Three Phase A.C. Supply

Three Phase A.C. Supply

one phase A.C. Supply:
                                        In one phase AC. Generator these is a coll with a pair of slip rings.An alternating voltage is generated across the slip rings when the coll rotates in a magnetic field.

Three Phase A.C. Supply:
                                                                  In a three phase AC. generator three are three colls inclined a 120 to each other,each connected to its own pair of clip rings three alternating voltages are generated across its own pair of clip rings when this combination of three colls rotate in the
 magnetic fields.
Explanation:
                                The phase difference between these voltages is 120.

1. When voltage across the first pair of clip rings it will have a phase of 0.
2. Then voltage across the second pair of clip rings would not be zero but it will have
a phase of 120.
3. similarly at this instant the voltage generated across the third pair will have a phase
of 240.
This is shown in figure has four terminal A,B,C and D. The starting point of all the three
colls has common juntion D, which is earthed to the shaft of the generater and the other
three ends of the coll are connected to three ends of the colls are connected to three
separate terminal 9A,B and C) on the machine. The voltage across each of lines connected
to terminal A,B,c and the neutral line is 230V.Because of 120 phase shift voltage across
any two lines is about 400V.
Advantages
                              The man advantages of a three phase supply is that the total load is divided in three parts so that none of the line is over loaded. Ifheavy load (consisting of a number of air conditions
and motors etc.) is supplied power from a single phase supply,its voltage is likely to drop at
full load.
. The three phase supply gives 400V which can be used to operate some special appliances that
require 400V for their working.