Answer / nishad

I'm really sorry friends, above answer is wrong!!!!
Just thinK why we are useing STAR/DLLTA starter. if above
the answer is right we may use Delta/star starter.just goes
through the basic of star / delta connection.

In Star >>> Line Voltage = √3 phase voltage

Line Current = Phase current

In Delta>>> Line voltage = Phase voltage

Line current = √3 Phase current

it means when U R connected in delta, it draw more current
as compaire with star connected. as well as in star
connected condition, it carry only 58 % of the line
voltage.due to this reduced voltage current also reduce 1/3
part of delta connected condition.

well, whenever we are connected in delta we will get
good starting torque. that's why.

Answer / dinesh lokhande

Elaborating in furhter to previous answer.

In Delta connection

VL = VPh
VL - Line voltage
Vph - Phase voltage

& IPh = IL / 1.732
IL - Line current
IPh - Phase current

Hence Phase current is less compared to star connection
where line current = phase current.

Answer / praveen

I agree with answer 1&2 and second part of 3rd answer.
while designing an ind: motors(IM) starting method has to
be considered and most simple method is star-delta if you
do not have power system capability for DOL(direct on line
starters)starting. for that you have to design it in delta
configuration.
where i work ,most of the IM's are star connected and are
with DOL starters.Wherever delta connected IM is they all
are designed for star-delta starting.
and of course during its normal operation delta has a
marginal(depending on rating)saving in Cu loss and thus
heat load.

Answer / mukund apte. ( 91 9724397177

If we consider the following
(i) KW of Star motor & Delta motor are same.
(ii) Load on both motors are same.
(iii)rpm of both motors are same.
(iv)PF of both motors are same.
(v) both motors are working at same ambient temp.
(vi)And power supply is without hamonics.
THEN HEATING IN BOTH THE MOTORS WOULD BE EQUAL.
Note:- If power supply contains 3rd harmonics,then Delta connected motor would run hoter.
Practically this has been verified.

Answer / nsreekanth

To get high speed DELTA connection is preferred, since,
Line Voltage = Phase Voltage.

Answer / bob

because the motor power in delta connection more than star connection three times
so if your power source can start up the motor in delta connection (current bigger 3 times of star connection ) you do not have problem.

Answer / s c budhiraja

in delta connected the current in the stater winding is
lesser than star connected winding, resulting in less
heating for the same power

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