Delta vs WYE 3-Phase EMI Filters

Three-phase systems can be configured in two different ways to maintain equal loads; these are known as Delta and WYE configurations. The “Delta” and “WYE” names are specific indicators to the shapes that the wires resemble once connected to each other. “Delta” comes from the Greek symbol “Δ”, while “WYE” resembles the letter “Y” and is also known as the “star” circuit. Both, Delta and WYE configurations have the flexibility to deliver power over three wires, but the principal differences between the two are based on the number of wires available within each configuration and the current flow. The WYE configuration has gained popularity in recent years because it carries a neutral wire that allows both line-to-neutral (single-phase) and line-to-line (2/3 phase) connections.

Delta 3-Phase EMI Filters are designed to reduce the electromagnetic interference in devices connected to 3-phase delta power. The Delta configuration contains four wires; three hot conductors and one ground conductor. The phase loads (such as motor windings) are connected to each other in the shape of a triangle, where the connection is made from one end of winding to the starting end of the other, forming a closed circuit.

WYE EMI Filters are designed to filter typical switch mode power conversion devices and other applications that require a neutral connection. This configuration is composed of five wires; three hot conductors, a neutral and a ground. In WYE configuration, the phase loads are connected at a single (neutral) point where the neutral wire gets connected.