Answer / yousef madhi

Suppose That the line voltage on DELTA connection
V(line)= V
and the line current I(line)= I

as we know in DELTA connection the phase voltage equal the line voltage and the phase current equal to the line current times 1/root(3)

then V(phase)=V(line) = V
and I(phase)=I(line)/root(3) = I/root(3)





In STAR connection if again the line voltage equal to V(line)= V , the phase voltage will equal to line voltage time 1/root(3)

V(phase)=V(line)/root(3) = V/root(3)

and as per Ohm's Law (V=I*Z) and in both connection (star & Delta) we have the same winding impedance, any change in Voltage will change the current in the same amount.

so the phase current for star connection will be equal to

I(phase-star)= I(phase-delta)/root(3)
=(I/root(3))/root(3)
= I/3

and as we know in star connection the line current equal to the phase current

I(line)=I(phase)= I/3





Conclusion:

the line current in star connection is reduced by 1/3 time the line current in delta connection

Answer / vknt

in star connected winding net resistance across the line
voltage will be less as the winding across line volt are in
series.

in delta connected winding the net resistance across the
line voltage will be more as the winding across line volt
are in parallel. (one winding will be in parallel with
series combination of other two. so net resistance is less
than the resistance of one winding in delta)

Answer / vijay maurya

According to ratio line V equal to phase V upon root 3 . So
that decrease the V, decrease the current

Answer / sibi mathew

When motor is started there is no power. the only factors which effects the current is the impedance of the winging.
i.e. the current I=V/Z. So since the phase voltage in star connection =phase voltage xroot3,starting current is reduced to one third of delta connection.

Answer / abhishek goyal

STAR : decrease the voltage
decrease the torque
decrease the speed
decrease the current
as per electrical formula

Answer / kalidass

Initially there is no back emf in motor while starting. If
apply high voltage the motor will draw more current. That
is why the motor always satat with star connection.(low
voltage )

PLC Training in chennai | PLC Training institute in chennai, PLC Training center in chennai | Best PLC Training in chennai | PLC Training course in chennai | SCADA Training in chennai | PLC Training in india

1 Answers   Exide,

Suppose the incoming power is 11 kw, but the load require only 8 kw means how can we save or use the excess power?

3 Answers  

One 200 V, 100 W bulb is connected in series with primary of a 200 V, 10 kVA transformer. If its secondary is kept open circuited, then the bulb would have (1) Full brightness (2) Poor brightness (3) A little less than full brightness (4) More than full brightness...explain

2 Answers  

What are the different parts of Alternator and how it works?

1 Answers  

design of IGBT firing circuit for 11KV

0 Answers  

i have one transformer 1000kva, 11/.433kv. we are using 200/5 amp. ct unit for measuring purpose, & one 800 amp. V.C.B Unit for the same t/f operate, i wants to known the primary current of T/F is only 53 amp. why we used 800 amp. V.C.B ? & 200/5 amp. CT Unit.

4 Answers  

How to calculate 5hp 415v 3phase 2800rpm Ac motor full load current with out tourgh

1 Answers   Siemens, Spatel,

what is split phase ac system?

3 Answers   AMIE,

what will happen power cables laid without gap in underground

1 Answers  

what is meant by crawling??

10 Answers  

What will hapen if we connect more capacitors than required for powerfactor control? Exactly what will be the effect on power system?

2 Answers   Mandovi Pellets,

why ct secondary side shortlink provided? its open what will happen?while running ?

2 Answers   Essar,