Why we are
using High Voltage AC supply..?
Most our
consumer gadgets are using DC supply like TV,Computer,Laptop etc.,then why we
are using AC ?
Because the AC supply voltage only we can
efficiently and easily stepup or stepdown. We can also stepup or stepdown the
DC with the help of modern power electronics devices,but it is complicate and
not much efficient.You all know the transformer is the most efficient machine
in electrical(more than 90%).
Again the question is why stepup or
stepdown the voltage? We can find the answer from the following formula.
We know power P=V*I
Replace ‘V’ with ‘IR’(ohm’s
law)
Power P=I2R
This power
equation shows where ever a resistance present it will consume some power as I2R and
it proportional to the square of the current.
We know our current carrying conductor
has some resistance and they will sure consume the electric power. We don’t
need the conductor to consume the power actually it just waste the power.Our
requirement is to use the power only by the equipment. To avoid this problem we
need to reduce the current!
Only way to minimize the current
without changing the power requirement is to stepup the voltage of the supply
through a transformer.
The following practical example will
clear the whole concept.
Imagine you
have a small factory 50KM away from an electric substation and you need 1000KVA of total power.
Case 1:
You are going to take that without stepup
the voltage, so V=230V
Power P=VI We
know P=1000KVA,V=230V
Current I=1000KVA/230V=4347.82A
Case 2:
You are
going stepup the voltage and transmit,so
V=11KV
Power P=VI We
know P=1000KVA,V=11KV
Current I=1000KVA/11KV=90.909A
From the
case 1 and 2 we can see that higher the voltage lower the current. Advantages
are
1. Less current so less the losses.
2. Need Small Conductor because less
current.
Only
Disadvantage is we need two transformer
and suitable insulation.But it is negligible when we account this for a long
time of operation.
Really good bro..so simple
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