Electrical World

                                                                               The transformer is said to be in parallel operation when their primary windings are connected to a common voltage supply and the secondary windings are connected to a common load. Advantages of Parallel Operation     It increases the reliability of supply system.  The size of transformer increases with the increase of its rating,its transportation and instalation is difficult.On the other hand transportation and instalation of small size transformers are easy. One ore more transformers may be taken under maintenance and the remaining will supply the load.  Disadvantages of Parallel Operation   Increasing short circuit current that increase breaker capacity. Bus rat...

Basic Principle                Ac generators or alternators operate on the principles of electromagnetic induction. There is one important difference between A.C generator and D.C generator the armature rotates and the field system is stationary where as in A.C generator it is just the reverse of it.In their case standard construction consists of armature winding mounted on a stationary element called stator and field winding on a rotating element called rotor. Speed and Frequency           In an alternator there exists a definite relationship between the rotational speed (N) of the rotor the frequency (f) of the generated e.m.f and the number of poles P. P= 120f / N        It is clear from the above equation that because of slow relative speeds of engine driven alternators their number of poles is must greater as compared to that of the turbo generators which run at very high ...