Furnace Transformers

Arc, Submerged Arc, Ladle , Induction ,
Upto 10 MVA,Upto 33kV,ONAN/OFWF Cooling
A high current furnace transformer is provided by having the low-voltage windings arranged in a closed delta configuration within the transformer enclosure. Bus bar terminals are mounted exterior to the enclosure for providing electrical connection with the low-voltage windings.

Furnace transformers are used to step down from voltages between 11 and 33 kV to levels of several hundred volts only. This results in massive secondary currents. As an example a 30 MVA unit at 150 V would result in a secondary current of 115 kilo Ampere. For these high
secondary currents special bushings are required to connect to the bus-bars. These bushings are specified with very specific arrangements to suit the bus-bar arrangement and cooling system. Furnace bus-bars are mostly water cooled. Due to the high secondary currents and resistive losses the furnace layout is such as to limit the bus-bar length.

The furnace transformers are then located close to the furnace itself and if they are single phase units, arranged in a triangle around the furnace. This means that there is a high risk of fire, a high ambient temperature and this whole set up is located at a level associated with the third story of the building. The location above ground level encourages single phase units due to the structural limitations of the buildings. To reduce the fire risk the transformers are contained in rooms, which adds to the high ambient temperature.