What is transformer,working principle of transformer, Types and difference between core type and shell type transformer
A transformer is an electrical device used to transfer electrical energy between two or more circuits through electromagnetic induction. It consists of two or more coils of wire, known as windings, wound around a common magnetic core.
Working principle of Transformer
- Basically, the operating principle of a transformer is based on electromagnetic induction. It consists of a primary coil and a secondary coil wound on a common core. When alternating current (AC) flows through the primary coil, it creates a changing magnetic field around the core.
- This changing magnetic field induces a voltage in the secondary coil through electromagnetic induction, which transfers energy between the two coils.
- A transformer's turns ratio determines the voltage conversion between the primary and secondary coils, so the voltage can be raised or lowered depending on the winding configuration.
Transformers can be divided into several types based on their design.
1. Core transformer
In this design, the core is rectangular or circular frame shape. The primary and secondary windings are wound on separate branches of the core. This type provides good mechanical support, but losses may be high due to leaky flow.
2. Shell-type transformer
Here, the core surrounds both the primary and secondary windings. The windings are wound concentrically around the legs of the core. This design improves efficiency by reducing stray flux and providing better magnetic coupling.
3. Autotransformer
An autotransformer has one winding that serves as both a primary and a secondary winding. This design is often used for voltage regulation and applications requiring small voltage changes.
4. Two-winding transformer
This is the most common type with separate primary and secondary windings. Used when significant voltage conversion is required.
5. Toroidal transformer
In this design, the core is toroidal (donut) and two windings are wound around it. Toroidal transformers are suitable for sensitive electronic equipment due to low leakage flux and electromagnetic interference.
6. Ferrite Core Transformers
Ferrite cores made of ceramic materials are used for high frequency applications. These transformers are compact and offer good performance at higher frequencies.
7. Air core transformer
In this type, the windings are wound around a non-magnetic core (usually air). These transformers are used in radio frequencies and provide low coupling between windings. Each type of transformer design has its own advantages and disadvantages, making it suitable for different applications depending on factors such as efficiency, size, weight and frequency of operation.
Differences between core type and shell type transformers:
Core type transformer
1. Core design:
In a core transformer, the core is in the form of a rectangular or circular frame. It consists of two parallel branches, with the primary and secondary windings wound on separate branches.
2. Winding position:
The primary and secondary windings are wound concentrically around each end of the core. Wind the primary winding first, then the insulator, then the secondary winding. This arrangement increases the distance between the windings, increasing the risk of flux leakage.
3. Leakage flux:
Due to the distance between the windings and the core, the leakage flux (the flux that does not bind the two windings) is higher in core transformers. This can increase losses and reduce efficiency.
4. Mechanical support:
The core transformer provides excellent mechanical support to the windings due to its rigid frame. Therefore, it is suitable for high power applications.
Shell type transformer
1. Core design:
In cased transformers, the core surrounds both the primary and secondary windings. The windings are wound concentrically around the legs of the core.
2. Winning pattern:
The primary winding is wound first, then the insulator, then the secondary winding. The windings are wound close to the core to improve magnetic coupling and reduce leakage flux.
3. Leakage flux:
Leakage flux in jacketed transformers is greatly reduced because the windings are close to the core. This improves efficiency and reduces losses.
4. Mechanical support:
Shell type transformers may not provide as much mechanical winding support as core transformers, but better magnetic coupling and less leakage flux compensate for these limitations.
Key differences:
1. Efficiency:
Shrouded transformers are generally more efficient due to less leakage flux and better magnetic coupling. This can reduce losses and improve overall performance.
2. Size and weight:
Due to their improved design, shell-type transformers are generally smaller and lighter than core-type transformers at the same rated power.
3. Applications:
Shell type transformers are often preferred for applications that demand higher efficiency and compact size, such as distribution transformers. Core type transformers find application in power transformers and where higher mechanical support is required.
4. Cost:
Core type transformers may be more cost-effective for lower power ratings, but as power levels increase, shell type transformers' efficiency benefits might outweigh any cost differences.
Conclusion:
while both core type and shell type transformers serve the purpose of voltage transformation, their differences in winding arrangement, leakage flux, efficiency, and mechanical support make them suitable for different applications based on specific requirements and constraints.
