star delta connection used in reduce the starting current
at 3 times . how its reduce the current please explian .
Answers were Sorted based on User's Feedback
Answer / raja
At starting times phase voltage is reduced 1/root(3) times
of line voltage.so motor start safely.after reaching 70%of
speed change to delta.now apply fullvoltage
Is This Answer Correct ? | 91 Yes | 19 No |
Answer / subhash sapkal
in star connection winding voltage 1/1.73*line voltage (
there for current is directly prapotional to voltage )
Is This Answer Correct ? | 21 Yes | 8 No |
Answer / kayyum
at start in star 1/root 3 times line vtg, and current is
praportional to vtg.
Is This Answer Correct ? | 10 Yes | 7 No |
Answer / kumar
all of us know in star Vl=1.732Vp & Il=Ip, at start as current is limited to phase current, thats why motor dosent draw more current.and for delta it is normal cond. i.e.415v. get applied across each wdg. insted of 250(as in star) & line current is limited to 1.732 times phase current. Motor remains in str for 4-5 Sec only.Also power consumption in both cases remain same(can be proved).
But it is also possible that motor can draw more current in star position due application of reduced voltage,also the change in such vtg. will affect torque.
If possible try to find out derrivation for vtg. & current in star & delta connected resistance.
Is This Answer Correct ? | 7 Yes | 5 No |
Answer / m.varadarajan
when higher hp motor starts with high current, to reduce
the starting current we are using this connection,it will
reduce 1/root3 times of full load current, after motor
reaches of the rated speed, delta connection applied.this
time full voltage applied to winding and motor run smoothly.
Is This Answer Correct ? | 17 Yes | 23 No |
Answer / hitendra
when motor connect in star connection, motor have high
voltage and reduced line current at starting time. becoz
motor secondery side shorted, and motor torque proponal to
voltage.and motor will start in safe mode.after get the 70
percent speed motor run with permissible voltage and current.
Is This Answer Correct ? | 18 Yes | 38 No |
Ans: in star connection line current is 1.732times of phase
current. while taking the phase current we are reducing the
line current. at the same time phase voltage is equal to
line voltage.
Is This Answer Correct ? | 51 Yes | 108 No |
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