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The Steinmetz switching is the balance switching for the operation of 1-phase induction furnaces from 3- phase rotary current networks. In the case of Steinmetz switching, it is assumed that the compensation of the 1-phase furnace is set to 1. By means of balance control, the capacitive part of the balancing is switched in sequence with the inductive part, i.e. the capacity of the balancing condensers equals the output of the choke. By means of corresponding condenser stage switching, condensers are switched in parallel to the choke or the balancing condensers. The level of the balancing performance depends on the output being absorbed by the induction furnace. The ideal figure is the furnace output divided by 1.73. Since a crucible induction furnace is designed so that it can still be operated at nominal load even with approx. 25% washing-out, the transformer steps must be designed in the

same way. The balancing must thus have a sufficient capacity even at correspondingly low furnace voltage. With a 12.5-t furnace with 3,000 kW output at 2,600 V, the voltage steps for the same output would be arranged as follows: 2,600V, 2,490V, 2,380V, 2,270V. The balancing must be designed to cater for this lowest voltage, so that at this voltage, the condenser output still has the required 1,735 kVar and the choke the required 1,735 kVA. At 2,600 V, the balancing condensers thus have 2,275 kVar and the choke 2,275 kVA as the nominal output.

Erosion is the carrying away of material from the surface of components, due to the action of liquids, vapours or gases flowing past them.

Mould weights are weights of cast iron, which are placed on top of sand moulds ready for casting, in order to counteract the upward pressure of the casting mould.

Charging usually refers to the filling of a casting furnace with the materials to be melted. For small furnaces with a capacity of up to 1 t, charging can be carried out by hand. For larger furnaces, mechanical lifting equipment is used.

Decay refers to the loss of alloy elements. The loss of magnesium content during storage and casting of nodular cast iron in larger containers is the most frequent application of the term decay.

Skimming is generally carried out after reaching the tapping filling level. In most cases, a slag forming agent is applied to the bath, and then removed with manual equipment or pneumatic slag removers.
The tools used must be treated in advance with blackening to facilitate subsequent removal of the slag. Tools must be heated and dried over the bath before immersion in the liquid melt.

Racking off is the removal of slag from the surface of the bath. Racking off is also used to refer to the removal of auxiliary casting materials from bunkers with the aid of mechanical devices.

Material condition specifies the condition of a material – solid, liquid or gaseous.

A cover extraction hood is a combination of an internal cover, fitted with an extraction hood enclosing the cover. This type of extraction has proven itself well in practice, and is used almost exclusively for high-output furnaces. The hood can be adapted to meet the corresponding requirements by means of set opening angles, and can for example remove all the smoke during charging. Another option is the fitting of this extraction system with automatically opening slots in the frontal area for smoke extraction directly in front of the crucible furnace during the production of nodular graphite iron.

Cover drives for crucible induction furnaces are available in a wide range of versions. Flap covers or sliding covers are normally operated by means of differential cylinders and chains. If cover hoods are being used, the drive takes the form of 2 differential cylinders. Swivel covers are driven via a curved roller and guide cylinder by means of a vertically acting plunger cylinder. The lowering takes place under the own weight of the cover and the piston rod. In case of certain special requirements, a small differential cylinder can also be used.