Answer / mohammed.muqtar

not less than one cable diameter between cables as per NEC 392.11(A)(3) for multi conductor cables in open single layer cables trays.

Any one can explain if there is any harm from humming noise heard from air circuit breaker : we have 415 switch board having two incomers from transformers 3.3KV/415V , when bus coupler closed, and open one ACB incomer to work in one of the transformers, the current started hunting around 50 Amps, and heard humming noise from the air circuit breaker, although the load current was only 1200 amps while the ACB capacity is 2500 Amps, and the transformer 1600 KVA. The same didn't happen when taken the other transformer offline. Why this humming noise and current fluctuation? is there any implication or danger, bearing in mind that we just returned everything back to normal and stopped the maintenance of the transformer. Shall we go ahead and ignore this noise?

6 Answers  

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WHY WE NEED NEUTRAL FOR 3PH 400 OR 415 VOLTS POWER SUPPLY (4 WIRE SOURCE).

5 Answers  

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Is it possible to power factor more than unity?

9 Answers   BEL,

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How can we get a Neutral from a three phase suply? If we meet all three phases at a point to take neutral then why dont thay get sparked?

1 Answers  

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A cotter joint is generally used to transmit

0 Answers   Caterpillar,

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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?????

2 Answers   NTPC,

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What is quadrantal symmetry?

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if any body have question paper of railway (section engineering),then plz send me .i will thank of him/her.

0 Answers  

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what is the difference between multimeter and megger?

3 Answers   Bhel, Metro,

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Why a transformer Noise during its running condition ?

8 Answers   NTPC,

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Based on CPI/CGPA they shortlist the candidates & than directly start Interview so there is no Written Exam or GD Only PI.Interview held @ MNNIT , ALLAHABAD On-Campus on 6th,Aug, 2007 & the Questions asked to me by Interview Board ( 4 People) are from HR/SummerTraining/BTP/Subject-core, POWER SYSTEM & MACHINE. time duration of I/V is about 15-20 Minutes. HR- Q.1 Name,hobbies & About family background ? Q2.What u know abt NTPC ?? Q3.Why u want to choose NTPC as ur Carrier's starting i.e power sector not any other Oragnisation or sector ?? Techincal Questions- Q1.What is the reason for transformer Noise ?? Q2.Which material is used for making Transformer oil & How u measure its dielectric strength & Name the test ? Q.3 Which Machine u will prefer 2 use if flammble gases are coming out at a place & why ?? Q4.What is relation b/w Transmission Lines & Communication Lines ? Q5.What is the maximum capacity Synchronus Machine & total powerGeneration in our country ? Q.6 In india Power generation is at 50Hz while in America its 60 hz ,why so ?? Advantage or disadvantage ?? Q.7 Maximum Generation Voltage in india ? Q8. What is the Voltage regulation & why its required n how much is permissible ? & causes of voltage variation ?? Q.9 Why electric shock is feel ?? n in a Electric Train why we didnt feel that ? Q.10 Have u seen/ experience of any power plant/ industry related to the power sector ? so these are the questions which not too diffcult i think was asked to me.

6 Answers   NTPC,

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without name plate detail of blower how we can find out the HP & Rpm ? the input voltage is 230v single phase

1 Answers  

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