SKM Power Tools Example Model of a High-Rise Apartment/Condo Complex

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W6SJK

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Hi - does anyone have or know of published examples of an SKM model of a high rise apt or condo building for fault and v-drop calcs? Would consist of hundreds of single-phase 3 wire apartment loadcenters connected to 208Y/120V 3 phase utility service.

My concept was to model say 6 loadcenters per floor with various wire sizes to calculate the max length per wire size, and then lump the remaining NEC demand load into one 3 phase loadcenter, so that the total demand load on the bus riser at each floor is correct.

Thanks!
 
I don't believe anyone would post a study like that. You might find one in a a CBO file that was submitted as part of a plan review for another similar like project in your area...public record.
How would it be helpful for your project other than ballpark guesses.
Is a SINGLE bus riser serving all the apartments ?
 
Single service feeding single plug-in bus riser to a switchboard on each floor.
The fault calc is easy. The problem is the modeling of the system for load flow voltage drop. The components are sized using demand factors per number of units (NEC 220.84) including the bus riser itself. So if I model each apt loadcenter properly to size its feeder starting at the top floor, the bus load of course gets higher and higher as you go down the bus riser and eventually is way over the demand factor calculated load for the bus and service switchboard, giving incorrect voltage drop.
 
I have never done a high rise apt...largest are typically 4 floors with 60 -90 suites per bldg...more of a high rise laying on its side.
I would think the voltage drop calc would start at the bottom and work your way to the top.
Starting at say the BSMT level you have a design load from 220.84 for all units. This load would be be in calc up to first tap on floor 1, lets call it 1600A.
At the first floor you would calculate VD for 1600A on say the 50' of bus duct to get to tap point. Assume using 2000a AL bus duct you lost about 0.4 Volts.
Rinse and repeat at each floor with revised load based on apts above (New 220.84 number) and add VD from floors below.
You can see how you will slowly add up to your worst case at top floor.

I would then calc VD on my longest apt run on each floor ( I use 70% loading ) and add VD at switchboard to get total VD.
My goal was to have no more than 2% VD at apt panel, not sure you can achieve that in a high rise.
 
Right I was thinking of that, which would mean either doing it simply by hand, or maybe using SKM to calc a load flow for just the bus and then do the panels separately. I will need to use different feeder sizes to the loadcenters based on the length since some runs are quite long. Thanks for your input!
 
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