Power Analysis

. A.C Genetrators work on electromagnetic induction principle.Alternators have Armature as stator and field as rotor. Alternators are generating power in power system when they are connected in parallel with many other alternators.Often the electrical system to which the alternator Is connected has already so many alternators and loads connected to it no matter what Power is delivered by incoming alternator the voltage and frequency of the system remain constant.In that alternator is said to be synchronized with infinite bus bars . E1 and E2 are in phase relative to the external circuit and phase opposition to the local circuit. If speed of incoming machine is not brought to that of machine1 then their frequencies are different and phase differences between their voltages are different.Sometimes the resultant voltage is maximum and other times minimum.Due to changing current through the lamps a flickr is produced and frequency of flickr is f2-f1.Lamps will dark up and glow up alternatively.Dark indicates the two voltages are in exact phase opposition to the local circuit.Synchronisation is done at the middle of dark period.some engineers prefer ‘lamp bright ‘ method because lamps are much more sensitive in changes in voltages at maximum brightness.

. In 3 phase alternators it is necessary to synchronise one phase only and the other 2 phases will be synchronoised automatically.It is necessary that incoming alternator is phased out i.e the phases are connected in proper order R,Y,B .If the incoming machine is running faster or slower the lamps will light up alternatively .synchronisation is done when lamp in phase A is dim and lamps in phases Y and B are equally bright..This method is ‘two bright and one dark’ Synchronizing power in three phases =3 E^2/XS I1=(E1-V)/Z

I2=(E2-V)/Z

Power is maximum when power factor is unity and Xs