Standard transformers are directly connected to the grid: their operating frequency is the same as the grid (16.67, 50 or 60 Hz).
WHY ARE THE MEDIUM FREQUENCY TRANSFORMERS MORE EFFICIENT?
Both the magnetic flux and the number of turns on a winding are inversely proportional to the frequency. Assuming a constant flux density, a higher frequency dramatically reduces the core cross-section and the number of turns on a winding, with a consequently smaller transformer, with reduced conductors length, hence less electrical resistance: this is the reason why medium frequency transformers are more efficient than standard ones.
In case the weight or dimension of the transformer become an issue (like in traction applications), the usage of medium frequency transformers is determined. These transformers work with fundamental frequencies of several kHz. This feature brings consequences on the behaviour of the materials. The medium frequencies content in the current deeply impact copper losses: the right solution is the usage of litz wires, which allow to split winding conductors into many parallels with very low sections, to creating extra-compact windings.
De Angeli Prodotti offers a wide range of Litz wires production, to satisfy the challenges of new generations of transformers, reconfirming once again the innovative content inside the products of the brand.