Last Updated on October 22, 2023 by Kevin Chen
Transformers are electrical devices that change the voltage of an alternating current and change the current flowing through a circuit. They are used on circuits that require low voltage or lower current than standard voltages, or when the load on a circuit requires a special type of wiring.
There are different types of transformers in the market. One of them is the shell type transformer. Would you like to know more about it? Read on as we uncover all the details about shell type transformers.
What is a shell type transformer?
As the name suggests, this transformer has a shell-like structure, made of a single piece of cast iron. It has a primary winding placed around the core and a secondary winding that is connected to the primary winding.
The shell type transformer has two windings, one for the input and one for the output. The shell type transformer is made up of an iron core with two windings, one on each side of the core.
The primary winding is usually connected to the source voltage (in most cases) while the secondary winding is connected to the load, or to another transformer or an electrical load such as an electric motor or lamp post, or even another source of electrical power.
This type of transformer helps convert alternating current (AC) into direct current (DC). This DC can then be stored in batteries or other sources of energy storage devices and then used at a later time.
Shell type transformers are made of cast iron with the primary and secondary windings placed around the core.
Construction of a shell type transformer
The shell type transformer consists of a core made up of soft iron or steel. The primary and secondary windings are placed around the core. The core is housed inside an outer shell, which is usually made up of cast iron or steel. This outer shell protects the transformer from rust and also serves as the main load-bearing structure for the transformer.
The primary winding connects to the high voltage AC source while the secondary winding connects to the load. The windings are wound on top of each other around a laminated soft iron core, which helps in reducing eddy currents in the secondary winding and thus reduces heating losses in it.
The two windings are separated by insulation material such as paper, glass fiber, etc., which provides protection against short circuits between them.
The cores used to make these transformers can be either solid or laminations or a combination of both, depending upon their use and power rating. These cores can be made up of silicon steel laminations, silicon steel solid core or copper laminations, or copper solid core.
The core of a shell type transformer
The core is among the key components of a shell type transformer. Mostly, the ‘L’ and ‘E’ shapes laminations are used for making the cores of these transformers.
The laminations are usually made of silicon steel and are used for primary and secondary windings respectively. The silicon steel is used for improving the core strength which helps in reducing the stress on the core.
The ‘L’ and ‘E’ shapes are used to improve the magnetic permeability of the core, especially for high-power applications.
For this, small squares (or hexagons in the case of hexagonal laminations) are cut out from these laminations with a particular orientation.
Windings of a shell type transformer
In a shell type transformer, the high voltage and low voltage are wound on the cores longitudinally.
The primary winding is wound on the long axis of the core and the secondary winding is on the short axis of the core.
Both windings are connected to each other using insulating tape or a plastic film.
In a shell type transformer, there are two basic types of windings that are wound on each side of a core. These windings are primary and secondary windings respectively.
The primary winding is made up of high voltage and low voltage windings while the secondary winding is made up of intermediate frequency (IF) and high frequency (HF) windings used for power applications.
The two sets of windings are connected to each other by means of an insulator which prevents electrical contact between them, during operation, so as to keep insulation property intact in case they touch each other during operation.
Shell type transformer cooling system
The process of power transformation tends to generate a significant level of heat. This calls for an efficient cooling system.
The transformer is made up of a number of components and each component has some specific cooling requirement.
The core has a cooling system that consists of air and oil cooling.
Air is pumped through the core and blown by a fan through the winding slots to cool it down.
On the other hand, oil is pumped into the core, where it mixes with the airflow to cool down the windings.
The oil flows back to the reservoir through an inlet pipe.
The limb of a shell type transformer
The winding and the coil are wound around a cylindrical core.
The limb core is made up of a number of concentric windings, which are wound in a cyclic arrangement around the cylindrical core.
Limb windings are so designed that the current flowing through them is maximum at one end and minimum at the other end.
The current flows from one end to another, in such a way that it passes through more than one winding. This is called a “commutation”.
A transformer has two or more sets of windings (welds). Each set of windings is called an “armature” or “leg”. The currents flowing through all arms are equal but opposite in polarity. The currents flowing through each armature are equal and opposite in polarity but not necessarily the same in magnitude.
Applications of shell type transformer
Where are shell type transformers used? Is this type of transformer perfect for me?
Shell type transformers are perfect for low voltage applications. Given their designs and construction, they are perfect for those applications that aim at saving the cost of power transformation. They are very efficient in converting power from one voltage to another voltage.
The most common uses of this type of transformer are in the following application fields:
-Transformers for small motors and generators (for example, automotive, agricultural, etc.)
– Transformers for household appliances (for example, vacuum cleaners, washing machines, etc.)
– Transformers for radio frequency equipment (for example, radios, televisions, computers)
– Small industrial transformers (for example, MRI machines, etc.)
– Small power transformers (for example, battery chargers and inverters)
-Transformers for lighting systems and other low voltage applications (for example, stage lighting)
-Transformers for audio equipment (for example, amplifiers, mixers)
-Transformers for telephone networks (for example, telephones)
-Transformers for car headlamps
Advantages of shell type transformers?
Here are the top reasons why shell type transformers are preferred in their respective application areas;
-Excellent mechanical strength: The shell structure of the transformer is quite strong and robust. This feature alone makes these transformers strong and durable. They are well-protected against external forces and nature.
-High efficiency: The shell structure of the transformer allows it to have high efficiency and achieves an excellent economy. This is due to the fact that the core and shell are essentially one piece of metal, which helps in achieving high efficiency.
-High dielectric strength: The dielectric strength is highly improved in the shell type transformer compared to other types. The reason for this is that there is a large amount of space between the core and the shell in the shell type transformer. This increases the dielectric strength, which helps to reduce or eliminate arcing.
-High heat dissipation: The shell structure of the transformer allows it to dissipate a large amount of heat from its core and thus achieve high efficiency.
-Excellent electrical insulation: The shell structure of the transformer allows it to achieve excellent electrical insulation between its core and its external surroundings. This helps in achieving high efficiency, low loss, and low cost.
Disadvantages of shell type transformer
Common demerits of shell type transformers include;
-Sophisticated construction: Since the shell of the transformer is a complicated structure, it may be difficult to manufacture. This could lead to higher costs.
-Need for special handling: Due to its complex construction, it may need special handling during transportation. This could lead to lower efficiency during transportation and loading/unloading at a customer’s site.
-Difficult to repair: Due to its complicated construction, it may be difficult to repair. This could lead to higher costs.
-Limited heat dissipation: Since the shell of the transformer is a complicated structure, it may not be able to dissipate heat from its core efficiently. This could lead to lower efficiency and higher losses.
Where to buy a shell type transformer?
You should buy shell type transformers from reliable manufacturers and suppliers in China. You can find a wide range of shell type transformers from different manufacturers in China. You can choose a shell type transformer for your application by comparing the cost and quality.
You can use a sourcing agent to locate such manufacturers and suppliers. For instance, ICRFQ is experienced when it comes to electrical components such as shell type transformers for sale.
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