The lifetime of a coil
The lifetime of a coil is mainly affected by its ability to withstand the dielectric, mechanical, thermal, and chemical influences that act on the coil during the operation of the induction furnace.
Reduction in the insulation properties of the coil
One of the most common causes of fusion system failure is a reduction in the insulation properties of the coil. This is due to the failure of the insulating varnish. Insufficient water flow through the coil (overheating), under-tightened shunts and bolts (vibrating coil), and clogged metal can also cause insulation fatigue. At the points of damage, the coil is sensitive to conductive dust and moisture, which can cause inter-winding short circuits. Sparking between the coils will burn and melt the remaining insulation.
This is why we place emphasis on the quality of the insulation materials and their implementation on the coil. Only insulating varnish with high dielectric strength, temperature, mechanical and antioxidant resistance is suitable for use with high voltage inductors.
The quality and grade of the insulation materials
The insulating banding strips must be perfectly homogeneously layered throughout the coil profile without major overlaps or gaps. The impregnation of the varnish is carried out in several layers. The thickness of the varnish is measured at the reference points of the coil.
Depending on the insulating varnish used, the coil is heated in a resistance furnace according to a prescribed drying curve. The drying furnace must be equipped with sufficient ventilation to remove air moisture, which has an adverse effect on the subsequent strength and durability of the paint.
The quality and grade of the insulation materials used has a strategic impact on the safety and economics of the melting plant operation.
The next step of the coil repair is the installation of the coil refractory.
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