If a motor of 8.5 KW with same load and using in both Star
& Delta one by one,then which will take more current in
star connected or in delta connected

Answer Posted / subash nishad

take line voltage is VL and Zs is the impedence of
each phase,
then in case of delta connection ,VP=VL

phase current I(delta)= VL/Zs

we know that in delta connection ,
Line current IL= root 3 times phase
current
so line current I(delta)=root3*VL/Zs
in case of star connection,Vp= VL/root3
phase current I(star)= VL/root3*Zs
weknow that in star connection,
phase current=line current
IL(star)=VL/root3*Zs

so, IL(delta)/IL(star)= root3*VL VL
---------- / ----------
Zs root3*Zs


= root3 *VL root3*Zs
--------- * ----------
Zs VL

= 3

IL(delta) =3*IL(star)

hence, delta connection will take 3 times more current
than star connection..

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