The leakage reactance is one of the components of the reactance in the input impedance that is there when the load impedance is purely resistive.
The leakage reactance is due to flux that fails to link both the primary and the secondary windings.
This depends on the voltage, and whether it is a three phase or single phase transformer.
The overall reactance of the armature winding is the sum of its leakage reactance plus fictitious reactance, which is known as synchronous reactance (Xs).Xs=XL+Xarwhere XL and Xar are in Ω/phase. Therefore, Xs is in Ω/phase.The impedance of armature winding is obtained by combining its resistance and its synchronous reactance.
By having a transformer with 3 phase input and single phase out put
Synchronous Reactance (in a generator analysis domain) is and equivalent series per-phase inductance term (think per-phase winding resistance) and is mainly composed of the machine's per-phase leakage inductance (equivalent series inductance of primary and secondary flux leakage) and armature reaction (distortion in flux introduced by an armature current in a machine, once again on a per-phase basis; described as a series inductance). L_SyncReac=L_leakage+L_ArmatureReaction. That sort of touches the surface of synchronous reactance.
Harmonics are really not needed in single phase transformers.
Your question is rather vague. If you are asking what do you call a group of single-phase transformers, connected to supply three phase, then the answer is a 'three-phase transformer bank'.
It'll behave like a transformer on open circuit with a huge leakage reactance due to the very large air gap resulting from there being not rotor. So it will draw a largish reactive current from the supply.
A single-phase transformer works with a single-phase supply, while a 3-phase transformer is used with a 3-phase supply. A single-phase transformer has 2 wires on the primary and secondary (ignoring taps) while a 3-phase tansformer has 3 or 4 wires on the primary and secondary.
By design are you going to wind the transformer yourself? In your design you need a 5:1 ratio. On the output side of the transformer any two legs of a three phase transformer is considered single phase voltage. Good luck on your project.
The phase shift is caused by inductance in the transformer. Any inductance from magnetic flux that fails to link both windings is called leakage flux, and the resulting inductance is called leakage inductance.
to determine the transformer characteristics...
A three-phase transformer bank is often used in power stations because it is easier to construct and transport very large single-phase transformers, compared with constructing and transforming an equivalent-capacity three-phase transformer.