Board- Shri Arvind Saxena
Electrical AIR 6
Interview score- 142/200
DATE- November 2, 2016
Time- 9:00 AM
I reached UPSC bhavan around 8 AM. First there were many security checks and briefings. then, they will make you wait in the waiting room. a peon will call as your turn comes. Boards were allotted to the groups on interview day itself. We were told that we had a board of Arvind saxena. There were 4 members (IAS Arvind Saxena and 3 Technical Advisors) in the interview panel, i didn’t knew other three but i believe they were professors from IIT Delhi and Bombay as i have seen them in NPTEL videos. Anyway i will call them AS (Arvind saxena), P1, P2 and P3.
I entered the room there was large table with AS sitting in the middle.
I greeted them all and wished them before asking permission to sit.
AS(Going through my DAF) : So, Mufeed You are from Integrated Dual Degree. Do you get separate degrees of B.Tech and M.Tech or combined?
Me: Sir, We get separate degrees. Earlier we use to get combined degrees.
AS: How is it different from separate B.Tech and M.Tech?
Me: Sir, in these programmes we get direct admission through JEE and not through gate. Also, a student of IDD(Integrated Dual Degree) saves one year as compared to student going to pursue M.tech through Gate. We cover similar courses with B.Tech students till third year ,after that we also attend specialised M.Tech courses.
AS: You have a good CG . Were You the topper?
Me: Nodded with a yes
AS: OK Mufeed tell me why a person gets burn injury if electrocuted?
Me: Sir, it depends on the magnitude of voltage ,if the voltage is high to produce an arc then burn injury happens due to the heat of the arc but not at low voltage.
AS: What are the changes that occur inside human body when a current is passed through it?
Me: Sir, I am unaware of exact biological phenomena but i have read that current causes muscle contraction and if heart muscles are in the path of current then fibrillation can cause heart muscles to stop. It also depends on the magnitude of current and duration for which current is flowing.
AS: For domestic purposes why MCB’s are used?
Me: Sir, MCB’s are automatically operated electrical switches that are designed to protect humans and equipments from shocks and to isolate faulty parts of the circuit.
AS: Can you explain its working?
Me: Sir, these are low voltage CB’s which uses air as extinguishing medium. Mostly, They works on the heating effect of current. When current exceeds normal limit then bimetallic strip send a trip signal which releases the loaded spring interrupting the supply.
AS: Are there any other CB’s which works on some other phenomena and not heating effect?
Me: Yes sir, There are many breakers which works on magnetic effect of current also.
AS: working on heating principle takes time. Suppose if someone gets shock then there can be delay in operation. what do you think?
Me(I was unaware of the answer but tried anyway): Yes sir that’s true, but i think main reason of not using fast breakers for domestic purpose is the cost . Also , the magnitude of voltage is low in households that’s why i think thermal effect based breakers are preferred.
AS: Are you still working ?
Me : sir, I was working with Eaton technologies , i resigned last month.
AS: what you will do now?
Me(smiling): Sir, i will join Engineering services.
AS then asked P1 to take over from here and continue.
P1: What is the installed power generation capacity in India?
Me: Sir, around 305 GW.
P1: What is the power consumption in India?
Me: Sir, Around 190 GW.
P1: Why there is mismatch in supply and demand?
Me: Its due to the transmission losses and also , all power plants do not run at full capacity.
P1: What fascinates you more, solar or nuclear power?
Me: Sir, solar energy as it has the potential of reaching every person and every place. distributed generation is possible in solar energy. Anyone can harness it given the right infra.
P1: Explain the working of solar panel?
Me: Answered with details about low efficiency and cost effects.
P1: Are these panels used in india being manufactured here or imported?
Me: Part of these are manufactured in india itself but due to high cost and low efficiency they are normally imported.
P1 :What is the per unit electricity cost in your city?
Me: Approx. Rs. 6 per unit.
P1: should we spend more on generating non renewable sources like solar energy what do you think? considering the high cost of solar panels ?
Me: As the energy demand in India is continuously increasing , depending only on the limited conventional sources is not feasible option. We should spend more on research areas to bring down the current high cost associated with renewable energy sources to meet our future energy needs .
P1 referred to P2 to ask further questions
P2: Suppose we need to transfer bulk power at HV, will a single conductor is preferred or more than one and why?
Me: For transferring power at HV generally Bundled conductors are preferred , apart from many advantages they help in reducing corona.
P2: What is corona?
P2: What is its disadvantages?
P2: Is there any advantage of corona?
Me: Yes, on a small scale it acts as natural protection against lightening discharging extra energy.
P2: Can you explain power transfer through a transmission line by using EMT?
ME: explained in a sheet of paper using wave equation.(refer stevenson)
P2 : In a substation we are switching on a transformer and the relay is going off , what possible reason can be there?
Me: It can occur due to large inrush current, which can be avoided by switching on the transformer at the right voltage cycle.
P2: Explain in detail?
Me: answered inrush current phenomena with voltage and flux cycle.
P2 reffered to P3 to ask further
P3: What are losses in a transformercore?
Me: answered (Iron and copper losses)
P3: how to avoid them?
P3: what types of materials are being used nowadays to manufacture cores?
Me: Sir, normally si steels are being used. for HF ferrite cores are used.
P3: any other?
Me: air core, mangnese etc. Sorry sir, i am not able to recall more.
Then AS asked me
As: Will you join Engineering Services if selected?
Me:(instantly with a smile) Absolutely sir.
As: Ok mufeed Thankyou
I stand up and thanked them all while going out.