2 May 2013 – Powertech Transformers, a subsidiary of Powertech and the JSE listed Altron group, recently installed in its Pretoria laboratory, Brockhaus equipment which is used for testing of core steel, making it the only company in Africa with this type of equipment and one of only a few companies in the world.

The equipment includes the following:

An Epstein Frame: The purpose of the instrument is to measure the properties of ferromagnetic material in transformers and motors. It can measure field strength and hence the losses of the core material. Although this type of instrument employs old technology, it has proven reliability and effectiveness – many international standards refer to the Epstein test – IEC 60404-11, ASTM A717-93 and JIS C 2550

Single sheet sensor tester 250 x 250 mm: In addition to the Epstein Frame tester, this unit measures the material properties. It produces the loss measurement of the material. This instrument can measure internal stress of the material due to handling. The results can be converted to Epstein Frame results. This is the latest technology in core steel measurement, but many standards still enforce Epstein Frame Test results.

Stacking factor tester: Measurements are performed with the stacking factor tester in accordance with IEC 60404-13 to determine the filling factor of the core steel packet space factor. The ratio of core material to other material, e.g. oil, pressboard and particles in the close proximity of the core is determined.

Franklin tester: The Franklin tester for surface resistance is used to determine the quality aspects of soft magnetic materials and also measures surface resistance; resistance distribution as well as the thickness of the coating on electrical steel and punched parts (in extreme cases).

The advantages of accurate core steel property measurements are as follows:

  • When test results, e.g. loss measurements on core material certificates arrive from suppliers, the accuracy thereof can be verified. It enables early detection of major loss fluctuations in the no-load losses.
  • Calculation and manufacturing of the core to such an extent as to achieve the optimal filling factor.
  • Ability of measuring the insulation resistance during manufacturing and decreasing loss deviations based on material handling.

Powertech transformers supplies transformers from generator step-up to transmission and distribution transformers.