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.

2 Answers   KPTCL,

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Explain how you intend to work under pressure to meet up with deadline target?

0 Answers  

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what type of insulation is used for over head lines?

4 Answers   NTPC, WS,

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what is control supply rating of a machine

0 Answers  

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RESISTONS R1 AND R2 in parallel = Total R.? 1-R=R1+R2 2-R=1/R1 + 1/R2 3-1/R + R1+R2 R=R1R2/R1+R2 select one

2 Answers   BSNL, PGVCL Paschim Gujarat Vij Company Limited, TCS, Wartsila,

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why power factor is important?

6 Answers   Dalkia, MGC,

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I hv a question regarding power factor improvement just after transformer. I request you to reply me plzz. thank you sir. My friend has a small unit of fabrication. in his factory the main load is a welding machine, lathe machine, grinding machine. this load is not continuous type. now our electricity board has installed 16 KVA, 11000/433 V transformer for our factory. In the energy meter (trivector meter) at LV side of transformer, i hv seen power factor value of 0.15 only when only 3 KW load was flowing. Further electricity board has suggested to install 4 KVAR capacitor at LV side after energy meter. Now my question is that if we permanantly install and switch on 4 KVAR capacitor after energy meter, during some load on transformer and also without any load on transformer, wht will be the power factor shown in energy meter?i dont want to get any penalty by electricity board, so plz suggest me if i can permanantly install and switch on the 4 kvar capacitor or not at LV side of transformer just after energy meter? Thank you again and awaiting for ur positive reply soon.

9 Answers  

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I have 90KW Motor 60 Hz,380V Pf 0,88. after testing the Motor without Load is the no load Current 36 A,but wenn i put load after 2 hours the current increase more than 156 A. Can anybode tell me waht is the Problem?

4 Answers   ABB,

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Sir,In our company there are 3 caterpillar make(capacity:(1) 3.3KV,2.5MW(2)3.3KV,2.5MW & (3)3.3KV,1.9MW) & 1 deutz make (capacity:11KV,3.8MW)gas engines utilised,all are running in paralell. There are three transformer utilised,(1) 6.25MVA,3.3KV/22KV,Impedence voltage:6.7% used for two generator,both are 2.5MW(2)5.5MVA,3.3KV/22KV,Impedence voltage:7.2% used for one generator of 2.5MW & (3) 5.5MVA,11KV/22KV,Impedence voltage:7.8% used for one generator of 2.5MW.all generator breakers capacity of 1250Amps. Sir,I want the details of fault level calculation of generator,transformer individually & for whole system. If you require any information from me.feel free for contact me sir.pl.send the answer of my question as the earliest as possible.

0 Answers   Piramal Healthcare,

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Explain difference between stand by earth fault and residual earth fault protection?

0 Answers  

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How to desaturate a saturated CT of PS Class?

4 Answers   Electrical,

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why CT ratio stand for 50/5, 100/5, 25/5.

11 Answers   ABB, Ramky,

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