Answer / divyaprabha.b

In India the generating voltage is 11kv.b,coz we,all know
the formfactor value is 1.11.due to this the power is
generated in 11kv & transmitted as multiples of 1.11

Answer / raman jain

I am not convinced with the fact that due to form factor
1.11 generated voltages in India is multiples of 11 kV. If
it is so why we use 400 kV and not 440 kV , even we are
going for 765kV which is also not the multiple of 11.

Why only Indians consider the form factor for deciding the
generating voltage level? Why western countries are not
bothering about this form factor.

In my opinion it is just co-incidence.

Answer / ashish

In Electrical Generation plants, the generation voltage will
be in the range between 11kV and 33kV. Generator designers
wishes to generate the electricity at high voltages as
possible to limit the stator current required to achieve the
desired output. But certain technical and economical
problems will arise which results in designing the generator
for particular voltage and current ratings.
• Low voltage generation for particular power level (say
500MW) requires large size of the stator conductors as huge
currents flow through the stator because of low voltage. (
Any current carrying conductor size is decided by the amount
of current flowing through the conductors). Thereby increase
in the cost and size of the machine takes place.
• On the other hand, increase of the machine voltage
significantly beyond the minimum necessary value results in
more insulation required on the generator stator windings,
thus increasing its size and cost.
Therefore an optimum value of Voltage and Current values are
attained for designing the generator considering the cost
and size factors of the generator.
Example:
660 MW generation plant usually operate at 23.5 kV with line
currents of about 19 000 A at 0.85 power factor.

Answer / zahid noor

It is only form factor which has a constant of K= 1.11, &
if I can recall the old formula which says Induced
EMF/Voltage in a Transformer was 4.44 phixBxNxA volts,&
hence the voltage ranges for transmission are in the
multiples of 1.11. Regarding other answers of Insulators,
there is no point regarding this & power is being
transmitted through cables also where you need not require
insulators.

Answer / johince

Multiples of 11 has no role decoded from form factor and anything
like that (I believe). the relation to form factor is just a
coincidence.
In early days when technology has not advanced this much, the
transmission lines consumes around 10% of the total power
transferred. Normally loads are designed as multiples of 10 or
100 KW. So the generation done for required load power +
transmission loss. ie 11KW, 110KW etc. So generated voltage also
was designed as multiples of 11.
Hence the insulators has to be designed for these volatges and
hence the form factor coincidently derived as 1.11.

Answer / chandru_williams

I srrongly disagree with Kavitha. Insulators are made only
for the volateg ratings produced ( 11KV). The actual reason
is as follows.





1. When an alternator generates voltage, its rms value is
given by 4.4*f*$*t, where $ is value of total flux per
pole. So we can see all the voltages are made inevitably
multiple of this value (1.1, which is the form factor of
ac wave). Also it provides us the best economic
construction of step up and step down transformers.







2. We always use a multiple of 1.11 bcoz for a pure sine
wave the FORM FACTOR is the ratio of rms value of voltage
or

current with the avg. value of voltage or current and for
pure sine wave rms value of current is Imax/root '2' and

avg. value is 2Imax/pie. and which comes out to be 1.11 so
we cant have a combination of other then a multiple of 1.11.

Answer / a.mohanasundaram

i) Generating voltage strength (11KV) depends on dielectric strength of insulating materials to withstand heat loss produced by the main HV winding (armature). India has developed insulating material to generate maximum of 11KV (rms)
i.e) magV directly proptional to insulating material thickness

ii) Transmission votage is multiples of 11 bcaz
form factor = Vrms / Vavg=1.11 (sine wave)
to make average voltage 10 KV , rms sent as 11KV or 10% drop in voltage considered

Answer / shekhar

out of all these answers divyaprabha's ans is correct it is
the form factor only which is responsible for such rating
form factor for sinusoidal wave is 1.11.

Answer / bhushan

it is only because of form factor which plays role in
generation of electricity but i want more justification

Answer / soumya ranjan panigrahi

we know form factor is the cause of generating voltage in India is 11kV or it be transmitted as multiples of 11, because of simple to desine.
but now there is 13.2 kv generating voltage in ttps and 15.75 kv at ibthermal
it is not 220 kv because of insulation cost is high or insulation is bigger .
we know generators aRE dynamic machines produces high amount of heat and also we know the insulations are negative coefficient of heat so higher voltage generate means more heat generate then insulation are lose his property so we need more insulation

if my statement is wrong plz contact me soumya1988@gmail.com
b'coz i want to know more about this

please send me the L&T Emb. sys. placement papers and entire details of pattren

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