Battery Bank Calculations

[Flywheel]

Is there a resource or standard practice for calculating the number and size of batteries for large UPS battery bank installations to accomplish desired ridethrough time, cycling requirements, voltage regulation, frequency regulation, etc.?

 

[stevenw]

I would contact a vendor (ie. Liebert) and have them size the UPS. Typically you need need to tell the the load and how long you want to run on battery, Is you load voltage & frequency sensitive or can it live with a drop. Is their an emergency generator that will start when the power fails ?

 

[ccfowler]

You may want to consider how often and how deeply the battery bank will be depleted and recharged. If the main concern is riding through many relatively brief sags in the normal power supply, the design/selection performance criteria will be very different than if the main concern is carrying the load until a stand-by deisel generator can take over for a situation that is anticipated once every several months.

When dealing with the battery and/or UPS suppliers, be sure to fully disclose all of the conditions that need to be addressed. Battery chemistry and battery structure may be more important issues number of than the number of cells. Recharge rates may be an important issue, too.

Rather than limiting yourself to battery systems, you may want to seriously consider the latest flywheel based systems.

Standard practices provide nice guidelines for design considerations, but most large UPS applications involve specific combinations of needs and available facilities that will heavily influence design/selection decisions. The issues of initial cost, operating costs, maintenance costs, required service life, personnel skill/training requirements, etc. must all be properly taken into consideration.