Electrical Calculations Help

A set of useful tools :

http://hto.power.schneider-electric.com/CBT/Apps/Index.aspx

Thank you sir it was very useful

Hint: only one of the compressors will be on at any time and only two of the three motors...

Unless you have a 100% rendundant backup compressor design configuration which is not common in most air systems:

If the system air demand is high enough both compressors would be operating at the same time.

As an entry level EE, don't let your inexperience stop you from asking your co-workers questions on how this is done. If you act like you know how to do this, and screw up, that's a place you don't want to be, as you never will be trusted to make any decisions on your own, (and get the boots out the door). Showing ignorance is not bad when starting out.

That said, you've calculated maximum demand, so you can size the incoming breaker size as well the cable (is future growth required, I would be a pissed off customer if I had to replace/add more cables, panels). What electrical codes are in place for this customer, that determines service entrance wiring type, and size will be determined on is it buried, overhead, in conduit, as thermal heating effects determine this, as well insulation type. Get the correct code book! This will serve as to size the panel. Load breakers are based on each item ampacity, as well the wire size for the breaker selected, as the circuit breaker protects the wire, not the end load connected to it. Motors will require protection contactors, that's where the protection for each motor is done.

Ask your superiors for help, ask real smart questions (and dumb questions will direct them to training you on needed information) during these conversations, as this is what they will judge you on. How sharp are you at "getting it", and interactive questions based on the previous discussions.

Thanks for the advice.My colleagues replied like the same way you did.I didnt understand most of them..Thanks

Yes you are right.

Some times I also feel the same.

Pardon me, but you're wrong Sir; your understanding of an answer doesn't change its relevancy.

If you don't understand the information posted here, that should encourage you to investigate furthermore, not escape to a place where they answer you what you already know.

Yahlasit

But it should be helpful for beginners. The fact that it often isn't speaks volumes about the attitudes of some here, not of those asking questions.

For example, if your response to a question is a smug "Google it!" or belittling their grammar or knowledge, then please don't bother commenting. You're not helping anyone and are wasting your own time. People seek out CR4 to gather any scrap of understanding they can. Share the wisdom, keep the pettiness.

I would disagree.

The OP has stated that he is entry level, looking for advice.... and he will get it because he has told the truth about who he is and what he is doing.. and he will get his leg pulled along the way.. but he will get directions on how to find the answers.... no-one will serve it up for him...

If he is clever enough to find this site, then with a little application and direction, he will find his answers.

Why not? If you don't want to reply to beginners please stay silent only.

"this forum is not that helpful for beginners

i advise you to go to linkedin.com and join electrical engineer group and ask questions there you find more relevant response"

if you do not agree to what i have said just check for how many answers have been provided which will be helpful regarding the originl questions ,

there are comments by people like

hire an electrical engineer

what is your speciality

go to school

this is not a place to solve your homework problems

How have your negative comments added value to the discussion?

They haven't.

I notice that you have posted some very elementary questions, yourself.

There's also a big difference between helping a person with a specific problem, and being asked to provide tutoring to people who can't take the time to perform a proper search themselves.

If you do not like it nobody asks you to stay in touch with CR4 as you very well wrote there are other possibilities.

In fact the basic philosophy at CR4 is to give help NOT to do the work one has to do in order to progress and learn.

If one shows a personal effort to progress and cannot come further one gets help what you can by google-ing yourself get as information it is better to do it by yourself and when you are in difficulties ask for help it will be done.

On the contrary here you can get a lot of help provided that you try on your own with help of Google and other sources to solve the problem and then you send your results.

Many will show you your errors and help you to come to the best result.

One way of acting is not supported by CR4: no one will make the work the other is expected to do!

From an other point of view as you have been already told in school "one learns better through error correction"

The quality of the education is the same, the persons being allowed to get a degree with no aptitude in simple mechanics is what has changed. And universities that used to vet these from the curriculum now are degree mills. This started about 35 years ago, and the engineering guild is filled with these incompetent.

Okkkkkkkkk Qualified engineer Excellent finding.....then why didn't you give the answer for the question

Post #3 told you everything you need to know to do this. You still are wanting someone else to do the whole job.

Have you been to the site where this will be installed? If not, when will you see the end location, you need to see this in order to design this correctly. Especially if this is your first ever task.

What did your mentors tell you that you could not understand? This would be post #6 by you. If you are that lost, then you are in the wrong career. I understand schooling teaches theory, how are you connecting this to the real world. In this case a very simple panel and service entrance. Have you ever touched this type of equipment, every stripped wire and learned the hand skills, and technical installation knowledge to install this. Tour some typical installations with someone technical enough to explain the basic equipments. Ask questions, if you still don't understand, then you are in the wrong career. You need to learn the practicum. Having a degree in EE does not prove you can do this.

Good thing you have good knowledge in English..Keep going.

What did you learn in school?

I mean what courses did you take? What is your specialty?

check this all about electrical calculation

Electrical Calculations Help

I hope this help you.

Thank you sir, I will try to do it myself using the book you have mentioned.

Thank you for the advice i know that I have to do the work alone . i also thank to those few peoples who replied helped me providing hints like where to start like what you told. I admit that I am an entry level i am starting my career i am not born as an electrical engineer like some persons in this forum.

Once again thank you very much for the guidence.

and my english may not be that much good.

Thank you for your support .