Interested to Buy Any Domain ? << Click Here >> for more details...
why is power supplied in 3 phase only? why not in 2 or 4
phases?
- 11 Answers
- 33713 Views
- I also Faced
- E-Mail Answers
Answer Posted / amol wazalwar
multiphase systems are very much possible but the problem is
the higher cost. we need a minimum of two phases for
production of a rotating magnetic field , this is one of the
reasons why the earliest generation was done in two phases.
But three phase provides us with the optimum compromise
between the power transfer capability and the the cost of
generation and transmission of electricity. i will give you
a brief mathematical derivation of why we use three phase
and not more than three phases.
let us assume a single phase system with the induced and
current I .
power output = E*I
assuming unity pf
for a two phase system , let us suppose that the induced
voltage is still E and current I
per phase voltage in a two phase system = 1/root(2) * E
(with two conductors in series and 90 deg electrically apart.
so power output = 2*1/root(2) * E *I
= root(2) *E*I
= 1.414 EI
for a three phase system , let the induced voltage still be
E and the current I
per phase voltage in a three phase system = 1/2 * E (with
three conductors in series and 120 deg electrically apart.
so power output = 3/2 * E *I = 1.5 EI
thus for a n phase system let the induced voltage still be E
and the current I
per phase voltage in a n phase system = piE/2n
so power output = n * piE/2n * I = 1.57 EI
thus from the above it can be seen that when we move from
single phase to two phase the power delivered increases by
42% then in three phase by 50% and in a n phase or higher
phases maximum by 57 %
thus 3 phase provides the optimum compromise between the
power delivered and the economics of laying n no of wires.
note * - well the last derivation i had given assumes a very
large no of phases. the problem can be visualized as trying
to fit n no of phases in a semicircle with dia as E. so for
a large no of phases emf per conductor can be taken as
length of the semicircle / no of phases
(pi *E/2)/ n
pi E/ 2n
| Is This Answer Correct ? | 22 Yes | 9 No |
Post New Answer View All Answers
what is allowed value of zero sequence impedancce of 6.6 kv nuetral earthing transformer ?what is the actual value
what are the applications of PLC?
WHY CBCT USE ONLY IN Y PHASE NOT OTHER PHASES
what is meant by vector group of a transformer? How can it be derived?
List the power rating of any 5 important electrical appliances used in houses.
iam using DM 3251 voltmeter(1 percent accuracy)for 11KV system PT ratio is 11KV/110V.can anybody explain what is the max and min voltage deviation.
Which device is used for the source of emission of electrons in a crt?
What are chief characteristics of state-space method and its techniques ?
what is transistors comprised of?
HELLO SIR, IAM PREPARING HPCL EXAMS. SO PLS SEND MATERIAL OF HPCL ELECTRICAL ENG..TO VIJAY_8888@YMAIL.COM
what is meant by skew width in machines?
Why we make earth connection with Transformer Body and What will be the minimum size of copper wire as per code with respect to KVA rating of Transformer?
What do you understand by external characteristics of a d.c. Generator?
Why it need to form a capcitor when it not been in use from three or two year. Plz describe it technically.
What types of high speed CMOS circuits have you designed?
