What is a 3 Phase Transformer?

A three-phase transformer often represented as a 3 phase or 3ɸ transformer, is made up of three primary coils and three secondary coils. A 3 phase transformer can be built by using three identical single-phase transformers, also known as a bank of three transformers. Another configuration to manufacture a 3 phase transformer is constructing it on a single core.

The operation of a 3 phase transformer is similar to that of single-phase transformers that are commonly used in power plants.

3 Phase Transformer Winding Arrangements

The coils of 3 phase transformers are linked in either a delta or a star arrangement. These arrangements are termed as:

  • Star connection
  • Delta connection

The Star Connection

In a star connection, one terminal from each of the three windings is joined, forming a star or neutral point. This is where the neutral terminal is taken. The second terminal of all windings is taken, and power is supplied to these terminals. This configuration is known as a star connection, Y-connection, or Wye-connection because of its shape.

Delta Connection

The delta connection connects all three windings in series to form a triangle shape. The power is supplied to three junction locations. This setup has the shape of a Delta (∆). As a result, it is referred to as a delta connection or ∆ -connection. This connection is also known as a mesh connection in some instances.

How 3 Phase Transformers are Made

Manufacturing Core

  • Three limb core configuration is taken under consideration to design a 3 phase transformer.
  • Silicon Steel sheets, mainly Cold Rolled Grain Oriented (CRGO), are used to make core sheets that correspond to drawings of the required three-phase transformer coil then these sheets are coated with inorganic insulation.
  • Afterward, mitered joints are employed between the limb and yoke plates.
  • Fiber-glass tape banding is used to keep the core tight and to reduce noise.
  • Corrosion resistant treatment is given to the finished core to protect it from air corrosion.

Manufacturing Windings

  • High Voltage and Low Voltage windings are both made from copper or aluminum. The type of winding used is decided depending upon the amount of current and voltage to be carried. It can be round wire, rectangular strip, foil, layer or cross over.
  • Casting under vacuum is done for making windings. Inserts are provided on the high voltage side to receive tap changing linkages. The connections in windings are insulated by heat shrinkable tubing.

Materials Used

  • Silicone Sheets for making core sheets.
  • Copper and aluminum magnet wire to make primary and secondary windings.

Types of 3 Phase Transformers

General dry type 3 phase transformers include:

3 Phase Isolation Transformers:

3 phase isolation transformers are 3 phase transformers with isolated primary and secondary windings. As a result, the power input will be separated from the power output. Because it can safeguard sensitive equipment, a shielded 3 phase isolation transformer is more efficient than a 3 phase isolation transformer.

Insulation Transformer Applications:

3 phase isolation transformers are commonly used in:

  • Industries
  • Mining organizations
  • Power plants
  • Airports
  • High-rise buildings
  • Subways and other places with high fire safety requirements.

Three-Phase Auto-Transformers

A single coil serves as both the primary and secondary coil in a 3 phase auto-transformer. The leakage flux in these transformers is lower, allowing for better regulation. These transformers also have less copper loss, making them more efficient.

Auto-Transformer Applications:

They are employed in:

  • Induction motor initiation
  • Railways
  • Power transmission and distribution

3 Phase Transformers at Johnson Coil

Johnson Electric Coil Company is best in providing unique single and 3 phase dry isolation transformers that are precisely designed to match customers’ specific requirements. They optimize the performance and features of 3 phase transformers like size, weight, and pricing.

Johnson electric coil company offers 3 phase electric transformers of high quality up to 250kVA in a variety of shapes, sizes, and in bulk quantity. 3 phase autotransformers delivered by Johnson Electric coil have the best efficiency and are cost effective.

Our products are all made in Antigo, WI

Johnson Electric Coil Company provides complete design, engineering, and manufacturing services to supply our customers with the finest, most efficient and cost-effective single phase and three phase autotransformers. Our autotransformer design and manufacturing capabilities are some of the broadest in the industry. We can fully support our customer’s safety agency requirements with expertise in both domestic and foreign agency requirements. In addition to our specialty engineering and manufacturing services, we work with our customers to customize scheduling, packaging, shipping, billing, and communication practices to meet their unique inventory management, product handling, delivery, and customer service needs. Our goal is to provide a level of quality and service that enables our customers to be leaders in their markets. While we mainly sell in the US, our single phase and three phase autotransformers are found all over the world as components in OEM equipment. We pride ourselves on being the only transformer company our customers need.

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