# working of single phase transformer

In this article we will does discussed about working of single phase transformer and also studied abut connection of single phase and pollyphase system

## Working of single phase transformer

In the case of single phase transformers connected to from three phase bank, each transformer is magnetically decoupled from the other. The flows of harmonic currents are decided vy the type of the electrical connection used on the primary and secondary sides. Also, there are three fundamental voltages in the present case each displaced from the other by electrical degree of 120. Because of the symmetry of the A.C wave about the time axis only odd harmonics need to be considered. The harmonics which is triple (multiplies of three) behave in a similar manner as they are co-phrasal or in phase in the three phases.
As against a bank of three single phases transformer connected to three phase mains, In 3-phase shell type transformer generally has the three magnetic circuits that are interacting from each other. The exception to this rule is a 3-phase shell type transformer. In the shell type of construction, even though the three cores are together, they are non-interacting each other. Three limb core type 3-phase transformer is the one in which each phase is magnetically linked with each other. Flux of each limb uses the other two limbs for its return path. This is true for fundamental and non-triple harmonics. The triple harmonics being co-phrasal that cannot use other limbs for the return path (this holds good for zero sequence, unbalanced fundamental magneto motive force also). The flux path is completed through the air so substantially large value of MMF (magneto motive force) produces a low value of harmonic flux in the core remains nearly sinusoidal.
This happens irrespective of the type connection used. The triple order flux sometimes links the tank and produces loss in the same.

In place of this, a three-phase transformer wound on common core offers number of advantage over a bank of single-phase transformers. A three-phase transformer wound on a common core is lighter, smaller and cheaper than the bank of three-phase transformers.  It means it is better than bank of transformer. The common core three-phase transformer also requires much less external wiring than the bank of single phase transformer also requires much less higher efficiency. The bank of three single-phase transformers does offer the advantage of flexibility. In the case of an unbalanced load, one or more transformer in the bank can be replaced by a larger or smaller KVA-rated transformer. In terms of maintenance, a malfunctioning transformer in the bank of transformers can be easily replaced while the entire common core three phase transformers would require replacement.
so it is working of  single phase transformer.

### Poly phase connection of transformer

Because of various advantages of polyphase power during generation, transmission and utilization, polyphase handling  and operations are very important. From the poin techno-economic considerations, no single connection or setup is satisfactory for all applications and of various forms. Star and mesh connections are very commonly used forms. Apart from these,vee or open delta connections, zig-zig connections, T connections auto transformer connections, multi winding transformer etc.