Answer / l.veeraragavan

because compared to other phases(4,5..) the three phase
power production is more economic.

Answer / haroon

becoz there is 360 degree in a circle and we can have dived
it in 3 equal parts i-e 120degree.the meximum power that we
can generate on in three phase system, let draw a sine wave
of three phase supply when R is on its peak the Y is
behined it by 120 and the blue is bhined R bye270 dgin this
wave 2 phase r +ve at the same time which is needed for
motor rotating which can be +ve if we draw sine wave of 5
or 4 phase generator
haroon_et@yahoo.com

Answer / francis

Hi, sukhvinder

R U AN ELECTRICAL ENGINEER OR A LAYMEN,

DONT PLAY GAMES WITH THE PEOPLE WHO R ASKING ANSWERS TO THE
QUESTION

Answer / karthik

it is not that we cannot generate 4 phase voltage. if that
is the case the phase difference will 90(360/no of phase).
so the voltage b/w phase 1&3 will be 2*nominal voltage but
between 1&2 it will not be like that. so it is not in use.

Answer / zaheer ahmad

IT is more economic to use three phase as compared to 4 or
more phases .

Answer / silu

cost of transmission,losses,number of insulater,tfr size are
increases.

Answer / eduardo

You are wrong. We can generate power in 4 or 5 phase or more
or even 2 or 1 phase. The reason we generate only 3 phase is
we don´t need 6 wire (1 to go and 1 to back) to carry the
power. We only need 3 wires. This is because if they are 3
and have 120º phase difference, and if the load in all the 3
phases is equal, the sum of the 3 return current is zero. So
we don´t need wires to "carry back" the current. This is
very economic, and are used in all the world.
There are several articles about it in the net. Try search
neutral current.

Answer / sudhir

for 4 phase system ,phase difference b/w phase 0,90,180,270
deg.at every instant 0deg phase cancil by 180 deg phase,and
90deg phase cancil with 270 deg phase . and two conductor
work as phase and two for return path so it work as two
circuits of two phase supply and there are lot of advantages
of three phase supply over two phase supply.if we need of
two phases then it is simply generated by three phase.
and three phase system is symmetrical(line voltage or
current in magnitude between any two phases is equal to
other two phases in balance condition ) but 5 phase circuit
is not symmetrical.so calculation and operation is difficult.
as we increases the phases the fluctuation of torque in case
of polyphase induction motor is reduses.so 6-phase motor is
bater then 5-phases motor and 6 phase supply
simply can obtains by 3 phase supply so why we generate 5 phase
supply.

Answer / umesh

Hi

we are generating three phase supply system because three
phase system is a balanced type of system. Angle difference
between the three phase is 120 degree which is balancing
the system and we are getting neutral at star point for 230
volt equipment.

Answer / sudhir

for 4 phase system ,phase difference b/w phase 0,90,180,270
deg.at every instant 0deg phase cancil by 180 deg phase,and
90deg phase cancil with 270 deg phase so resultant voltage
at everyinstant wiil 0.

Please tell me the earthing procedures adopted for the STAR-STAR 3 Phase transformer in india and give a better sugession for earthing

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