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  1. #1

    conversion from VA to W

    I have a terrible confusion about VA and W when I see them on various co-location centers. What is the equivalence? I have seen “power factor” in some faqs but it’s not clear.

    For example, when a company sells this:

    1/4 rack (11U) with 0.5 KVA

    How many servers with, for example, 200W power supplies fit in?

    And this one:

    *** 1/3 cabinet power outlets are 1 x 10 amp. 1/2 and Full power outlets are 1 x 20 amp.

    I’m confused, any thoughts?

  2. #2
    Join Date
    Feb 2004
    Louisville, Kentucky
    1,083 is a quick explaination of resistive vs reactive loads. Many electric utility companies provide substantial discounts (or penalties) to commercial and industrial power customers based on power factor observations and commitments.
    Jeff at Innovative Network Concepts / 212-981-0607 x8579 / AIM: jeffsw6
    Expert IP network consultation and operation at affordable rates
    95th Percentile Explained Rate-Limiting on Cisco IOS switches

  3. #3
    Join Date
    Aug 2002
    Atlanta, GA
    It's ususally a little easier to just ballpark it. 1U p3 or p4 is 1 amp, 2U or dual xeon 1 3/4 to 2 amps. If you have dual power supplies depending on the design you can use a single value or may need to double the estimate.

    You should leave at least 20% extra so if you are on a 20 amp service you need to have at least 4 spare amps of head room. you also need to plan for switches, firewalls etc.
    Atlanta, GA and Las Vegas, NV. Colocation

  4. #4
    Back when I used to do capacity planning, we used a factor of 60% to convert from VA to Watts. This was based on a switching power supply average that was provided, at the time, by APC.
    *AlphaOmegaHosting.Com* - Hosting since 1998
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