Deciding the size of alternator & engine of a Diesel Generator

Having recently gone through a similar situation, I would definitely recommend contacting the manufacturer representatives for whatever lines of generators you are considering. They have sizing programs and are usually more than willing to assist you. If you only need a rough size, remember to account for inrush currents into transformers, UPS systems, etc., as well as motor starting.

Bottom line - they are the experts in that field and it's an expensive mistake to have to fix. Get help from the manufacturer's reps.

Thanks for your inputs. I know most of the basics & design parameters. At this stage i can not approach any manufacturers. Thanks a lot once again to you and everyone else who replied to my request.

That is right, any supplier of a generator set will be able to size the equipment.

Important point here is to provide them correct information what you need!

Estimate what equipment you have to run and give them required power. Normally emergency generator is required to provide "life support" for period of time sufficient for all tenants to evacuate, which is about 1/2 an hour. If you are building a UPS (Uninterruptable Power Supply) system then it is different story.

You have to do required load calculations.

Why don't you just build green and be done with it. Constant power can be achieved thru green power. So in theory you would not need a back up gen set and dirty the earth anymore than these other guys' do. Be a leader not a follower

Dear Sir

Please try www.Joilet-europe.com for green power, like Solar PV , Wind power or Hybrid or at the end Diesel Generator.

Regards

MCF

What was it you were trying to convey to me that it would be expensive or that it would be a good Idea?

look up at cummins web site or at Yanmar website .

Adilnasir,

You mention that a part of the building's use is a medical center. This raises some safety concerns that have not been discussed by others on this thread. No matter where you are, I believe that the National Electrical Code in the USA (publication NFPA-70, most recent edition), will give you a lot of help with your specific questions. Look at article 517--Health Care Facilities. It covers sizing the various loads, dividing the loads into Life Safety, Critical, and Equipment branches, time requirements and methods for transferring the loads from the normal source to the emergency source, etc.

If you have to buy this book, it typically costs $70-100, US. However, this expense is well worth the information it contains and can save you much grief and trouble later.

Let us know how your plans go.

--John M.

John has a great point that should not be overlooked. If this generator set will supply loads in a health care facility, be very careful. Get a copy of the NEC, either the most recent or whatever edition your project is under.

You might want to check out this recent similar thread on CR4:

http://cr4.globalspec.com/thread/19075/DG-Set-Selection-Points

Your prime mover (engine/flywheel/windmill/whatever) needs to have a bigger capacity for startup power in certain cases, especially big fans & pumps (read air conditioning units!). As mentioned by others, medical centres have additional requirements, such as on-line UPS's, separate and/or redundant circuitry depending on criticality, etc. Check your country's codes.