- Year: 2012
- Where: USA
- Product:Three-phase furnace transformers
Italian Tailor Made
Construction type: single-core (five columns) with two windings and on-load control of secondary voltage.
Transformers for alternating current electric-arc furnaces (AC EAFs) are utilised throughout the steel industry. They are used to power arc furnaces for the production of steel, which require high levels of power that must also be variable due to the frequent short-circuits, and also to power arc furnaces for the production of special alloys – these alloys often require the deployment of three single-phase furnace transformers instead of a single three-phase transformer.
These transformers must be designed to resist the high levels of electrical, thermal and mechanical stress to which they are subject during utilisation.
Other elements that must be taken into consideration when designing transformers for electric-arc furnaces are the high secondary currents required for the fusion process (dozens of kA) and the wide range of secondary voltages, which are normally regulated by an on-load tap changer (OLTC), either directly on the high-voltage winding or via an intermediate booster located within the same tank.
An additional option that is now often used in furnace transformers is the closure of the secondary electrical circuit (triangle) within the transformer tank. Furnace transformers are often used in series with an on-load tap changer (OLTC) or a no-load tap changer (NLTC), which serves to enhance the stability of the arc. The reactor can be built inside the main transformer cabinet, or alternatively, it can be entirely separate from it or located next to it.
This solution makes it possible to eliminate the costs of cabling the MV connections between the transformer and the reactor, thus making it possible to carry out maintenance work on the reactor without having to shut off the transformer. In this way, the overall reliability of the system can be enhanced.
The experience that TES has built up has allowed to company to become a leading brand both nationally and internationally in the furnace transformers market. The company’s products are used across a wide spectrum of applications by a plethora of major clients.