A delta electrical connection is formed when three branches of the electrical network are connected to form a closed loop, whereas a star electrical connection is formed when either terminal of three branches is connected to a common point. Star electrical connections can be converted into delta electrical connections and vice versa.
Star and delta forms are the most common ways of connecting three branches in an electrical network. When the three branches of an electrical network are connected from nose to tail, they form a closed loop that resembles a triangle. This closed triangular loop is known as a delta connection.
When either terminal of the three electrical networks is connected to a common point, they form a Y pattern of electric connection. This Y pattern is known as a star connection. According to Electrical Technology, the common point of a star connection is called the neutral point or star point. No neutral point is present in a delta connection.
A star connection is a 3-phase, 4-wire system, whereas a delta connection is a 3-phase, 3-wire system. Low insulation is required for star connections, whereas high insulation is required for delta connections. Both star and delta forms of electrical connections can be transformed from one form to another.