Transformers, which are used to transform electrical energy from one circuit to another, were heavier in size and hence difficult to handle in the earlier days. The core on which coils are wrapped decides the shape and size of transformers. The larger the size of the coil, heavier is the transformer. The desire of industries and people for light weight transformers leads to the invention of toroidal transformer.
The primary and secondary coils of a toroidal transformer are winded over the ring or donut-shaped core that allows reduction in the size and weight of the transformers much better that other conventional core. Also, the large diameter and smaller number of windings allows toroidal coils to reduce resistance. Another important feature of the transformer relies in its limited magnetic flux at the core that avoids the energy generated, from being used by other neighborhood objects.
There is virtually no air gap between the coils as the windings are evenly wrapped over the entire core. This allows the transformer to function at a higher flux density compared to other power transformers. It is imperative to fill the gaps among the winds using any insulating material.
The design of these transformers varies based on parameters like power rating, inductance, voltage level, operating frequency, size, impedance, bandwidth, packaging, winding capacitance etc.
Compared to other standard laminated power transformers, toroidal transformers have the following advantages:
- Smaller in size
- Less mechanical hum
- Higher efficiency
- Low leakage
- Low noise
- Lesser electromagnetic interface
- Smaller off-load loss
- Single-bolt mounting
- Vast choice of shapes
- Lower weight
Following disadvantages are associated with a toroidal transformer.
- Limited power capacity
- Unfeasible for some low-voltage circuits
The cores of these transformers are commonly made using materials like Silicon steel, Nickel iron, Moly-permalloy powder, Iron powder, Amorphous and Ferrites. In these materials, Silicon steel and Nickel iron are mainly available as tape-wound cores or laminated pieces. In addition to these materials, non-magnetic toroids are also used in the fabrication of a toroidal transformer.
The service of toroidal transformer is applicable to Aerospace, Transportation, Military Subcontractors, Communications / Data Processing, Pneumatic Systems, Geophysical, Biomedical, Power Supplies, Industrial Process Control, Audio Systems and Clock and Timer Circuits. There are many numbers of reputed manufacturers and suppliers available in the market that provides toroidal transformers of myriad sizes and configurations. Technical personnel at the suppliers end help customers with the technical aspects of the product like toroidal mounting, leads, terminations, and also about the safety measurements, protection and recognition.