Types of Transformer

Air-core transformers are designed to transfer radio-frequency currents—i.e., used in radio transmitter and communication devices etc. As the name suggests, these transformers have no solid core, which makes them very light in weight, thus making them ideal for small-sized portable electronic devices. Air core transformers create flux using the windings and the air passing through them. This help air core transformer to completely eliminate undesirable characteristics of ferromagnetic core (eddy current losses, hysteresis, saturation, etc.)

Advantages:

• Zero distortion.
• Zero dissipation of signal quality.
• Noise-free operation.
• Lack of losses in hysteresis and eddy currents.
• Lighter in weight.

Limitations:

• Low degree of coupling (mutual inductance)
• Unsuitable for use in power distribution.

In this type of transformer, primary and secondary windings are wounded on multiple iron plates. These iron plates provide perfect linkage path to the generated flux and serve analogous functions in the audio-frequency range. Iron core transformer are widely used and highly efficient as compare to air core transformer.

Advantages:

• Handle large loads at a low frequency.
• Offers less reluctance.
• Highly efficient.

Limitations:

• Large eddy current losses

Ferrite core transformer means a transformer whose magnetic core is made up of ferrite. Ferrites are non-conductive, ceramic compounds that are ferromagnetic in nature. The high magnetic permeability of these transformers makes them ideal for a variety of high frequency transformers, adjustable inductors, wide band transformers, common Mode Chokes, switched-mode power supply and radio frequency applications.

Advantages:

• Low reluctance magnetic path.
• High current resistivity.
• Provides low eddy current losses over many frequencies.
• High magnetic permeability, coercivity and Q-values.
• Low hysteresis factor, DC sensitivity and signal distortion.

Limitations:

• Easily saturated (its saturation flux density is typically < 0.5 T).
• Permeability drifts with temperature.

3. Based on Usage

Main principle of power transformer is to convert the Low voltage input to a high voltage output. This transformer acts as a bridge between the power generator and the primary distribution grid. This has complex construction due to high power generation and mainly installed at the generating stations and transmission substations. The power transformers are employed in the transmission networks of higher voltages.

Advantages:

• Suitable for high voltage applications (greater than 33KV).
• High insulation level.
• Minimize the power loss.
• Cost effective.

Limitations:

• Loaded for 24 hours at transmission station, thus, the core and copper loss will occur for the whole day.
• Big in size.

Distribution transformers are step down transformer and used in distribution network for industrial and domestic purpose. These transformers convert High grid voltage to the end customer required voltage where the electrical energy is distributed and utilized at the consumer end. In order to distribute the power from power plant to remote locations, these transformers are used.

Advantages:

• Small size.
• Easy installation.
• Low magnetic losses.
• It is not always fully loaded.

Limitations:

• Designed for 50-70% efficiency.
• Low flux density as compare to power transformer.
• Regular load fluctuations.
• Time-dependent.

4. Based on Electrical Supply

On the basis of configuration, transformer types are listed below.

• Single phase transformer
• Three phase transformer

When there is only one coil at primary side and one coil at secondary side, then the transformer is called single phase transformer. Here the power supplies through a single conductor. This type of transformer accepts single-phase alternating current and output single-phase alternating current, typically at variant voltage level that operates in a unified time phase. These types of transformer are mostly used in the household devices.

Advantages:

• Simple network.
• Cost effective.
• Most efficient AC power supply for up to 1000 watts.

Limitations:

Three phase transformer means the power flows through three conductors. Three phase transformer contains six coils, three coils at primary side and three coils at secondary side. This type of transformer accepts three-phase alternating current and output three-phase alternating current, typically at variant voltage level that operates in a unified time phase. These types of transformer are mostly used as a power or distribution transformers  

Advantages:

• Large motors or heavy loads materials.
• Transmission of power to long distance through magnetic field.
• Maximum power transfer capability.
• Power failures do not occur. 

Limitations:

• Required many cooling systems depending on the transformer rated power.
• Complex network.

5. Based on Place of Usage

On the basis of place of usage, transformer types are listed below.

• Indoor Transformers
• Outdoor Transformers

Indoor transformers are usually a Dry type transformer. These transformers use air as cooling medium and usually their primary and secondary side connections are isolated. Dry type transformers are installed in buildings and close to buildings because they are environmentally safer i.e. less flammable. These type of transformers are considered as ideal for shopping malls, hospitals, residential complexes and other commercial areas.

Advantages:

• Low maintenance cost.
• Safer option as compare to oil-filled transformer.

Limitations:

• Higher operating loss.
• Noise pollution.
• Expensive.

Outdoor transformers are usually an Oil filled transformers. These transformers use oil as cooling medium and are designed to be utilized in outdoor environments due to the chance of oil leakage and spills that create a fireplace risk, and must be protected against environmental conditions.

Advantages: 

Limitations:

• High Maintenance cost.
• Require periodic sampling of the oil.