Three-phase form-wound autotransformers

The three-phase form-wound autotransformers by GTS Elettrotecnica are an efficient and highly cost-effective solution for a wide range of industrial and commercial applications, thanks to their excellent performance-to-cost ratio. Designed to cover a power range from 70 VA up to 50,000 VA, they offer reliability and flexibility in any system configuration.

The term “form-wound” refers to the specific construction technique used: the concentric windings are made on hollow fiberglass formers, inside which the E-shaped magnetic legs are inserted. The magnetic circuit is completed by an I-shaped element, which ensures stable and precise closure of the core. This solution guarantees good energy efficiency and optimal distribution of the magnetic flux, improving heat dissipation and reducing losses. Resin impregnation and its polymerization complete the production process.

As autotransformers, they do not provide galvanic isolation between primary and secondary, and are therefore unsuitable in the presence of heavily unbalanced loads. However, they are an ideal economical option when the difference between the maximum voltage (Vmax) and the minimum voltage (Vmin) is limited. The core power can be calculated using the formula: Core power = ((Vmax – Vmin)/Vmax) × rated power (VA). In addition, the phase connection is generally configured as Ya0 or Yan0, with an angular phase shift optimized for specific application requirements.

A distinctive strength of GTS Elettrotecnica’s three-phase autotransformers on former is their complete customizability: each model can be adapted by varying voltages, mechanical overall dimensions, and accessories, to best meet every design requirement of the customer.

Built in accordance with the strictest standards for safety and electrical insulation, these devices ensure consistent and long-lasting performance, making them the perfect choice for those seeking a compact, efficient, and economically advantageous solution.