Question { 15410 }

why stator winding of synchronous machine are connected in
star connection ?

Answer

The stator windings are connected in star because for the
same line voltage generated in an alternator or fed in case
of a motor the per phase voltage induced will only be
v/1.732 , hence the no. of turns required will be less and
hence the copper material required will also be less ,
besides te star connection also enables the provision of a
neutral which can aid in safe passage of fault currents .

Question { 11240 }

What is the difference between induction generator and
synchronous generator?

Answer

an induction generator is one which needs a continuous
supply from the mains , that is it is not self starting it
needs to be first started as an induction motor and then
the primemover torque be applied in opposite to the
electromagnetic toreque so that the rotor startss moving at
a sped greater than the synchronous speed , while a
synchronous generatore is self starting and requires only
prime mover torque which rotates it in the direction
opposite to electromagneticc torque and it rotates with the
synchronous speed

Question { 12751 }

Current chopping mainly occurs in air blast circuit breaker.why?

Answer

In an air blast breaker a high velocity jet of air is made
to flow through the arcing contacts that extinguishes the
arc much before natural ac current 0 is reached , the air
blast breaker retains the same extinguishing power
irrespective of the nature of the fault , onsequently the
blast of air sweeps out the ionised particles in between
the contacts thereby buiding the rsistance and hence
ultimately extnguishing the arc .