Answer / rakesh maurya

In India the electrical supply is based on 230 V Ac supply.
Countries that now use the 50 Hz frequency tend to use 230
V, and those that now use 60 Hz tend to use 120 V.

Unless specified by the manufacturer to operate on either 50
or 60 Hz, appliances may not operate efficiently or even
safely if used on other than the intended supply frequency
Reasons :
Several factors influence the choice of frequency in an AC
system. Lighting, motors, transformers, generators and
transmission lines all have characteristics which depend on
the power frequency.

The first applications of commercial electric power were
incandescent lighting and commutator-type electric motors.
Both devices operate well on DC, but DC cannot be easily
transmitted long distances at utilization voltage and also
cannot be easily changed in voltage.

With AC, transformers can be used to step down high
transmission voltages to lower utilization voltage. Since,
for a given power level, the dimensions of a transformer are
roughly inversely proportional to frequency, a system with
many transformers would be more economical at a higher
frequency.

If an incandescent lamp is operated off a low-frequency
current, the filament cools on each half-cycle of the
alternating current, leading to perceptible change in
brightness and flicker of the lamps; the effect is more
pronounced with arc lamps, and the later mercury-vapor and
fluorescent lamps.

Commutator-type motors do not operate well on high-frequency
AC since the rapid changes of current are opposed by the
inductance of the motor field; even today, although
commutator-type universal motors are common in household
appliances, they are universally of low ratings less than 1
kW. Once the induction motor had been developed, it was
found to work well on frequencies around 50 to 60 Hz but
with the materials available in the late 1800s would not
work well at a frequency of, say, 133 Hz. There is a fixed
relationship between the number of magnetic poles in the
induction motor field, the frequency of the alternating
current, and the rotation speed; so, a given standard speed
limits the choice of frequency (and the reverse).

Electric power transmission over long lines favors lower
frequencies. The effects of the distributed capacitance and
inductance of the line are less at low frequency.

Generators operated by slow-speed engines will produce lower
frequencies, for a given number of poles, than those
operated by, for example, a high-speed steam turbine. For
very slow prime mover speeds, it would be costly to build a
generator with enough poles to provide a high AC frequency.
As well, synchronizing two generators to the same speed was
found to be easier at lower speeds.

Generators can only be interconnected to operate in parallel
if they are of the same frequency and wave-shape. By
standardizing the frequency used, generators in a geographic
area can be interconnected, providing reliability and cost
savings.

Direct-current power was not entirely displaced by
alternating current and was useful in railway and
electrochemical processes. Prior to the development of
mercury arc valve rectifiers, rotary converters were used to
produce DC power from AC. Like other commutator-type
machines, these worked better with lower frequencies.

All of these factors interact and make selection of a power
frequency a matter of considerable importance. The best
frequency is a compromise between contradictory requirements.

Answer / maheswaran

if we go for higher frequencies,skin effect is more.. and
we have to change the design the equipments..

Answer / vijaya kumar

if we choose other freequency suppose 60hz ,our standara
freequency is 50hz.for transfer of power there must be same
freequency.Also if freequency increases number of poles
also increases,if poles inc.d diameter of equipment also
inc.it leads to high cost.

Answer / karthikeyan

The reason why in our country we are generating and
distributing the power with 50Hz/sec is, when frequency
increases say 60Hz/sec the losses in transmission and
distribution, transformers and active loads will be high.
economically 60Hz/Sec not affordable in our country.
because copper very high in cost.

Answer / nimish

It is a traditional system which has been established. all
the euipments are designed on the basis of 50 Hz so if we
change the freqency all the equipmets get damaged so we can
not change the frequency.

Answer / eduard

it depends to equipment rated hz some equipment has
indicate 50/60HZ as you can see to the name plate... when
your equipment is 50HZ and its indicate as above it can be
use...

Answer / ajay sant

all above answers are correct in its place but we forget
basic thing when we design any system following parameters
are to be taken into considaration
1.avrage temp.
2.avrage sea lavel
3.windvelocity
4.distance
5.size
considering all these factors 50HZ frequency is most
economical system thats why we use 50Hz

Answer / m.sureshkumar

in orfer to increase freq. wehave to increase the turbine
speed in power generating station. for that we need some
what more fuel(for diesel turbine) or water (for water
turbine). so it may lead coat effective.

Answer / ismail

IN INDIA THERE IS A STANDARD FREQUENCY IT IS 50HZ BUT IN
OUTHER COUNTRYS IT IS 60HZ IT IS STANDARD

Answer / rathor sumit k

yes we can choose but the some what high frequncy will
required low volt becuase pressure for electron flow
already affected by high freq. and vice versa

what is mean by restructuring power system?

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