Generator Sizing

Dears,

I am going to size a generator for a MCC of 350KW max demand.Can some one provide any procedure/code of practice to calculate the generator size

 

[dpc]

I suggest you discuss your application with your likely generator suppliers. They will be happy to discuss sizing criteria. Many have software for calculating necessary generator size based on your specific load profile.

One important factor will the largest motor that you will be starting and its inrush current. Also, what level of voltage drop can you live with on motor starting.

dpc

 

[Electrifier]

I have touched various manufacturrers, but didn,t find any comprehensive calculation method. Cosidering Maximum demand, Starting currents, diversity and spare reconsiderations. IF any one have some literature then please send me

 

[Marke]

Have a look at the FAQ page at

http://www.lmphotonics.com

for some comments on gen sizing. Mark Empson

http://www.lmphotonics.com

 

[dpc]

Here is a link which should allow you to download the Cummins/Onan GenSize software. Usual disclaimers apply - use at your own risk.

http://www.adamselectric.com/onan/gensize.html

dpc

 

[johnno]

Here is a basic rule of thumb for generator sizing based on motor starting. The generator should have spare capacity available of twice the size of the motor in order to start it.

For example, a 400 kVA genset can start a 200 kW motor. Once the motor is running, only 200 kVA is spare, so a 100 kW motor is the largest motor that can then be started. If you started the 100 kW motor, you would not be able to start the 200 kW afterwards as there is only 300 kVA spare. Rough, but it works.

What is important though is to properly sequence motor starting. Where possible, get the big motors away first.

 

[Electrifier]

Consideration about diversity and spare availability?

I think diversity for MCC,s is 0,6 of MAX. Demand and spare capacity is 1.2