Question { ABB, 18151 }

if we convert watt into kva,which one formula use by us,pls
tell me?

Answer

w = 1000(V*I)/cos phi =KVA

Question { 3761 }

if dc is better then ac...then why we are perfering ac over
dc?eg:at home?

Answer

AC can easily be stepped up or stepped down. specially for
transmission we must have high voltages in order to have
low losses,
while stepping up or stepping down dc is very complex and
expensive.
this is the main feature that we consider,
while of course dc is better as dc resistance is lower than
ac resistance,no reactance and power factor problems,

Question { TVS, 9080 }

What is indipendant power plant

Answer

that power plant which is owned by a private firm not by
governments authorities. the private owner sells power to
the govt.

Question { Dalkia, 4664 }

1.Why we use choke?If we use for high starting voltage then
different type choke gives different voltage. Is it correct?

Answer

choke is an inductor used in tube lights to limit the
voltage, it is not used as stater..

Question { Bhel, 8073 }

what happen when dc supply is given to the transformer

Answer

the transformer will burn as the resistance of the winding
is very low. and will act as a short circuit

Question { Bhel, 8073 }

what happen when dc supply is given to the transformer

Answer

If DC voltage is applied to the primary of a transformer the
flux produced in the transformer core, will not vary but
remain constant in magnitude therefore no emf will be
induced in the secondary winding except at the time of
switching on.Also there will be no self induced emf in the
primary winding to oppose the applied voltage and since the
resistance of the primary winding is quite low heavy current
will flow through it which may result in burning out of
primary winding