A Wye-Delta connection is used in three-wire transformer applications that need a neutral and secondary load service. The primary side of the transformer is connected to one wire from the power source and the other wire is connected to the center tap of the transformer. The third conductor is used as the neutral.
In two-wire systems, where the voltage is carried on only two conductors, the hot wire comes from the transformer and the neutral is tied to it. If you're not sure if your system is two-or three-wire, check with a qualified electrician. He or she can tell you which type of circuit you have.
The term "Wye connection" refers to a special three-wire configuration used in low-voltage distribution systems. Two conductors from a power line go to a transformer, while the third conductor (neutral) goes back to the main line and connects with all other transformers in the system. This allows for a shared neutral between any two transformers in an array, even if they are wired in opposite phases of AC current.
So yes, a neutral is required on a Wye-connected system to connect all the circuits together.
The most common three-phase transformer connection is the delta-wye connection. The wye-connected secondary distributes single-phase load among the three phases to neutral rather than placing it all on one winding as with a four-wire delta secondary. Because three-phase power is available at each branch circuit, more equipment can be loaded into the same amount of space while still using a wye-connected transformer.
Because delta circuits have only two conductors to deliver current, they require smaller wires and fewer connections within the device receiving the current. Thus, they can fit more closely together in an electrical box. They also tend to draw less power over time than wye circuits because there's not as much resistance between each line conductor and ground. This means that less energy is lost as heat inside your house through these circuits over time!
Delta circuits are used extensively in telecommunications systems where space is at a premium and weight is important. The small size of the cables used with deltas makes them ideal for use inside buildings or under highways where there may not be much room for pulling more stuff out!
Deltas are popular with manufacturers because they're easier to install than wye circuits. With wye circuits, you need to make sure that each wire in the third phase is connected to both a black and a white conductor.
Delta-Wye The most common three-phase transformer connection is the delta-wye connection. A wye-connected load will therefore have three live wires and one ground wire, while a delta-connected load has one live, two hot.
The term "three phase" means that each conductor carries a different phase of current flow. The three conductors are called "phases" because they begin to diverge from one another at some point in time after their origin.
Three transformer coils (windings) are connected in a WYE configuration: The three coils are connected in parallel. The amperage on each line is equal to the amperage on each coil. Each line has the same Phase Voltage between Hot and Neutral. The term "Wye" comes from the fact that these three lines are connected in a wye configuration.
This type of connection is used for polyphase power systems. If any single coil were to fail in a three-coil WYE configuration, the other two would still be able to supply enough current to balance out the system loss so there would be no net loss to the source. A WYE connection provides a way to safely connect multiple units in parallel if they need to be kept separate for some reason. For example, this type of connection can be used when building large arrays of photovoltaic panels or wind turbines. The failure of one unit would not cause a problem for the remaining ones because their Wynes are still balanced.
In general, three-wire delta connections are safer than single-wire circuits because if something goes wrong with one wire or terminal, the other two will still carry current. This means that a circuit breaker need not be tripped when fixing a problem wire or terminal. Single-wire circuits require at least two wires connected to each device or transformer so they can be identified as hot vs. neutral.
A delta arrangement employs just three-phase conductors, whereas wye-connected systems include a fourth neutral wire, which is often grounded but can be left floating. In the wye connection, unlike the delta connection, all three loads are linked at a single neutral point. The advantage of the wye connection is that it reduces the risk of electric shock by preventing any one load from being connected to both sides of the power line.
In a delta system, each conductor carries a voltage only on one side of its connector. Thus, they function as hot wires for delta systems. Neutral conductors cannot carry current so they are always bare copper or aluminum wires in delta systems. If a neutral conductor gets damaged, it must be replaced before you can connect a load to it. This could happen if a rodent chewed through it or if it was hit with a metal object during construction of your house. Otherwise, neutral conductors will usually last for many years without damage; they're just not used for anything important (like lighting) when you're installing a new wiring system.
In a wye system, like the one used in most older homes, all three phases are present on each conductor. Thus, each conductor functions as a hot wire for wye systems. Like with delta systems, neutrals cannot carry current so they are always bare copper or aluminum wires in wye systems.