k.prakashchandra


{ City } karkala
< Country > india
* Profession * rtd e.e.
User No # 54717
Total Questions Posted # 0
Total Answers Posted # 521

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Answers / { k.prakashchandra }

Question { 4684 }

How to generate neutral in DG set?


Answer

If it is single phase earth one of the terminals to treat it as neutral ( actually there is no neutral for single phase source). If 3 phase, earth the star point

Is This Answer Correct ?    4 Yes 0 No

Question { EESINT, 2444 }

how we control the magnitude of a generator output


Answer

By controlling input to prime mover

Is This Answer Correct ?    2 Yes 2 No


Question { 10886 }

meter ratio is 100/5 CT ratio is 125/5, when the ratios changes i.e., CT ratio is 125/5 meter ratio is 100/5 what is the MF in boths conditions?


Answer

Meter 100/5 A ,and Ct 125/5 . For 100A load current the CT secondary current is 4A which is taken as '80A load current 'by the meter . Hence M.F. is 125/100 or 1.25

Is This Answer Correct ?    0 Yes 0 No

Question { KPTCL, 2826 }

We have 11kV/110V three phase indoor potential transformer in 66/11kV Sub-station, where the failure of PT is frequently happening and the rating of the PT is 0.2 class accuracy, with primary star and seconday (two cores) star connected.
Some experts has suggested to not to connect the PT Primary neutral to the ground because when transformer neutal NCT connection is loose; the faulty current will flow through the PT primary neutral, resulting into failure of PT.
My question is: Is it necessary to remove the primary neutral connection of the PT from ground? if not, what would be the reason for failure of PT.
Please guide me.


Answer

Intimate whether PT fails whenever there is an earth fault and which winding fails

Is This Answer Correct ?    0 Yes 0 No

Question { WAPDA Water and Power Development Authority, 5373 }

how to calculate the slowness and fastness of energy meter if we have different kw load for example (0.746 kw and meter rev constant 400 and we calculate the 2 rev in 30 sec) please explain the formula thanks


Answer

Meter rev constant means rev/ kwh ? Then one rotation =60x60/400 or 9kws . 2 rotations = 18kws.Time taken is 30s. Then the av load is 18/ 30 or 0.6 kw

Is This Answer Correct ?    2 Yes 2 No

Question { GOMS, 2391 }

why we not use capcitor in Three phase motor ??


Answer

You can use for reducing the line current by improving pf

Is This Answer Correct ?    1 Yes 0 No

Question { Dewan Cement, 9100 }

What is the difference between PT for metering and PT for protection ?


Answer

Metering PT s are more accurate ( 1, 0.5 ,0.2 )for 80% t0 120% of rated voltage .

Is This Answer Correct ?    3 Yes 0 No

Question { Cenored, 6892 }

What does dny11 stand for?


Answer

It should be Dyn11

Is This Answer Correct ?    1 Yes 0 No

Question { Laurus, 3892 }

How to calculate the 2500 Kva Transformer losses Primary 11KV Secondary 415volts


Answer

Iron losses may be taken as 2 KW i.e. 2 units per hour . For max efficiency Copper losses are equal to iron losses

Is This Answer Correct ?    0 Yes 0 No

Question { 2273 }

Neutral CT for 45MVA 132/11 KV YNd11 Transformer. NCT REF CLASS-PS or 5P20 with 20VA burden which is suitable.


Answer

NCT should be identical to line CTS

Is This Answer Correct ?    0 Yes 0 No

Question { TATA, 4585 }

11 KV distribution system where neutral is produced ?


Answer

For 11V supply , ground is the neutral as the neutral of the power tr at the MUSS is connected to earth

Is This Answer Correct ?    1 Yes 1 No

Question { Deltin Jaqk, 2495 }

How a ship getting grounded


Answer

Its huge metal body acts as ground

Is This Answer Correct ?    1 Yes 1 No

Question { State Board, 1744 }

auto reclosing scheme for radial ehv feeder is to be implemented or not?


Answer

It is recommended in view of system stability

Is This Answer Correct ?    1 Yes 0 No

Question { Thermax, 2429 }

After synchronizing the running generator with grid, the avr getting tripped and the generator breaker also oettong tripped, before tripping the avr the pf meter of generator is showing leading pf please kindly give a suggestion to rectify this problem.


Answer

If AVR trips UCB has to trip either for LOE(loss of excitation ) or reverse power .Leading pf indicates gen voltage lower than grid voltage . Check the measuring PTs. Is is better to synchronize manually before resorting to Auto. Check the synchroscope also

Is This Answer Correct ?    2 Yes 0 No

Question { Thermax, 2429 }

After synchronizing the running generator with grid, the avr getting tripped and the generator breaker also oettong tripped, before tripping the avr the pf meter of generator is showing leading pf please kindly give a suggestion to rectify this problem.


Answer

As told by somebody , the phase sequence in the AVR should be as that of gen

Is This Answer Correct ?    0 Yes 0 No

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