Short-circuit rings

are used in magnetic applications in order to keep the scatter fields away from cer- tain components. In crucible induction furnace design, short-circuit rings are required for furnaces with a high specific output, so that the components mainly in the upper furnace area are not heated excessively by the scatter field. In the bottom area, the electrically conductive parts are further away from the coil than those in the upper area. The short-circuit ring is made of coil copper in a water-cooled design. The ring is usually fitted above and behind the iron piles, in order to gen- erate an opposing field to the scatter field. By reason of the induction law, the mag- netic field generated is arranged in opposition to the generating magnetic field.

In furnaces with high specific outputs, the loss performance in the short-circuit ring can amount to approx.10 kW. The amount of water required to dissipate this energy is approx. 35 l/h and kW, and therefore approx. 350 l/h at 10 kW. The short-circuit ring must be installed electrically insulated from the supporting construction. Casting into the upper concrete ring without any possibility of escape for loss water is not recommended.

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