The Magnetic Circuit (Core)


ETS specializes in the manufacture and supply of step-lap cut cores & stacked cores. The iron cores are manufactured with cold rolled grain oriented electrical sheet steel having thicknesses of 0.30mm, 0.37mm and 0.23mm. In power transformers, these are also of the HiB variety (including laser-etched material), depending upon the required no-load loss levels. The most economical cross section is achieved by proper selection of particular widths. All our cores are of cruciform section and are of the core type (3 limbs with no outer return paths). The laminations are thinly insulated on both sides, allowing for a good stacking factor for the core.

The equipment for cutting comprises multiple fully automatic CNC core cutting machines, supplied by GEORG, Germany. It can handle upto 600mm widths. Laminations are automatically stacked using a brake hammer.

All the cores are mitred and step lap cut which gives a benefit in no-load losses and noise level. For ratings upto 8 MVA, we can have wooden clamping structure made up of compressed resin bonded wood pressure plates and beams. In higher ratings, the clamping structure is a combination of wooden compression rings pressed and held in position by steel clamps. The limbs have no compression bolts (core bolts). In their place, we use glass fiber bonds (tightened insulated bonds). The compression at the ends of the clamping structure is maintained by core end bolts.

The step-lap construction and the holes in the cut core ensure gap free assembly of cores, which results in reduction of Iron losses, magnetizing currents and noise levels. Stacked cores are produced for in-house consumption as well as for exports to clients worldwide. In addition to supplying the GCC market, this also enables the Company's products to meet stringent environmental requirements of the European market.