Answer / girish

B'coz Form Factor of AC Sine Wave is 1.1 so Transmission
Voltages will always be the integral multiples of 11

for eg. 220, 440, 660, 1100, 3300, 6600, 11000, 33000,
66000, 110000

Form Factor = RMS Value of Sine Wave / Average Value of Sine
Wave

RMS Value = 0.707
Average Value = 0.683

0.707 / 0.683 = 1.1

Answer / anirban dasgupta

The real reason is not form factor. Because now 400kv, 765kv, 1200kv(yet to be commissioned) are transmitted. 
The real reason is actually due to a misnomer that started in the olden days. According to them, some voltage was always lost and they accounted it to be 10% of the transmitted voltage. So they always transmitted voltages 10% above what they required. For example if they wanted to transmit 100kv, they used to transmit 110kv, similarly 200kv - 220kv; 10% higher than what is actually required. That is why this multiple of 11 was there.
But now a days with advance protection schemes, people are transmitting voltages of the order 400kv, 765kv etc

Answer / engineered

whosoever asked this question first note that,

Transmission line voltages ranges from
33kV, 66kV, 132kV, 220kV, 440kV

& not 110V, 220V, 33kVA, 11kVA...........

& Form factor is the ratio of RMS/Average value which
equals 1.11

if we consider 10kV, then the voltage should come 11111V
but the case is we get 11000V.
Think on it guys, 11kV has nothing to do with form factor.

Answer / remo

To maintain foem factor voltage transmission is always in a
multiple of 11.
ex-
Form Factor = RMS Value of Sine Wave / Average Value of Sine
Wave

RMS Value = 0.707
Average Value = 0.683

0.707 / 0.683 = 1.1

Answer / prabhat kapoor

b'coz in transformer,the form factor value is multiple of 1.1.that's the reason.so it is always in multiple of 11.

Answer / rachel

Still i can't understand what the people actually saying about the form factor...so what if form factor is 1.11?it just an ratio that relates both rms and avg values....and we have learnt that whatever voltage that we are transmitting it is only rms so how avg value comes in picture?someone pls correct... 

Answer / psingla

It's bcoz of form factor which is.
rms value/AVG.value both values are considered bcoz we can get both half & full cycle of AC current
RMS value=0.707 of max. Value of current transmitted
AVG.value=0.637 of max value of AC current transmitted

Answer / saket

rather than a technical basis for the values being multiple of 11 it is evolutionary basis.. the initial electrical equipments(bulb)were rated 100v.. and supply generated was 110 v to account for transmission drops. soon ac came and replaced the system with 110v ac generation which evolved with time to generate and transit at even higher multiples eventually coming down to 110 v.. so multiple of 11 continues.

Answer / jalapathi

in india standard generated voltage is 11kv. so what ever
be the ratio of transformer 1,2,3... it should be multiple
of 11.

Answer / ajay

no any specific reason of this question.

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