in star connection
line voltage is=(3)^(1/2)*phasevoltage
line current is=phase current
in delta connection
line voltage is =phase voltage
line current is =(3)^(1/2)*phase current

power ratio=( ((3)^(1/2)*phasevoltage*phase current)/((((3)^
(1/2)*phasevoltage*phase current))
so power ratio is =1.

Power ratio between star and delta is 1:1
because power in star=line voltage(3^1/2*Vph)*line current
(Iph)=3^1/2VphIph
power in delta =line voltage(Vph)*line current(3^1/2*Iph)
=3^1/2VphIph

If placing 3 resistors in Delta rather than Star will end
up with 3 times more heating power. This is because you
have sq root of 3 times more voltage across each resistor
in Delta and hence end up with the sq root of 3 times more
current through each resistor. The sq root of 3 of more
voltage times the sq root of 3 of more current than, star
connected resistors means 3 times more power. Capacitor
are often connected in Delta for power factor correction as
this offers 3 times more reactive power than in Star
connection, though be aware they need to be able to cope
with line voltage across each Cap in Delta.

i think transformer just step up or step down voltage or
current only but power remains same(constant).so ratio of
p1 to p2 is 1 when same transformer connected in star or
delta.

The power transformation ratio in the transformer is
1:1.Only the voltage and currents are subjected to
change.Pri MVA=Secondary MVA. Except to compensate for some
losses.

If placing 3 resistors in Delta rather than Star will end
up with 3 times more heating power. This is because you
have sq root of 3 times more voltage across each resistor
in Delta and hence end up with the sq root of 3 times more
current through each resistor. The sq root of 3 of more
voltage times the sq root of 3 of more current than, star
connected resistors means 3 times more power. Capacitor
are often connected in Delta for power factor correction as
this offers 3 times more reactive power than in Star
connection, though be aware they need to be able to cope
with line voltage across each Cap in Delta.
Thanks

IIly in star connected vphase=Vline/rt3,
Iline=Iphase
ie Power = rt3 vpahseIphaseCos
ie. in both star and delta power remain same
therefore the Power ratio = 1.

Three set (each phase contain 2 cable of 400 mmsq CU XLPE
AWA) of single core cables are connected to 11 KV motor of
14 MW & the switch gear supplay is taken from 11kv feeder &
this supplay taken from 275 KV substation. Problem is one
pair cable(L3- 2 cable ) getting very hot & gland melted
and damaged in switch gear side. the other two cable
haven't any more hot(ambient temp only & L3 haveing 95- 100
Degree C. The same problem happened in 275 KV substation
switch gear side also where the supply taken for 11 kv
switch gear. But here L2 phese cable had problem. Why it is
happening like this?. The cable having temperature
different at different location from gland side inthe case
of 11KV feeder of 275 kv substation. why ?

It is observed that AVR of an Alternator is more likely to
fail if the Generator and Mains Neutral are directly
connected to each other. Why should this be so?

in power station what is the electrical circuit length of
spacing between power transformer and lightning
arrestors,for the voltage system of
230kv,110kv,33kv,22kv,11kv?

i want to ask that as everybody knows that in star
connection on star point is called neutral. my question is
that why on that poin called neutral. what is the reason
behind it. what is the logic behind it. i heared somewhere
that on this point all phases current become zero thats
why. if this answer is right then prove why on that point
is current become zero. if this answer is not right then
tell me the right answer. post ur answer here or on my mail
address. m.ikram786@yahoo.com
m.ikram555@gmail.com.
thanks.