Transformers and Their Variants

Transformers are integral components of an electrical circuit, ubiquitous among home and office power delivery systems. Tasked with increasing or decreasing the voltage of electric energy from one circuit to another, transformers allow small household items, such as cell phones, to charge without being damaged by inappropriate voltage. With a wide range of transformer designs existing in the electronics environment, it is critical to be familiar with the most common types and their associated applications. In this blog, we will discuss the basic operating principle of transformers, while also covering the various ways these elements may be classified.

Transformers may be characterized by their voltage level, core material, winding arrangement, or usage. With further subdivisions in each of these categories, it becomes apparent why so many transformer designs exist. Although electricians and other industry experts speak with more nuance about certain transformer characteristics, the most commonly discussed aspect is the voltage level.
 
Voltage Level
 
1. Step Down Transformers 

The supply voltage used in the United States and Europe is 120V and 220V, respectively. Both of these values far exceed the operational voltage of most devices and appliances which range from 5V, 6V, 9V, to 24V. If these devices were subject to an overvoltage of that magnitude for a long period, they could potentially fail or increase the likelihood of other hazardous events, such as fire. Transformers help the circuit deliver the appropriate voltage level by creating a primary-to-secondary winding ratio greater than one.
 
 2. Step Up Transformers
 
Step-up transformers are most commonly used to aid in power transmission. By increasing the voltage, power loss is significantly decreased over long transmission lines. They also allow for the implementation of thinner conductor lines which cuts investment costs for large power grids. Step-up transformers utilize the inverse technology of step-down transformers, featuring more windings on the secondary side of the circuit. This means that industrial equipment that runs on higher voltage requirements can be satisfied through these devices.
 
Core Material 
 
1. Iron Core 
Transformers operate using mutual induction, in which one coil receiving an alternating current energizes a nearby coil using a magnetic field. Soft iron, being a highly ferromagnetic material, is best suited to minimize core losses and increase efficiency. It is also a relatively cheap material, permitting ease of access for most consumers and cost savings for producers.
 
2. Toroidal Core Transformer
 
Toroidal transformers implement a donut-shaped magnetic core. This design allows the transformer to be more compact, saving on material cost and overall weight. Further, toroidal cores feature a shorter distance between each core end, causing lower secondary impedance and higher electrical performance. The ring shape also contains the magnetic flux to a smaller area, preventing the damaging electromagnetic interference (EMI) that may persist with straight cores.
 
3. Air Core Transformer
 
Air core transformers are similar in design to iron core transformers, although they lack a ferromagnetic medium. This allows the device to be lightweight and compact but features the lowest mutual inductance of any design. As such, the use of air-core transformers is generally limited to radiofrequency and wireless charging applications.
 
Conclusion
 
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