Why Are 3-Phase Transformers Beneficial Over Multiple Single-Phase?

Three-phase systems are very rare as compared to single-phase systems, but they are actually more economical. Multiple single-phase transformers can be grouped together to provide power between three-phase systems in different configurations. But, if three-phase transformers are used instead, the same performance can be brought about with lesser material requirement, lesser size and lesser weight.  Thus, it is because three-phase transformers use lesser material to transmit same amount of electrical power that they are proved to be more economical.


Difference between single phase and three phase

In single phase circuits, there is only a single phase, wherein current flows only through a single wire with a single return path running to complete the circuit. These single-phase systems have been used since ages. However, with the invention of the three-phase where more than one phase can be used to generate and transmit current, things have changed. In three-phase systems, three phases are sent together from generator to load, with each phase having a 120° angle difference electrically. Single-phase power supplies use two conductors – phase and neutral. When compared to three-phase supplies with no neutral and same phase-to-ground voltage and current, the three-phase transmits three times as much power using only 1.5 times as many wires.

Construction of three-phase transformers

Three-phase power transformers are composed of 3 single-phase transformers wound around a core, which are then placed inside a case filled with insulating oil that provides electrical insulation between the windings and enclosure. This prevents formation of moisture, thus reducing the possibilities of deterioration of winding insulation. Such three-phase transformers are used throughout the industry to change values of three-phase voltage and current to desired units.

Three primary windings of three single-phase transformers are connected to one another and three secondary windings are connected internally in a fixed configuration to get a three-phase supply. These windings are connected in either Δ or Y configurations to form a complete unit. This is because Δ connections enjoy higher levels of reliability and Y connections provide chances for multiple voltages. The various combination options may be Y – Y or Y – Δ or Δ – Y or Δ – Δ. These connections must be perfect or else it can damage the equipment and cause injuries too.

What makes three-phase transformers desirable?

There are certain unique properties of three-phase supplies that have made them so advantageous and preferred in power distribution systems today. First of all, there is constant power transfer that helps in reducing motor and generator vibrations. Also, the rotating magnetic field produced is of constant magnitude, thus simplifying the design of electric motors. Moreover, the conductor required in a three phase is 75% that of a conductor required in single phase; the net power from all phases providing continuous power to the load. With all these benefits, if you are looking for such a device too, you must get in touch with Miracle Electronics, the most renowned three phase transformer manufacturer in India, who manufactures the finest quality transformers in accordance with international standards for fault-free generation, transmission and distribution.


Three phase transformers are constructed by combining the primary and secondary windings of three single-phase transformers in a fixed configuration to get a three-phase supply. These transformers are much better as compared to three individual single-phase transformers.


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