Answer / amjith meeras

in three phase system we can use it in two modes one is delta connection and other is star connection,
in delta connection we will get only phase to phase voltage, in india its 415vtg its because of there was no neutral point in delta connection.
but in star connected it has one neutral point and 3phases in R-Y-B sequence so we will get phase to neutral voltage and phase to phase voltage from it.
for ex: the transformer primary was connected with 3phase 3core cable but its secondary side has one neutral and three phase it connected with 4core cable.
all machine other than motor wants neutral for it work.

Answer / naveen kumar k s

in single phase system in our india 230v &three phase
system 415V BECAUSE IN *SINGLE PHASE WE CAN USE NEUTRAL
POINT THIS IS THE RETURN PATH OF THE CURRENT *THREE PHASE
SYSTEM R-Y-B WE CAN MEASUre THE Vg Wrt R-Y
Y-B
B-Y BUT ANY WAY WE
CAN'T MEASURE WITH NEUTRALL(IN 3Ph IT SHOULD REEQUIRE TO
SHOWS 460Vg BUT IT CAN'T SHOW BECAUSE RMS VALUE OF AC)
THAT'S WHY THE RMS VALUE OF P-N Vg & P-P Vg IS DIFFERENT
BECAUSSE OF THIS REASON OUR MEASURING Vg DIFFERENT

Answer / ram43

three phase (RYB)-- 415 voltage
single phase (PN)---- 230 voltage used...

Answer / arikrishnan

three phase system;
we can get tow types of voltage single phase and 3 phase.three phase motor has self starting.it has constant torque.fault finding is very easy.efficiency is high. we can get large capacity of the motor.it's output is high. transmission cost is low.three phase alternator parallel operation is easy.
single phase system;
we can get only one type of voltage.it has no self starting.it's torque is variable.fault finding is difficult. efficiency is low.we can get only low capacity motor only 1/4,1/2,1,1.5hp. its out put is low. transmission cost is high.we can't parallel with single phase alternator.

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