3 phase calculations for PDUs in data center

[jotw]

Good evening. On an unrelated note, I just started a remodel today and took some pictures I think you all will get a kick out of. I'll post them when I get a chance.

Alright. I know you all hate to just give answers and would rather give Articles. Unfortunately, I don't find anything relative to this particular installation. And, I think my math is way off. At least I hope it is. I am new to 3 phase calcs.

The installation is as follows:
2 - 40kw PDUs (480V input protected by 80A breaker)
1 - Fire suppression system (120V w/ 20A breaker)
1 - ten ton mini split AC system (don't have elec. requirements yet)

The data center is approx. 200' from the service.

I need help with sizing the disconnect and feeders. Any help is greatly appreciated.

 

[jotw]

the AC requires 15A @ 208V.

 

[BJ Conner]

Server Load

Server Load

Good evening. On an unrelated note, I just started a remodel today and took some pictures I think you all will get a kick out of. I'll post them when I get a chance.

Alright. I know you all hate to just give answers and would rather give Articles. Unfortunately, I don't find anything relative to this particular installation. And, I think my math is way off. At least I hope it is. I am new to 3 phase calcs.

The installation is as follows:
2 - 40kw PDUs (480V input protected by 80A breaker)
1 - Fire suppression system (120V w/ 20A breaker)
1 - ten ton mini split AC system (don't have elec. requirements yet)

The data center is approx. 200' from the service.

I need help with sizing the disconnect and feeders. Any help is greatly appreciated.

All the power that goes into a server room turns to heat. The AC system has to take the heat ( from servers, people and lighting) out of the room.
So besides the 100 KVA for the servers you need about 35 tons of AC. Thats about 60 KVA with a chiller unit having a SEER value of 8.
Data centers have a history of growing. The IT types think they can stick servers in as long as they will fit. Cooling is were a lot of them hit the wall. Essential power is the next place. Good practice is redundant power sources with UPS back up.

 

[ron]

If you have (2) 40kVA PDU's, then the IT load can't grow larger than 80kVA with the installed equipment. Do they want spare capacity? Typcially yes as was mentioned before by BJ.
The A/C electrical load is typically equal to the IT load.
80kVA (IT load) x 2 (for future) x 2 (for A/C to support IT load) + fudge for Admin support areas. Once you know the overall kVA, then divide it by the three phase voltage and divide that by sqrt3, so it will give you the current needed for the service.
So if it were a 480V utility, then maybe a 400A or 600A service, depending on the future.

 

[dbuckley]

Thing I'm going to mention is that data centres are big on harmonic currents in the neutral; you should plan for 200% neutrals.

Other than that, if you've got 2 x 40KW PDUs for IT equipment, that 80KW of IT equipment will need about 30KW average of aircon to get the heat out. That's an average number, which will work for the KWh; the actual load may be as high as the sum of the nameplates of all the cooling equipment.

No UPS protection?

 

[maghazadeh]

Just for Data room equipments, we used to figure 22-to-25 watts/sf, but last several years, we have seen designs figuring upto 200-220 watts/sf. This would be the size of PDU or PDUs.