Three-phase core-type autotransformers

The three-phase core-type autotransformers by GTS Elettrotecnica represent an advanced and advantageous technical solution for high-power industrial applications, with an operating range from 40 kVA to 1200 kVA. These devices offer a cost-effective alternative to traditional three-phase transformers, while ensuring high performance and reliability.

The construction design provides for the primary and secondary windings to be made directly on the magnetic core legs. The entire assembly, including the legs and the two yokes, is reinforced with metal plates and tie rods and then subjected to vacuum pressure impregnation with epoxy resin (VPI technology). This process is followed by an oven curing phase that gives the structure maximum mechanical stability and the required insulation class.

A key aspect to consider is that, since these are autotransformers, there is no galvanic isolation between the primary and secondary circuit windings. This makes them unsuitable in the presence of unbalanced loads. However, they are an extremely convenient choice when the difference between maximum voltage (Vmax) and minimum voltage (Vmin) is limited, according to the formula: Core power = ((Vmax – Vmin)/Vmax) × rated power (VA). In addition, the phase connection is normally configured as Ya0 or Yan0, with an angular phase shift optimized for specific application requirements.

Another strength of these devices is their high design flexibility: each model can be customized in terms of voltages, physical dimensions, and accessories, to perfectly match the technical requirements of the system.

Thanks to build quality, compliance with the strictest international standards, and the use of selected materials, GTS Elettrotecnica’s three-phase core-type autotransformers are a safe, high-performing, and cost-effective choice for complex, high-power systems.