding slitting cutters

Surface grimier for grinding V nothing tools, holing dies, punches, etc.

Test Equipment: Calibrated Scales, Verniers Micrometers. Digital Micrometer.

Dial gauges with 1 micron least count.

Single sheet core loss Tester.

Epstein square tester as per IS 649.

Test Bench for testing of all types of toroidal cores upto 100 kgs weight of single sore.

Complete dummy turns tester for testing No Load Losses of assembled transformer core up to 5 MVA with 50 amps power source and Yokogawa Power Analyzer.

PRODUCTS

Mitred Transformer Lamination

Step LapToroidal Cores (Ring

Cores)

Core Frame AssembliesRectangular Strips in CRGO/

CRNOSlit Coil

Mitred Transformer LaminationOur in-depth process knowledge as well as modern production facilities allow us to successfully meet the demands of mitred transformer lamination. The technical expertise of our team allows us to manufacture these for a wide range of transformers ranging from 25 KVA to 75 MVA 'V' nothing and multi-holing as per customer requirements.

Standards Followed

Burr Level Max 0.022 mm.

Width Cutting Tolerance

+/-0.3 mm

Length Cutting Tolerance

+/-0.3 mm

LossesAs certified by the mill Guarantee

Stacking factor (%)

95 Min.

FlatnessWave height to length Ratio:- 1.5 Max.

DuctilityMinimum Number of bends :- > = 3

Specifications

Ranging from 25 KVA to 10000 KVAAvailable with 'V' Notching

Available with Holing Facilities

Salient Features Distribution and power transformer laminations in upto

75 MVA.Step Lap laminations with Tip Cutting(both horizontal &

vertical step lap)to give reduced losses.

Stress relief annealed laminations to give lower losses and lower current values.

Mitred Transformer Lamination

Step Lap

Few days back mitred "stacked core" designs superseded cores which used rectangular joints. The development of mitred corner joints and in particular yokes with "V" notches to locate the centre leg allowed less core steel to be used, thus reducing the cost of transformer. Typically with overlap designs sheets are laid in pairs (2 by 2 or 3 by 3). The choice is to make a balance between faster core building and the overall efficiency of the core.

There has been a constant drive to reduce material and manufacturing costs in the design of distribution transformers. When considering the various material in a transformer of paramount importance is the overall cost of the core steel used. This cost is influence by a number of factors, namely the loss factor of the silicon steel, the weight required (affected by the loss factor of the silicon steel) and the design of the core. There are many permutations which can be played between the raw cost of silicon steel, its loss factor, the amount required in a core and hence the material cost of the core.

About 30 years ago Westinghouse, in its research to reduce costs, invented a novel system of cross step-lap. In this design the overlap at the joints is much less than traditional overlap (3 - 5 mm compared to 10 -15 mm} but the shift progresses for 5 to 7 sheets before starting again. A key part of the Westinghouse design is the centre-leg where the notch in the yoke is progressively moved across the yoke according to the number of steps (the centre-leg length

remains the same). There are three principle benefits of Westinghouse step-lap, firstly reduced material costs, as less core steel is required for the same losses, secondly faster assembly of the core and thirdly lower noise.

The building factor used with cores manufactured like this will be between 1.10 and 1.14. whereas hand cut cores will typically use building factors of between 1.25 and 1.30.

This means there is the potential to make a material saving of up to 20%

Winding on-the-leg allows even more material savings as the windings are that much closer to the core less copper (or aluminium) can be used.

NOISE REDUCTIONAn important benefit of step-lap cores is-they exhibit lower noise compared to overlap cores. This can be particularly important as there is increasing requirement to reduces the noise of transformers.

Toroidal Cores (Ring Cores)

Toroidal cores and ring cores offered by us have find usage in mains transformers and are wound from cold rolled grain oriented (CRGO) silicon steel strips to provide optimum performance. These toroidal cores and ring cores are wound by automatic core winding machine and are annealed in high vacuum furnace under protection atmosphere or in continuous tunnel furnace, which results in features like compact volume, light, low magnetic leakage and hum & high efficiency.

SpecificationsSizes upto 700 mm ODIn CRGO grades required by customer, duly wound and annealed in inert atmosphereGuaranteed No load current (AT /Cm) as per B-H Curve of particular gradeIn house testing facilities and 100% testing done on all Toroidal Cores at flux densities specified by customers.

Core Frame Assemblies

We offer clients high performance transformer cores, core frames, oriented core frame assemblies that find application in meeting the specific application demands of industrial and commercial transformers. These core frame assemblies are also duly assembled and tested for no load losses with dummy turns, which assure clients of their flawless and consistent performance.

We have with us cutting-edge technical expertise to meet the specific manufacturing demands of core frame assemblies. These are offered for a wide range of transformers starting from 25 KVA to 5 MVA. Further, the high quality standards followed during the production stage also ensure optimum service life standards for core frame assemblies.

Specifications: Miltered Lamination core frame assemblies upto 5 MVA with facilities to test no load losses off power analysis of our works.

Rectangular Strips in CRGO/ CRNOWe offer clients rectangular strips in CRNO/CRGO that are offered in both loose conditions or can also be assembled as per client's specifications. Our modern production facilities also help us to deliver these rectangular strips in different specifications which can differ on the basis of width, lengths, raw material used and others.

The rectangular strips we offer are available in different specifications/finishes as per their specific application requirements in transformers. Our process expertise also allow us to deliver these rectangular strips in special type of HI-B grade material in loose conditions or assembled to customers requirements.

Specifications (Round Cores):

Width 20 - 600 mm

Length 20 - 3000 mm

Special Type of E & I

As per the client's design

Raw Material Available

Special Type of HI-B Grades material is also available. Details for same will be provided on request

Grade Thickness Watts /Kg.

M/3 0.23 mm 0.85 watts /kg

M/4 0.27 mm 0.90 watts /kg

M/5 0.30 mm 1.02 watts /kg

Available in both in loose condition or assembled to customer's requirements

Slit CoilWe offer clients high quality slit coil used in transformers. These slit coil are duly annealed and tested up to 420 Kv class cores in instrument transformers to ensure optimum performance and service life standards.

Our slit coils can be availed in different sizes, shapes and thickness based upon the demand of the application.

As per requirements of customer in width from 15 mm onwards in multiples of 5 mm. I.D. of slit coils 508 mm dia. (20") to fit into standard decoilers of CNC and unicore machines.

Quality Standards

TOLERANCE CHART FOR CRGO LAMINATIONS

ATTRIBUTE

ACCEPTANCE LIMITS

THICKNESS +/- 0.02mm. Total difference in thickness in a direction perpendicular to rolling direction should not exceed 0.02mm.

LENGTH Upto 700mm + 0.0/ - 0.5mm

701 to 2000mm + 0.0 / -1.0mm

Over 2000 mm + 0.0 / - 1.5 mm

WIDTH Upto 150 mm +/- 0.1 mm

151 to 500 mm +/- 0.2 mm

501 mm and above +/- 0.3 mm

CAMBER 1.0 mm max. on 2000mm length

V NOTCH 90 deg +/- 5 minutes

MITRED ANGLE 45 deg +/- 5 minutes

HOLE DIAMETER + 0.10 / - 00mm

STACKING FACTOR 95.0% min. for 0.23mm thick material

96% min. for 0.27mm and 0.30mm thick material

97% min. for 0.35mm thick material

INSULATION RESISTANCE Min. 10 Ohms/cm2 as per Franklin method described in IS 649-1996

BURR 25 microns maximum

WEIGHT OF EACH STEP + 0.5% to 1.0% or as per customer's requirements.

WATT LOSS M3 Grade: Max .77 watts/kg at 1.5T and 50Hz

M4 Grade: Max 0.89 watts/kg at 1.5T and 50Hz

M5 Grade : Max 0.97 watts/kg at 1.5T and 50 Hz.

M6 Grade: Max 1.1 watts/kg at 1.5T and 50 Hz

Watt loss is also specified as below.

A B C

A Denotes metal thickness (100 times actual thickness of material; in mm)

B Denotes alphabetal code. In IS 3024. It is CG for conventional grade and HP for high permeability grade.

C Denotes guaranteed watt loss (number denotes 100 times the watt loss at flux density of 1.7 Tesla and a frequency of 50Hz)

Example : 27CG 130 means that thickness is 0.27mm, that it is conventional grade CRGO and it has a maximum watt loss of 1.30

watts/kg at 1.7T and 50Hz.

TOLERANCE CHART FOR TOROIDAL CORES

ATTRIBUTES ACCEPTABLE LIMITS

OUTSIDE DIAMETER

OVER UPTO TOLERANCE IN MM

40100 300

100300-

+/- 1.0+/- 1.30+/- 2.0

INSIDE DIAMETER - 0.0MM/+1MM

WIDTH/HEIGHTUPTO 200MM OD : '-0.0/ + 1 MM OVER 200 MM OD : '-0.0/+1.5 MM

SLIT BURR 25 microns

WEIGHT -0.0 /+0.2 % of nominal weight

MAGNETICCHARACTERISTICS

Grade M3 0.29AT/CM at 1.5T/50HzM4 0.31 AT/CM at 1.5T/50HzM5 0.35 AT/CM at 1.5T/50Hz M6 0.40 AT/CM at 1.5T/50Hz

NOTE: (a) For high Permeability Grades (HiB grades) the magnetizing force is guaranteed in terms of AT/cm at 1.7T/50Hz depending on grades. (b) Magnetizing force is specified at 1.5T only, but we can test at 2 or more flux densities depending on customer's requirements.

CRGO RAW MATERIALSGiven below are major international standards for CRGO materials which so far has been the main guide-line

for lamination and transformer manufacturers.

MAJOR INTERNATIONAL STANDARDS

GRAIN-ORIENTED ELECTRICAL STEEL STRIP

JAPANESE

JIS C 2553 (1986)

Classification Density (kg/dm3)

Iron Loss (w/kg) W 17/50

Magnetic Flux density (T)B8

SynbolThickness mm

27 P 100

0.27

0.30

0.35

7.65 1.00 max.1.85 min.

27 P 110 1.10 max

27 G 120 1.20 max.1.78 min.

27 G 130 1.30 max.

27 G 140 1.40 max. 1.75 min.

30 P 110 30 P 120

1.10 max. 1.20 max.

1.85 min.

30 G 130 1.30 max.1.78 mm.

30 G 140 1.40 max.

30 G 150 1.50 max. 1.75 min.

35 P 125 1.25 max.1.85 min.

35 P 135 1.35 max.

35 G 145 1.45 max.1.78 min.

35 G 155 1.55 max.

35 G 165 1.65 max. 1.75 min.

U.S.A

AISI (1983)

MAXIMUM CORE LOSSES*ELCTRICAL STEELS

GRAIN ORIENTED FULL PROCESSED ASTM A665

ASTM Type

Former AISIType

Thickness Maximum Core Loss at 15 kg (1.5 T) ™*™

W/lb W/kg

Inch mm 60 Hz 50 Hz 60 Hz 50 Hz

27G053 30G058 35G066

M-4 M-5 M-6

0.0106 0.01180.0138

0.270.300.35

0.530.580.66

0.400.440.50

1.171.281.46

0.890.971.11

MAXIMUM CORE LOSSES*ELCTRICAL STEELS

GRAIN ORIENTED FULLY PROCESSEDASTM A725

ASTM Type

Former AISI Type

Thickness Maximum Core Loss at 17 kg (1.7 T)

Inch mm W/lb 60 Hz W/kg 50 Hz

27H076 30H083 35H094

M-4 M-5 M-6

0.0106 0.0118 0.0138

0.270.300.35

0.760.830.94

1.271.391.57

GERMAN

DIN 46400 : Blatt 3 (1983)

Magnetic and technological properties of oriented magnetic steel sheet and strip

Grade Nominal thickness mm

Specific total loss 1) W/Kg max

Magnetic Flux density2) t

min. B8

Code Number Material Number P 1,5 P 1,7

VM 89-27 1.0865 0.27 0.89 1.40 1.75

VM 97-30 1.0861 0.30 0.97 1.50 1.75

VM 111-35 1.0856 0.35 1.11 1.65 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.

GradeMaximum specific total loss

W/kg

35M7 35M6 30M6 30M5 28M5 28M4

1.23 1.11 1.07 0.97 0.95 0.89

However for the last couple of years the emphasis has been shifted from the guaranteed wattloss/Kg at 1.5

T/50 Hz to 1.7 T / 50 HZ as can be seen in IS.3024 - 2006 Chart given Below.

Table 1 Magnetic Properties of Conventional Grain Oriented (CGO)

Electrical Sheet Tested at 1.7 Tesla and 50 Hz.

Grade(1)

Nominal Thicknessmm(2)

Maximum specificCore Loss (W/kg)At 1.7 Tand 50 Hz(3)

MinimumPolarizationin Testla at a Field strengthof 800A/m(4)

MinimumStackingFactor(5)

23CG110 0.23 1.10 1.78 0.945

23CG120 0.23 1.20 1.78 0.945

23CG127 0.23 1.27 1.75 0.945

27CG120 0.27 1.20 1.78 0.950

27CG130 0.27 1.30 1.78 0.950

27CG140 0.27 1.40 1.75 0.950

30CG130 0.30 1.30 1.78 0.955

30CG140 0.30 1.40 1.78 0.955

30CG150 0.30 1.50 1.75 0.955

35CG145 0.35 1.45 1.78 0.960

35CG155 0.35 1.55 1.78 0.960

35CG165 0.35 1.65 1.75 0.960

NOTE : The above samples are sheared longitudinal to the rolling direction and then stress relief annealed in a

neutral or reducing atmosphere to develop magnetic property at 780° C to 820° C. 

Table 2 Magnetic Properties of High Permeability Grain Oriented (HPGO)

Electrical Sheet Tested at 1.7 Tesla and 50 Hz.

Grade(1)

Nominal Thicknessmm(2)

Maximum specificCore Loss (W/kg)at1.7 T and 50Hz(3)

MinimumPolarizationIn Testla at a Field strength of 800A/m(4)

MinimumStackingFactor(5)

23HP90 0.23 0.90 1.85 0.945

23HP95 0.23 0.95 1.85 0.945

23HP100 0.23 1.00 1.85 0.945

23HP100 0.27 1.00 1.85 0.950

23HP110 0.27 1.10 1.85 0.950

23HP110 0.30 1.10 1.86 0.955

23HP120 0.30 1.20 1.85 0.955

23HP125 0.35 1.25 1.85 0.960

23HP135 0.35 1.35 1.85 0.960

NOTE : The above samples are sheared longitudinal to the rolling direction and then stress relief annealed in a

neutral or reducing atmosphere to develop magnetic property at 780° C to 820° C.

CRNO STANDARDS

Given below are IS-648 CRNO standards

SI No.

Designation

Nominal Thickness mm

Max Core Loss at 50 Hz (W/kg)

a.c. Magnetisation 50 (Hz) mln. Value of B Max Tesla

Anisotropy of total specific loss at 1.5 T (%max)

No. Of Bends (mln) assumed density Kg/dm*1.0 T 1.5 T

2500 A/M

5000 A/m

10000 A/m

1 2 3 4 5 6 7 8 9 10 11

I 35C250 1.00 2.50 1.49 1.60 1.70 + / - 17 2 7.60

II 35C270 1.10 2.70 1.49 1.60 1.70 + / - 17 2 7.65

III 35C300 0.35 1.20 3.00 1.49 1.60 1.70 + / - 17 3 7.65

IV 35C330 1.30 3.30 1.49 1.60 1.70 + / - 17 3 7.65

V 35C360 1.45 3.60 1.49 1.60 1.70 + / - 17 3 7.65

VI 50C270 1.10 2.70 1.49 1.60 1.70 + / - 17 2 7.60

VII 50C290 1.15 2.90 1.49 1.60 1.70 + / - 17 2 7.60

VIII 50C310 1.25 3.10 1 49 1.60 1.70 + / - 14 3 7.65

IX 50C330 1.35 3.30 1.49 1.60 1.70 + / - 14 3 7.65

X 50C350 1.50 3.50 1.50 1.60 1.70 + / - 12 5 7.65

XI 50C400 0.50 1.70 4.00 1.53 1.63 1.73 + / - 12 5 7.70

XII 50C470 2.00 4.70 1.54 1.64 1.74 + / - 10 10 7.70

XIII 50C530 2.30 5.30 1.56 1.65 1.75 + / - 10 10 7.70

X!V 50C600 2.60 6.00 1.57 1.66 1.76 + / - 10 10 7.75

XV 50C630 2.8 6.3 1.55 1.65 1.76 + / - 10 10 7.75

XVI 50C700 3.00 7.00 1.60 1.69 1.77 + / - 10 10 7.80

XVII 50C800 3.60 8.00 1.60 1.70 1.78 + / - 10 10 7.80

XVIII 65C330 1.35 3.3 1.49 1.6 1.7 + / - 15 2 7.60

XIX 65C350 1.50 3.50 1.49 1.60 1.70 + / - 14 2 7.60

XX 65C400 1.70 4.00 1.52 1.62 1.72 + / - 14 2 7.65

XXI 65C470 2 4.7 1.53 1.63 1.73 + / - 12 5 7.65

XXII 65C530 0.65 2.30 5.30 1.54 1.64 1.74 + / - 12 5 7.70

XXIII 65C600 2.60 6 1.56 1.66 1.76 + / - 10 10 7.75

XXIV 65C700 3 7 1.57 1.67 1.76 + / - 10 10 7.75

XXV 65C800 3.60 8 1.60 1.70 1.78 + / - 10 10 7.80

XXVI 65C1000 4.40 10 1.61 1.71 1.80 + / - 10 10 7.85

XXVII

100C1000 1 4.40 10 1.58 1.68 1.76 + / - 16 10 7.80

XXVII

100C1300 5.80 13.00 1.60 1.70 1.78 + / - 6 10 7.80

Common CRGO Standards TodayEarlier, most CRGO Mills generally used the old AISI/ASTM nomenclature of M3, M4, M5 & M6 for designating the grade of CRGO Steel. However, now standards are being followed where the CRGO nomenclature guarantees Watt Loss/Kg at 1.7 Tesla and 50Hz. Examples are as follows:

IS - 3024: 2006 CRGO grades are designated as follows:

One hundred times the nominal thickness in mmMaterial symbol CG (Conventional Grade) or HP (High

Permeability) grades

Guaranteed value of iron loss

A value 100 times the iron loss at a frequency of 50 Hz and flux density of 1.7 Tesla

IEC Standard Geneva Switzerland International Standard IEC-60404-8.7:2000

This international standard also has magnetic properties for conventional grade and high permeability grade similar to IS-3024:2006

Example of Conventional Grade, of IEC is M.120 27 S5Example of high permeability grade of IEC is M.100 27 P5

Formerly most CRGO Mills were generally using the former AISI/ASTM nomenclature of M3, M4, M5 & M6 for designating the grade of CRGO Steel. However, now most standards follow a system where the CRGO nomenclature guarantees Watt Loss/Kg at 1.7 Tesla and 50Hz. Examples are as follows:

One hundred times the nominal thickness in mm.Material symbol CG (Conventional Grade) or HP (High Permeability) grades. Guaranteed value of iron loss. A value 100 times the iron loss at a frequency of 50 Hz and flux density of 1.7 Tesla.

Common CRGO Standards Today

JAPANESE STANDARDS: - JIS C 2553:2000

Nippon Steel Corporation follows the same system. Examples are as follows: -

Orient Core:- 27 Z120 means 0.27mm thickness and watt loss of 1.2 w/kg. at

(Symbol Z) 1.7T/50Hz.

Orient Core HI-B:- 27 ZH 90 is a HI-B material, 0.27mm thick and watt loss of

(Symbol ZH) 0.90 watts/kg at 1.7T/50Hz.

Orient Core HI-B-LS:-23 ZDKH 85 is a HI-B-laser scribed material with thickness 0.23mm and watt loss of 0.85 watts / kg. at 1.7 T

AMERICAN STANDARDS: - AISI:1983

American standards generally follow the AISI 1983 where Watt Losses are specified in Watts/Lb. at 60 Hz. Even today the M series is the common nomenclature for conventional grades like M3, M4, M5, M6. For HI-B materials American nomenclature is MOH, M1H, M2H, M3H. AK Steel has also come out with TRAN COR DR (Domain Refined) laser scribed steel with following watt losses, (comparable to Nippon ZDKH)

Description Thickness (mm) Guaranteed Losses Typical Watt Loss

At1.7T/50Hz. At1.7T/50Hz.

TRAN-COR-H0 DR 0.23 0.85 0.78

TRAN-COR H-1 DR 0.27 0.95 0.88

TRAN-COR-H-2 DR 0.3 1 0.95

EUROPEAN STANDARDS:- EN 10107 : 2005

This standard will generally be denoted by M followed by 3 digit number and thickness code and ending with S or R

(S is for conventional grades and P is for HI-B grades.)

Example-M 130 27 S: will mean 0.27mm thick with watt loss of 1.30 Watts/Kg. at 1.7T/50 Hz. (conventional grade), 

Similarly M103: will mean 0.27mm thick with watt loss of 1.03 Watts/Kg. at 1.7 T/50Hz. (HI-B grade).

RUSSIAN STANDARDS- GOST21427.1-83

The Russian standard is unique and different from other standards. Their Steel grades have 4 digit numbers ranging

from 3404 to 3415. 3405 to 3408 are the most popular grades being used. Core losses are as follows:- 

Selecting the proper width and grade of CGRO coils.

1. Winding of Toroidal Core as per customers requirements and tolerance for ID, OD and HT.

2. Inspect wound core for dimensions.

3. Arrange cores in SS basket and load the same in annealing furnace.

4. Carry out the annealing cycle as per work instruction laid down.

5. After annealing is done every core is tested for electrical AT/cm value as specified by customer or as per our

internal standards.

6. All readings of electrical values noted in register and proper stickers with core identification no. are stuck on

every toroidal core.

7. All cores packed in wooden boxes with cushioning material and boxes are securely strapped with steel

straps.

8. Packing list is fixed on every box.

Thickness (mm) Steel Grade Max. Core Loss At 1.7 T/50Hz.

0.3 3405 1.4

0.3 3406 1.33

0.3 3407 1.26

0.3 3408 1.2

0.27 3405 1.38

0.27 3406 1.27

0.27 3407 1.2

0.27 3408 1.14

- Mitred Transformer Laminations 

- Step Lap Laminations (All Types) 

- Slit Coils

B-H Curves for Toroidal Cores

Torodial cores and CT manufacturer need to know the B-H values of CRGO materials.

Given below are and B-H value s 27MOH, M4 and M5 material

M-OH (0.27 mm) M-4 (0.27 mm)

M-5 (0.30 mm)

Manufacturing ProcessSLITTING

Select the proper grade coil and slit the same as per slitting plan.

Modern Method of Cutting:-Load the Appropriate Coil and cut the laminations as per the work instructions given, 

:: Company Video

Conventional Method of Cutting:-MITRING

A) Do the mitring (cutting at 45 degrees angle) operation as per customer's drawing

and maintaining grain direction along length.

B) Complete the V notching and holing operations as per customer's drawing. 

C) Inspect lamination at every stage as per internal Tolerance Chart or tolerances

specified by customer.

D) Anneal lamination in Roller Health annealing furnace. 

E) Check and record losses after annealing. 

F) Weighment, Final Inspection and Packing of Lamination on wooden pallets with

Lamination covered with poly tarred Hessian and secured with steel strap 

G) Attach copy of packing List on every pallet.

Toroidal Core Process1. Selecting the proper width and grade of CGRO coils.

2. Winding of Toroidal Core as per customers requirements and tolerance for ID,

OD and HT.

3. Inspect wound core for dimensions.

4. Arrange cores in SS basket and load the same in annealing furnace.

5. Carry out the annealing cycle as per work instruction laid down.

6. After annealing is done every core is tested for electrical AT/cm value as specified by customer or as per our

internal standards.

7. All readings of electrical values noted in register and proper stickers with core identification no. are stuck on

every toroidal core.

8. All cores packed in wooden boxes with cushioning material and boxes are securely strapped with steel

straps.

9. Packing list is fixed on every box

Core Frame Assembly Process1. Ensure all core frame parts and insulation boards are available.

2. Assemble core frame as per customers drawing. Ensure proper tightening of

tie rods, cross bolts etc.

3. Wind dummy turns around all three limbs and connect the wire for N.L.L

testing.

4. Connect leads from power source to core connection and also connect

Yokogawa leads to transformer turns.

5. Gradually increase voltage of power source to 250 volts (3 watt meter method).

6. Observe N.L.L. of each phase and also note the current readings. Note frequency.

7. Transfer data to P.C to get a comprehensive report.