Ans: The material properties of ferromagnetic substances
having great importance in selecting frequency. Frequency
range from 45 Hz to 70 Hz is useable region.
Another consideration is the core and copper loss. In core
loss, the power loss is proportional to frequency, and for
copper loss, is proportional to sq.of frequency.
Developing countries like India, defenitely select the
chepest option, thats 50 HZ.
Another consideration is equipment availablity.
Equipment availibility is only in the range of 50 Hz and 60
Hz. If we chose some other frq. say 70 Hz, Indian
manufactures has to produce accordingly, and that will
create less utilization of ferro magnetic materials.
From above, the conclusion is 50Hz is most suitable and
Yes we can use another frequency but for this change we have
to change in our power system such as
(1) As we know in generating stations the alternator is used
for producing electric energy and its frequency is given by
where Ns is synchronous speed and P is number of poles so
for increasing the frequency we have to increase the number
of poles which becomes very costly & so uneconomically
And another reason is that we used electrical instrument
which are standardized at 50 hz, 230 v
so we have to also change our electrical systems which are
also very costly
so this is only standard value we can change it but it is
being a colony of britishers for about 200yrs, all the
standards in india were set up by the britishers.this is
because the frequency in india is tuned to 50hz, since the
british follow the same.after the post independence period
if our country would have changed some other frequency it
would be a huge hurdel in development of a country like
india, since all the machines and the entire power system
was tuned to 50hz and replacing it would cost huge for
india.presently if it is done then the effiency of all the
machines and the entire power system would be drop by 20%
resulting a drop in india's growth rate.
as far as the range of frequency is concerened it lies in
the band of 45 to 70 hz (which is most efficient) and we
took the average or closest to the average i.e 50 or 60hz.
For a Electrical system to get synchronised, one of the
condition to get satisfy is the system frequency.
If frequency to be changed , then it is to be considered
right from power generation system.
While changing the frequency of the stationthe following
factors to be considered.
Frequency = 12o*poles/speed of the machine.
If this frequency factor to get change.....then pole of the
machine and the speed of the machine has to design
accordingly, which is quite inefficient and many factors to
be further considered.
there are many reason behind the use of 5o hz ...
1. in india all power plant set on the basis of given formula.
F = (P * N) / 120
where F = Frequency (in Hz)
P = the number of poles of the generator rotor
N = Speed of generator rotor (in RPM)
F*120=p*N should be equal to 6000.
if the we change the frequency the we have to change the 6000 factor which is uneconomical
2. core is combination of hysteresis loss and eddy current loss
hysteresis loss is directly proportional to the frequency and the eddy loss is directly proportional to square of the frequency. therefore as we increase the frequencies these loss also increase...
3. skin effect is depend on the frequency as we increase the frequency the skin effect is increases in the transmission line and the line become more resistive and copper loss is increase..
4. the using of ferromagnetic substance works efficiently on the frequency in between 44 hz to 70hz and the we go beyond the 70hz the life of the substance is decreases....
being a colony of the britishers for about 200yrs ,all the
standards in india were set up by the britishers.therefore
the frequency in india is tuned to 50hz since the same is
used by the britishers.after the post independence period
if india would have changed its frequency then it would
cost a lot to india and will be a huge hurdel in the
development of a country like india.as far the range is
concerened it lies in the band of 45 to 75hz(which is most
efficient) and we use the average or the figure i.e 50 or
60hz.at present if we change the frequency then the
efficiency of all the machines and the entire power system
will be drop by about 20% which in return would drop the
growth rate of india .
It is the standard frequency for India whereas for other
countries it is(110v,60hz).The appliances in India work
only for 50hz frequency.v can change d frequency as in
CYCLOCONVERTERS as the voltage changes frequency also
changes but the output frequency(variable) is lower than
input frequency(fixed).The appliances brought from USA/sum
oder country with(60hz) cant be used in India.Our
requirment is 2 increase the frequency rather dan
In India power generating stations are designed with
alternator which runs on 4 pole.
Since we have formula for syncronous speed
Ns=120f/P ; where f - frequency
p - No of Poles
It is possible to change frequency more than 50 hz, but it
will be a costly affair. We need to design our generating
system for more than 4 poles. second reason is that our
electrical equipments are pre-designed to operate on 50 hz.
If we change 50 hz to some other frequency it is same as
rebuilding INDIA again.
Actually Britishers have decided it. Since our human eye has
minimum rage of 12hz. so,on our electrical basis 12*4=48Hz
nearly 50hz has been fixed.Once if we change this all our
power systems should be changed.there should be fixed grid
frequency to use it entire the country.
Sir we have 12.5 MVA(110/11KV) transformer (Y-Y)
connected,which tripped showing earth fault,when we charged
transformer it stood OK ,but on connecting 11 KV feeders it
tripped showing earth fault.our service engineers found that
the B phase and R phase phase connecting to neutral broken
from HV OLTC(on load tap changer),and R phase and Neutral is
ok.Dissolved gas analysis shows that accetline content is
high,tan delta value is 12.My dout is it is an internal
fault of transformer,why REF or diffrential relay is not