Question { GE, 54429 }

Why CT secondary is grounded?

Answer

ACTUALLY CT SECONDARY NEVER GROUNDED, CT WHEN CHARGED IT IS LOADED WITH BURDEN OF IT`S SECONDARY SHORT CIRCUITED.
CT IS OPPOSITE TO NORMAL TRANSFORMER. THE PRIMARY CURRENT IS DEPEND ON SECONDARY LOAD CURRENT IN NORMAL TRANSFORMER WHERE AS SECONDARY CURRENT IS DEPEND ON PRIMARY LINE CURRENT. IN CASE OF CT PRIMARY CURRENT IS VERY HIGH. THIS HIGH CURRENT PRODUCES FLUX IN CORE AND THIS HIGH FLUX INDUCES EMF IN SECONDARY WINDING. SINCE THE NUMBER OF TURNS IN SECONDARY ARE MORE, EMF INDUCES IS MORE AND IF SECONDARY IS OPEN THIS HIGH VOLTAGE MAY DAMAGE INSULATION AND CAUSE CT BURST. IF CT SECONDARY IS CONNECTED WITH LOAD OF SHORT CIRCUITED, THE LOAD CURRENT WILL FLOW AND THIS LOAD CURRENT WILL PRODUCES ITS OWN FLUX. THIS FLUX IS OPPOSITE TO MAIN FLUX AND RESULTANT FLUX WILL BE LOW AND HENCE THE EMF INDUCES WILL BE LOW. HENCE IN CT SECONDARY IS ALWAYS SHORT CIRCUITED OF CONNECTED WITH LOAD.

Question { 3960 }

What is breather? why we use it ?

Answer

Breather is use in transfoimer.
Due to continuous change in load conditions, oil in
transfomer comprased or expands. when oil comprased it take
external air in through breather. breather contains silica
gel which is used to absorb the moisture in air and supply
dry air in transformer conservator tank. If moisture
contained air passes in to the tank will mix with oil and
the BDV of oil will be low and hence the life of
transformer.

Question { TATA, 21151 }

1 unit or 1 kwh means how much kva

Answer

1 Kwh = Kva * 1 Hr * P.F.

Question { 14865 }

2 electric bulbs of 100w,200V are put in series & the
combination of each bulb is supplied to 100 V . the power
consumption of each bulb will be????????

Answer

100w each