What is the difference between 'star' and 'delta' connections in a three-phase electrical system?

The key difference between star (also known as wye) and delta connections in a three-phase electrical system lies in how the three-phase windings are interconnected and the relationship between the line voltage, phase voltage, line current, and phase current. In a star connection, one end of each of the three windings is connected to a common point, called the neutral point or star point. The other ends of the windings are connected to the three lines. The voltage between any two lines (line voltage) is √3 (approximately 1.732) times the voltage across each winding (phase voltage). The current flowing in each line (line current) is equal to the current flowing in each winding (phase current). A star connection allows for the use of a neutral wire, which provides a return path for unbalanced currents and enables the supply of single-phase loads. In a delta connection, the three windings are connected in a closed loop, forming a triangle. The lines are connected to the three corners of the triangle. The voltage between any two lines (line voltage) is equal to the voltage across each winding (phase voltage). The current flowing in each line (line current) is √3 times the current flowing in each winding (phase current). A delta connection does not have a neutral point and is typically used for three-phase loads only. Delta connections are generally used for high-power applications, while star connections are often used for distribution systems where both three-phase and single-phase loads are supplied.