Toroidal transformers are those that have a doughnut-shaped cores made of ferromagnetic material like laminated iron, ferrite, or iron powder, around which wire is wound. These transformers are used in a variety of applications like amplifiers, power supplies, and inverters. There are a variety of reasons that make toroidal transformers better than other conventional transformers.
In this article, Miracle Electronics from India outlines the advantages of toroidal transformers over other conventional transformers.
Toroidal transformers are almost half the size and weight of other standard transformers! This is because the ideal shape of the transformer requires least amount of material. Moreover, the windings are symmetrically spread over the entire core, thus making the wire length very short. This smaller size makes it more useful to be used in small compact electrical products.
While the cross-section of a toroidal transformer is held constant, the height and diameter can be altered to accommodate the application. This means that toroidal transformers can be used in applications where other transformers cannot.
Toroidal transformers require only a single center bolt to be mounted. This results in quicker and easier mounting of the transformers, thus reducing assembly time by equipment manufacturers. On the other hand, other standard transformers require four screws to be mounted. Toroidal transformers can be mounted with the help of pressure-less mounting plates, resin center potting with brass inserts, PCB mounting, or complete encapsulation in plastic or metal housings.
Efficiency of a transformer can be defined as the useful output power delivered to the load divided by the power input to the transformer. The difference between these two values is consumed by losses in the core and windings. Toroidal transformers are generally 90-95% efficient, as compared to the efficiency of other transformers, which is generally lesser than 90%. This better efficiency is as a result of the high quality grain oriented steel used in the core, and the windings that are distributed symmetrically over the entire core circumference.
When the windings and core layers vibrate because of the forces between coil turns and core laminations, audible hum is caused in transformers. Moreover, the hum increases over time as the laminations start loosening. But, the construction of toroidal transformers helps to dampen acoustic noise. The core is tightly wound, spot welded, annealed, and coated with epoxy resin. The uniform winding of the core leaves no air gaps, thus leaving no loose sheets to vibrate, ultimately resulting in lower hum. Even if the hum is heard when the power is turned on, it dies down to a quieter level after a few seconds.
Because of the unique construction of toroidal transformers, they radiate about 1/10th the magnetic field of other transformers. This magnetic field transforms energy from primary to secondary, thus eliminating the need for any kind of special shielding, making these equipment highly suitable for applications in sensitive electronic equipment like medical equipment, CRTs, and low level amplifiers.
All the above benefits clearly show why toroidal transformers are much better as compared to other standard transformers.