3 Phase UPS systems - advantages/disadvantages?

[cmarler_apc]

This was originally posted on APC forums on 3/8/2007

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The advantages of using a 3 phase facility UPS instead of distributed rack mounted UPS's are:

1. Being able to distribute 3 phase UPS power to each rack -
- Gives the IT Data Center manager the ability to plug his dual corded server and network equipment into two different phases of power. Drop a phase coming into the building from utility, and I don't have an outage on my server or network.
- Gives the IT Data Center manager the ability to do phase balancing at the rack/computer level, without the disruptions typically associated with phase balancing of downtime while electricians move breakers around on wall panels or floor mounted PDU's.

2. Compiling all the UPS capacitity in the data center into one place so it can be utilized and distributed more effectively and efficiently.
- Lower equipment cost, lower service contract costs, lower battery refresh costs
- Each rack mount UPS has 10-30% of additional capacity which cannot be used

3. More Rack U space available for IT equipment

Disadvantages
1. Capital budget expenditures vs operating budget expenditures for purchases
2. Sizing of growth is now on the entire data center level, instead of left to the technicians to perform at the rack level.
3. Single point of failure

APC has some great solutions in the Symettra PX product line to address these disadvantages, with 20, 40, 80, 160KW frames to grow into, scaleable by populating with modules to support the capacity required for the immediate here and now power requirements, and redundant hot swappable modules


Does anyone else have thoughts on this subject?

-Chuck