Question { L&T, 48456 }

WHY THE FREQUENCY IS 50 HZ IN INDIA.CAN WE USE SOME OTHER
FREQUENCY.IF SO WHAT IS THE RANGE AND WHAT WILL BE THE
EFFECT IN PRESENT POWER SYSTEM IF WE CHANGE THE FREQUENCY
AS YOU SUGGEST ?

Answer

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.

Question { 31428 }

WHAT IS THE DIFFERENCE BETWEEN KW AND KVA ?

Answer

kva- apparent power
kw- active power
Var- reactive power

apparent power= active + reactive power

kva is printed on the transformer than kw because kw is just active power , whereas some reactive power(Var) is also involved there, therefor the total power i.e the apparent power(kva) is printed insted of active power(kw).