IEC 60404-2 pdf download Magnetic materials – Part 2: Methods of measurement of the magnetic properties of electrical steel strip and sheet by means of an Epstein frame
1 Scope and object
This part of lEC 60404 is applicable to grain oriented and non-oriented electrical sheet andstrip for a.c. measurements of magnetic properties at frequencies up to 400 Hz and for d.c.magnetic measurements.
The object of this part is to define the general principles and the technical details of themeasurement of the magnetic properties of electrical steel sheet and strip by means of anEpstein frame.
The Epstein frame is applicable to test specimens obtained from electrical steel sheets andstrips of any grade.The a.c. magnetic characteristics are determined for sinusoidal inducedvoltages, for specified peak values of magnetic polarization and for a specified frequency.
The measurements are to be made at an ambient temperature of (23 ± 5) C on testspecimens which have first been demagnetized.
Measurements at higher frequencies are to be made in accordance with lEC 60404-10.
NOTE Throughout this standard the term “magnetic polarization” is used as defined in lEC 60050(221). In somestandards of the lEC 60404 series, the term “magnetic flux density” was used.
2 Normative references
The following referenced documents are indispensable for the application of this document.Fordated references,only the edition cited applies. For undated references, the latest edition ofthe referenced document (including any amendments) applies.
IEC 60050-221，International Electrotechnical Vocabulary – Chapter 221: Magnetic materialsand components
IEC 60404-4,Magnetic materials – Part 4: Methods of measurement of d.c. magnetic propertiesof magnetically soft materials
IEC 60404-8-3，Magnetic materials – Part 8-3: Specifications for individual materials – Cold-rolled electrical non-alloyed and alloyed steel sheet and strip delivered in the semi-processedstate
IEC 60404-8-4，Magnetic materials – Part 8-4:Specifications for individual materials – Cold-rolled non-oriented electrical steel sheet and strip delivered in the fully-processed state
IEC 60404-8-7，Magnetic materials – Part 8-7: Specifications for individual materials – Cold-rolled grain-oriented electrical steel sheet and strip delivered in the fully-processed state
IEC 60404-10，Magnetic materials – Part 10: Methods of measurement of magnetic propertiesof magnetic sheet and strip at medium frequencies
IEC 60404-13，Magnetic materials – Part 13: Methods of measurement of density，resistivityand stacking factor of electrical steel sheet and strip
3 General principles of a.c. measurements3.1 Principle of the 25 cm Epstein frame method
The 25 cm Epstein frame which comprises a primary winding,a secondary winding and thespecimen to be tested as a core,forms an unloaded transformer whose characteristics aremeasured by the method described in the following subclauses.
The strips to be tested are assembled in a square, having double-lapped joints (see figure 1).thus forming four branches of equal length and equal cross-sectional area.
The strips shall be sampled in accordance with the appropriate product standard in the lEC60404-8 series.
They shall be cut by a method which will produce substantially burr-free edges and, if sospecified, heat treated in accordance with the corresponding product standard.They shall havethe following dimensions:
– width b = 30 mm ±0,2 mm;- length 280 mm sl≤ 320 mm.
The lengths of the strips shall be equal within a tolerance of +0,5 mm.
When strips are cut parallel or normal to the direction of rolling, the edge of the parent sheetshall be taken as the reference direction.
The following tolerances shall apply for the angle between the specified and actual direction ofcutting:
士1° for grain oriented steel sheet;士5° for non-oriented steel sheet.
Only flat strips shall be used.Measurements shall be made without additional insulation.
The number of strips comprising the test specimen shall be a multiple of four and is specifiedin the corresponding product standard.However, the active mass of the test specimen (seeequation (1)) shall be at least 240 g for strips 280 mm long.