Question { NTPC, 4847 }

suppose there is afault in transmission line connected to a
generating station, then what r the adjustments u will take
to without loss of synchronism?????

Answer

Mainly mho relay helps to aviod synchronism problem for alternators .also damper windings,other protection relays like under voltage relay, over current, voltage relay also provides protection scheme

Question { Power Grid, 54279 }

what are the various types of towers used in transmission
line

Answer

Type A Tower (Tangent Tower with suspension string)-Used on straight runs and up to 2° line diversion
 Type B Tower (Small Angle Tower with tension string)-Used for line deviation from 2° to 15°
 Type C Tower (Medium Angle Tower with tension string- Used for line deviation from 15° to 30°.
 Type D Tower (Large angle tower with tension string)- Used for line deviation from 30° to 60°
 Type E Tower (Dead End Tower with tension string- Used for line termination & starting
 Special tower-
 Suspension Tower (Span ≈ 1000 m)
o Used for River crossing, Mountain crossing etc.
 Transposition Tower
o Used for transposition of tower

Question { IOCL, 10642 }

wat do knw aboot circuit breakers ?

Answer

CIRCUIT BREAKER IS OVER CURRENT PROTECTIVE DEVICE WHICH CAN BE OPERATED MANUALLY OR AUTOMATICALLY UNDER ABNORMAL CONDITIONS.IT IS REUSABLE PROTECTIVE DEVICE UNLIKE FUSE.

Question { IOCL, 25149 }

why dc series moter is not started at no load?

Answer

in dc motor speed is directly proportional to (v-i*r)/(flux). in dc series motor flux is depend on load current. if no load current speed is infinite and it is dangerous and un satisfactory.

Question { IOCL, 17571 }

is dc shunt moter oprate on ac? if no why? if yes how?

Answer

yes, as dc shunt motor commutator converts dc to ac supply to windings, but there will be sparking at brushes as ac changes it's polarity frequently so it is not satisfactory operation, and motor gets heated easily this may leads to failure of insulation.

Question { IOCL, 17571 }

is dc shunt moter oprate on ac? if no why? if yes how?

Answer

yes, in dc motor commutator produces opposite poles and alternating magnetic field using dc. but on using ac this magnetic reversals is very high and frequent causes sparking at brushes. so it is not satisfactory and danger.

Question { Power Grid, 33693 }

what is the ground clearance of 400KV transmission line?

Answer

8.8m As per IE Rules 1956,for EHT line the clearance above ground
of the lowest conductor shall not be less than 5.2 m + 0.3 m
for every 33000 V