7.	Describe delta-Y and Y-Y connections.
a.	Delta-Y is a mesh connection for connecting electrical apparatus to a three-phase circuit, the three corners of the delta as represented being connected to the three wires of the supply circuit. A delta contains three phases that are tied together but needs no neutral wire as each of them serves as a return path to complete the circuit back to the generator.
b.	Y-Y connection is a method of connecting the ends of the windings of a poly-phase transformer; each of the three windings are joined at a common point; the other ends of the windings provide the line-to-line voltages.