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Technical Notes

Benefits of Toroidal Transformer Design
Efficiency: The toroidal form of transformer offers excellent efficiency for a given size and weight. 

The toroidal core provides a virtually perfect magnetic circuit, eliminating the inherent air gaps of conventional laminated-bobbin transformers. Higher flux densities, along with full utilization of the core area, result in a smaller component-typically 50% of the size and weight of laminated components. The overall efficiency of toroidals is typically 90 to 95%, and with custom design can be even higher. Due to the high quality, tightly wound, grain-oriented silicon steel core, very low core losses and off-load magnetizing currents can be achieved, adding to the overall efficiency. 

Low noise and low stray flux field: Because the magnetic circuit is so complete, and due to the uniform distribution of the windings over the core, a toroidal transformer is very quiet in operation-with low or even zero mechanical hum caused by magnetostriction. Toroidal transformers also exhibit very low levels of noise-inducing stray magnetic fields (typically 8 times lower than laminated stack type transformers). This makes the toroid the perfect choice for sensitive electronic systems such as high-gain preamplifiers and instrumentation.

Good regulation: The winding configuration of toroidal transformers results in very low leakage inductance. This inductance is produced when a percentage of the magnetic flux produced by the primary is not utilized by the secondary, therefore not generating any voltage-a common characteristic of laminated stack transformers. Because toroidal winding results in tight coupling, virtually all the flux is utilized (and not left to radiate and interfere with circuitry). This enables tight regulation, with off-load secondary voltages lower than laminates. In addition, lower copper loss results in less power being wasted as heat.

Ease of mounting: The majority of toroidal transformers are mounted with one central screw, speeding production time and lowering the parts count of mounting hardware. For special applications, custom mounting methods can easily be provided for greater production efficiency.

Packaging versatility: A toroidal transformer with specific characteristics can be varied in height and diameter to meet product-design requirements. This enables the transformer to meet enclosure space constraints. Tall cylinder or flat disc styles can be produced to meet retrofit space requirements or low-profile applications.

Markings: Avel Lindberg Standard Toroidal Transformers comply with most of the world's major safety standards (including UL506, UL2601, UL1411, and UL1950) and are built under our UL- and CSA-recognized design and construction files. Custom designs can be manufactured to comply with most other standards, whether European, medical, military, or commercial. All Avel transformers are CE marked.

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