Powering IT Center
- Thread starter judeericn
- Start date
- Status
- Location
- New Jersey
- Occupation
- Journeyman Electrician
By a 5-wire Wye system I'm assuming that you mean a system with an isolated ground. From an installers perspective we haven't installed them in years. Seems that there was a big trend in the 90's to use an isolated ground system for IT equipment. In the past 5 years the IT work that we have done has not had them. A solidly grounded 4-wire Wye system has become the norm. From a design point of view some may feel that the IG system still provides some benefit. Personally I'm not convinced that they are worth the additional cost.
Well I design these for a living and the question is easy to answer. You use a 480 volt 4-wire WYE from the utility, terminate the grounded conductor in the entrance switch gear and leave it there. From there every thing is distributed delta 3-wire to transformers or utilization equipment.
tbonse
Member
- Location
- South Carolina
As a disclaimer, I am going to digress some from your question.
I would say that this really depends on how much and what type of equipment you will be placing in this IT Center. If you will be primarily placing equipment requiring backup power other than servers in this space (i.e. voice switch/ksu/pbx, ethernet switches, CSU/DSUs, Routers, and the like), I would say follow the lead of the telecom industry and use a -48volt distribution system within the room. This type of setup has a higher initial cost, but is beneficial from a reliability standpoint. First, most equipment of this nature comes with the option of a -48v dc power supply (which tends to produce less heat than it's AC counterparts). Second, you can centralize your battery backup in a single location instead of having to place them at the equipment. Third, most of the equipment of this type will have optional secondary power supplies, which can be supplied by different fuses/CBs off of the same or a separate -48v dc power bus. Then you could change out a power supply without having to power down the equipment (just the PS that you are going to replace). Lastly you benefit from the decreased potential for harmonics on your signal wires from AC lines being in close proximity to signal wires. As for powering the rectifiers, I would say 3ph 4-wire WYE, and because the rectifiers are balanced you should not have to up-size the neutal. You would then have a secondary power connection (this time as 120v AC) going to those cabinets that are housing servers and other equipment that do not have a -48v DC power supply option.
If instead you are primarily providing power to servers then I would suggest the 3ph 4-wire WYE configuration, but this time you will likely have to up-size your neutral conductor as most IT equipment operates on 1ph 120v (which means it would connect from 1ph of the 3ph system to neutral).
PS the -48v dc system is normally only feasible in larger systems due to the higher initial cost for the power distribution system.
From the strictly AC standpoint, I would still say 3ph 4-wire WYE especillay considering most modern IT equipment uses a switching power supply and is less suceptible to problems with the incoming power and thus should not require neutral be separate from the bonding conductor (except from the distribution panel to the 1ph equipment).
I would say that this really depends on how much and what type of equipment you will be placing in this IT Center. If you will be primarily placing equipment requiring backup power other than servers in this space (i.e. voice switch/ksu/pbx, ethernet switches, CSU/DSUs, Routers, and the like), I would say follow the lead of the telecom industry and use a -48volt distribution system within the room. This type of setup has a higher initial cost, but is beneficial from a reliability standpoint. First, most equipment of this nature comes with the option of a -48v dc power supply (which tends to produce less heat than it's AC counterparts). Second, you can centralize your battery backup in a single location instead of having to place them at the equipment. Third, most of the equipment of this type will have optional secondary power supplies, which can be supplied by different fuses/CBs off of the same or a separate -48v dc power bus. Then you could change out a power supply without having to power down the equipment (just the PS that you are going to replace). Lastly you benefit from the decreased potential for harmonics on your signal wires from AC lines being in close proximity to signal wires. As for powering the rectifiers, I would say 3ph 4-wire WYE, and because the rectifiers are balanced you should not have to up-size the neutal. You would then have a secondary power connection (this time as 120v AC) going to those cabinets that are housing servers and other equipment that do not have a -48v DC power supply option.
If instead you are primarily providing power to servers then I would suggest the 3ph 4-wire WYE configuration, but this time you will likely have to up-size your neutral conductor as most IT equipment operates on 1ph 120v (which means it would connect from 1ph of the 3ph system to neutral).
PS the -48v dc system is normally only feasible in larger systems due to the higher initial cost for the power distribution system.
From the strictly AC standpoint, I would still say 3ph 4-wire WYE especillay considering most modern IT equipment uses a switching power supply and is less suceptible to problems with the incoming power and thus should not require neutral be separate from the bonding conductor (except from the distribution panel to the 1ph equipment).
- Location
- Massachusetts
tbones I can't help but wonder what qualifications a "Data Translations Technician (telecom)" has to answer the question presented in this thread.
You answer strikes me that you are really not familiar with IT power distribution.
You answer strikes me that you are really not familiar with IT power distribution.
ron
Senior Member
- Location
- New York, 40.7514,-73.9925
I will admit, that one of the bigger shots of my company is a big proponent of this DC distribution concept for the future.
http://www.eweek.com/article2/0,1759,2014774,00.asp?kc=EWNKT0209KTX1K0100440
Many of todays datacenters are 3phase 4wire service entries, then depending on the voltage given by the utility, it is distributed downstream with or without the neutral.
http://www.eweek.com/article2/0,1759,2014774,00.asp?kc=EWNKT0209KTX1K0100440
Many of todays datacenters are 3phase 4wire service entries, then depending on the voltage given by the utility, it is distributed downstream with or without the neutral.
Ron,
I think the DC concept is noble, but today is not practiced by many end users. I think you are aware of two large Colo-Hotels built by Worldcom, one in Caterette NJ, and the other by Dulles airport. Both of these facilities have 6 6,000-amp 48 VDC plants, and 2-750KVA UPS systems. (at least they did when I departed).
As typical the telephone folks use 48 VDC on the switches and transmission equipment, and data folks always use AC supplied by the UPS even though DC is hot in the rack. The data folks use the AC b/c of either ignorance or lack of availabilty DC power option equipment.
What are your thoughts?
I think the DC concept is noble, but today is not practiced by many end users. I think you are aware of two large Colo-Hotels built by Worldcom, one in Caterette NJ, and the other by Dulles airport. Both of these facilities have 6 6,000-amp 48 VDC plants, and 2-750KVA UPS systems. (at least they did when I departed).
As typical the telephone folks use 48 VDC on the switches and transmission equipment, and data folks always use AC supplied by the UPS even though DC is hot in the rack. The data folks use the AC b/c of either ignorance or lack of availabilty DC power option equipment.
What are your thoughts?
Last edited:
tbonse
Member
- Location
- South Carolina
iwire said:
Bob,
I am unsure of your intentions and reason for posting this comment. I have worked in telecom (the primary user/implementer of distributed -48v dc power systems) since 2002. As such I have also been in several different switch sites and also work with equipment that is connected to said style of power system on a daily basis.
If you feel that something I say in this forum is inacurate, I invite you to refute/attack my posting if such is your desire. I, however, kindly ask that you cease and desist attacking me or my character. In continuation, I have also asked you privately to at least spell my name correctly, and I ask you the same again, though now publicly.
Thank You,
Thomas
- Location
- Massachusetts
Thomas I am not attacking you I am simply asking what a "Data Translations Technician (telecom)" does.
As far as 48 volt plants I won't touch that as I have no background with them.
I do have a lot of background in IT room power wiring.
I agree with Dereck, the power distribution is done with 480 Delta feeds.
Can you explain what you mean here?
As far as 48 volt plants I won't touch that as I have no background with them.
I do have a lot of background in IT room power wiring.
I agree with Dereck, the power distribution is done with 480 Delta feeds.
Can you explain what you mean here?
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