Transformer's core is made up of which material and why so?

Draw the line diagram of diffretial relay connected to transformer?

Name different types of fault and which instrument is used to measures earth,short,open cicuit fault?

AC current is flowing in a wire in your home how can you measure it(name of the instrument)

why knee point voltage should be high in Ct for differential protection

what is the function of a commutator in a dc generator?

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.

Questions :- HR- Q.1 about yourself & family background ? Q.2 Why u choose Power sector as ur carrier starting not any other sector ?? Q. 3 What think abt NTPC ? Techincal Questions:- Q.1 about Vocational Training……What u did , see the main equipments….etc Q.2 Why a transformer Noise during its running condition ? Q.3 about transformer oil material & Test name for the measurement of its dielectric strength & wht will u do if its dielectric strength goes low ? ……..some discussion type ? Q.4 What is relation between transmission lines & Communication lines ? Q.5 Which Machine u will prefer to use at a place where flammable gases are coming out & why ? Q.6 how fault in an electric system is detected & hw protection of equipments is done ? Q.7 Why we didn’t feel electric shock in an electric train ?? Q.8 Anything u want to ask from us ??

Why a Transformer Noise during its running condition ??

How the Transformer oil testing is done & Why oil dielectric goes LOW & what is solution for that ??

What is the Maximum Power generation capacity of a Synchronus Machine ??

What is the Total Power generation Capacity in India at present ??

What is the function of Lightning Arrester & Wavetrap in Power system ??

Why Power generation in India is at 50Hz while in America its 60Hz so is there any advantage/Disadvantage of this ??

which Machine u will prefer to use at place where Flammable gases are coming out & why ??