What is Star To Delta Transformation


Star to Delta Transformation is a method of transforming a three-phase electrical network from star (Y) configuration to delta (Δ) configuration. This transformation is commonly used in electrical engineering to simplify the analysis of three-phase circuits. By using this technique, the circuit can be simplified, and its analysis can be done more easily.


The characteristics of star to delta transformation are:

  • It is a method of simplifying the analysis of three-phase circuits.
  • It is based on the principle of equivalence, which states that two circuits are equivalent if they have the same voltage-current relationships.
  • It involves the transformation of a three-phase network from star (Y) configuration to delta (Δ) configuration while maintaining the same electrical characteristics.
  • It is a reversible transformation, meaning that the network can be transformed back to its original configuration.
  • It is used to reduce the impedance seen by the load and thereby reduce the voltage drop across the load.


The construction involves the following steps:

  1. Identify the three-phase network that needs to be transformed.
  2. Draw the circuit diagram for the network in star (Y) configuration.
  3. Apply the transformation rules to convert the network from star to delta configuration.
  4. Draw the new circuit diagram in delta (Δ) configuration.


In a three-phase electrical network, the voltage and current waveforms are out of phase with each other. By using star to delta transformation, the voltage and current relationships can be simplified, making the circuit easier to analyze. The transformation involves the conversion of the network from star (Y) configuration to delta (Δ) configuration by using a set of transformation rules. These rules maintain the same electrical characteristics of the circuit, such as voltage, current, and power.


Star to (Δ) transformation is used in various applications such as:

  • Analysis and design of three-phase motors and generators.
  • Design and analysis of power distribution systems, such as power grids and substations.
  • Control and protection of electrical systems, such as switchgear and protective relays.
  • Design and analysis of electrical transformers, such as step-up and step-down transformers.
  • Analysis and design of electrical circuits, such as power supplies and inverters.

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