Preperation for power engineering position interview 1

[Armen]

I am going to go for a power engineering position interview in the near future. Although my GPA is very high and I am a recent grad with an MSEE, I have taken only 2 power-related courses so far.

I will appreciate any suggestions as to how to prepare for this job interview in terms of technical subject matter preperation.

 

[SidiropoulosM]

For an entry-level position, which I suspect this one is, your qualifications are adequate. With the recent high tech internet "bubble", many universities have discontinued electric power engineering programs and qualified candidates are scarce. Some points of preparation:
(1)Find out as much info as possible about the firm, its business and the requirements of the position applied for, (2)Write down any questions you have about the firm and the job. You will ask these during the interview, in order to determine if the job matches your carreer plans,
(3) Anticipate their questions and write down your answers in advance, (4) Rehearse one day before the interview.

Good Luck, Michael Sidiropoulos

 

[jlazucena]

You should understand about
Per unit
Symmetrical components
Three phase short circuit calculation (Basic with utility impedance and neglecting utility impedance – also call infinite bus)
Over current protection
Overcurrent differential protection

It will help understanding about
Thevenin model of induction motors
Starting motors at reduced voltage
Line to ground short circuit calculation (Basic with utility impedance and neglecting utility impedance – also call infinite bus)
Basic modeling of synch machines (power angle equation)
Directional Overcurrent protection
Impedance relays

You should know that there would be transients when switching capacitor transmission lines, transformers

I am giving more than you need, I wanted to mention possible interview questions, do not forget the name of any software for PS-modeling that you have used at school

 

[peebee]

Most of your competition will likely be coming from BSE's or BSEE's with only one power class under the belt. Don't get too stressed.

 

[Modula2]

Why not work in a field corresponding to the education selected and obtained.

 

[neps3]

Hi Armen

Most graduates now a days are of the internet bubles. Engineers like to go into communications, control etc and there is a shortage of power system engineers. If an engineer is short of power apparatus knowledge (practical & theory) particularly practical aspect then they should go for what they have studied and qualified for.

Job statisfaction and contribution is quite important.

 

[joepower]

To answer you better, it helps to know the type of position that you are looking for - some such as electric utility system planning and stability studies require academic moxy, while most power engineering positions require an ability to order the right equipment and get it to work when it arrives.

One of the biggest complaints I’ve heard about entry level engineers is that they just want to spend time on the computer doing CAD, 3-D modeling, system studies, etc. None of them want to spend time writing an equipment specification, dealing with construction personnel, or making that string of 6 phone calls to find the right person or vendor to get the information or part that is needed.

In my opinion (and I am frequently outvoted), GPA is not that important. For example, I recently hired a new grad who had a good GPA and even some power courses, but to me his most important qualification was that he was captain of the school rugby team. This meant that he was used to running into things that don’t move, which is how a lot of your day will be spent. He has worked out great and in his first 6 months he has learned about 2 years worth of diverse engineering skills from detailed dc analysis calculations to project management.

Emphasize your people skills and writing skills. Most everything else will be secondary. People want to know that you will be able to deliver a project on time and on budget since that is becoming a rare thing these days. They do not want a great engineering design – they want a functional design in the time and budget constraints. Power engineering can be really fun because you will see large projects energized that you can see, feel and hear, not some microelectronic gate change that is more math than electrons. And because very few people are going into power, you have an unguaranteed shot at relative job security (if you don’t mind a move or two), and a not too shabby salary.

Let me know in more detail what the position is and I can give you more specific buzzwords and BS details for the interviewers.

Just for yucks, here is the actual “Knowledge Survey” (a.k.a. test) that I give senior electrical engineers when they interview. Almost every one is a trick question but will show a lot about what a guy knows:



1. Which section of the National Electrical Code deals with grounding? (article 250)

2. From NEC table 310-16, what is the maximum allowable design ampacity for a 90 C, 500 kcmil cable? Why, and are there exceptions? (I don’t have my book with me, but if you look up the value in the 90 C column you might be wrong. There is a note in the front f the code that limits an application to the temperature ratings of the devices. Most equipment below 100 A has terminations rated at 65 C, while larger ratings have terminations rated at 75 C. Therefore you can only use the 75 C as the maximum in most cases with the 90 C being used to account for various deratings)
3. Since the NEC does not address conduits run in direct sunlight, how should this be compensated for? (detailed IEEE table for these cases indicate that if you bump up the conductor size by one you are generally covered for the increased temperature and subsequent deratings – with and without wind makes a difference also, just like overhead transmission lines)

4. What are the four types of interrupting mediums for medium voltage switchgear. Circle the one that you would choose if no preference from a client were given? (oil, air, vacuum, and SF6 – today you are going to get vacuum in the US, although philosophically I have a preference for SF6 since even if the interrupter loses pressure, SF6 at atmospheric generally has enough dielectric strength to break under load to get it isolated, but not under fault.

5. When performing a coordination study involving a feeder to a large motor, what the values are need to define the motor curve? The circuit breaker characteristic should fit between this curve and what other curve? (full load amps, locked rotor amps, and start time – motor thermal damage curve)


6. For a 1000 kVA, three phase transformer with a 480 V secondary, what is the maximum 480 V fault current? (the biggest mistake most people make is to think you need a computer for a fault study. Just take the full load amps divided by the transformer impedance in percent – in this case 1200 A (IE 1.732/1000) divided by .0575 – 5.75% impedance being sort of “standard” for this size transformer)
7. For a single phase, 120 V circuit that is 200 feet from the breaker to the load, what is the voltage drop if the load current is 10 A and the cable resistance is 10 ohms per 1000 feet? (the trick here is to recognize that you need to double the distance because it is single phase – a 40 V drop is not good – beware most 120 V power circuit s over 100 feet)
8. What is the sine of 30 degrees? (duh, 0.5 – this question is to see if the guy/gal ever has really worked a lot of math problems)
9. For 4-20 mA circuits, should the cable be shielded, and if so, how should the shield be grounded? (yes, to prevent electromagnetic interference to which these low level signals are susceptible – ground it at one end because if you do at two ends and there is a ground potential difference you create a circulating current which can induce an unwanted signal on the circuit. This is the simple answer with umpteen degrees of variation based on conditions. We just had one this week where the single shield ground became loose and a critical signal became erratic and unreliable)
10. For the given cable what is the conductor size, What is the voltage class? And What else can you tell? (for this one I give the interviewee a piece of cable and ask the questions. If he ahs spent any time around cable the first thing that he will do is rotate the cable because most of this information is printed in plain English on the jacket. If he doesn’t, then he is probable an academic type. The correct is “pretty damn big medium voltage cable” because it is a 2000 kcmil 15 kV cable which is not often encountered, 500 kcmil to 750 kcmil being the largest practical thing for most electricians to pull. You can tell it’s medium voltage by the insulation thickness and the shield.

Attitude is everything – best of luck. For more on power stuff, there is always

http://www.joepower.com

 

[peebee]

joepower, I agree that all your questions are central and critical to the job we do. However, unfortunately, I would expect most recent grads to get a top score of 1 or 2 points on your test. Even worse, I know plenty of engineers with 3 years of "experience" (mostly spent drafting) that wouldn't do much better.

Just curious, Armen, how many answers did you know off the top of your head? Did you get any training in these areas? My guess is that the few power classes you had dealt with transformer & motor theory, and maybe included one or two short circuit calcs. Nothing regarding practical construction methods or NEC. Am I right?

 

[SidiropoulosM]

Most of these questions are answerable only by people who work in design or construction. A high voltage transmission planning engineer, for example, would get no more than a 2 on this test. I work with many superb engineers who have no knowledge of the National Electrical Code whatsoever.

I don't know why joepower provided all these questions with no knowledge of the position applied for. Also, such specific technical questions are uncommon in a job interview. Broader questions that show a more general understanding are much more common. If you can show this broader understanding and if you show a good attitude and presentation, don't worry about being able to answer specific technical questions. Michael Sidiropoulos

 

[jstickley]

Armen --

I can't think of many interviewers who will expect recent engineering graduates to have all the detailed technical knowledge and skills that are required for a particular position. Most will expect that your education (assuming it's from an accredited university with a reputable program) has prepared you with the proper background knowledge that you'll need to learn these skills. As such, most interviewers will spend more time asking questions intended to help them assess how you will fit in, adapt to, and perform in the position.

Bottom line -- be prepared by learning about the company and position you're applying for, but most of all, just be straightforward and honest about your expectations, abilities, and personality. If there's one thing that turns me off to a job candidate most, it's when they try to answer everything "just the right way", trying to tell me what I want to hear. If you don't understand what the interviewer is talking about, don't pretend that you do. I'd much rather hear a candidate sincerely tell me "I really don't have a good understanding of everything that will be involved in this job, but I'm interested in the job and am willing to do what is necessary to learn the skills I'll need" than for the candidate to try to talk about it intelligibly when they don't have a clue. Maybe that's just common sense, but you'd be surprised how many times that mistake is made.

Best of luck....

 

[mikhe]

Joepower

Glad to hear some readers found your test somewhat testing, I was starting to get a complex. Its gonna help with my own personal development though...

I am an HV dist engineer that has spent most of my working life in a career more related to the internet bubble and IT. I am now back in power engineering and learning from scratch. I am earning half the salary I used to be on but loving every minute of it. As someone said earlier in this string, the power industry is real and tangible engineering and infinitely more interesting than any particle spinning through the ether.


Armen
Good luck with the job and use this site for support in the future; there's a lot of willing experience out there.

Mike

 

[QCE]

Mike,

Thanks for bringing this thread back to life.

This is not for Armen as he is probably well on his way with a career in the power industry.

This is for new grad engineers and for the people who wrote that people should work in there trained area.

Anyone that takes an engineering degree out of highschool my not necessarily have there life planned out and may rethink there choosen field many times before they graduate but for anyone that persists and finishes an engineering degree from an accredited university, congrats.

You do not have to stick to your choosen field that may have been choosen when you were 18 years old. Choose a field that you will be happy in and try and get a job were you will gain experience in that field. If you have the dedication and smarts to finish your degree you have the dedication and smarts to make it in any field that you choose.

For those of you that did not take an engineering degree. Most university's that offer accredited engineering degrees do not supply the student with hands on experience and therefore it is learned in the field. An engineering degree gives the student the technical background skills to learn hands on skill later on in there career. Therefore a young engineer can switch disiplines quit easily and be successful in what ever they want to do.

Also new grad engineers in general don't know squat about standards and codes. This is an aquired skill.

I was quit honest when I got my job - "I have little knowledge of the power industry but this is what I want to do and I will be very dedicated to my job." I am now in my second year of working for a great company in the power industry. I am quit proud when people ask me why I know so much about electrical engineering when I have a mechanical engineering degree.

I am doing what I wanted to do after my degree even though I choose my disipline when I was a innocent 18 year old that had no clue what I wanted to do but meet the girls and hang out with my friends.

QCE

 

[Bung]

Philosophical question: do you really want to hire the guy who can answer all your technical questions? He is likely to get bored within months of starting, is probably only moving sideways or down (why? has goofed somewhere, been fired, or just wants to move town for perfecrtly valid reasons?) and is probably expecting more money than your are prepared to pay. Or he's after your job Just a thought...

The best thing (IMHO) is to demonstrate some sort of analytical and lateral thinking skills. If you don't know the answer, or the question doesn't make sense, ask questions yourself to coax more info out of the interviewer, work it through from first principles, have a go at analysing the problem. If you don't know the answer, but can demonstrate you have some idea of how to get to an answer, that's a lot better than just looking blank.


Bung
Life is non-linear...