# Data Center Power Factor

Need to figure the power factor for 208v power in our data center. I know that 208v power is more efficient than 120v but I want to figure
the power factor in talking with customers.
So here's how we sell it.
- 20A / 120v power - 20A/ 208v power (assuming 2 phase) - 30A/ 208v power (assume 2 phase) - 60A/208v power - 3 phase.
Power power factor do I use to calculate the wattage any one circuit will run.
I'm using this formula:
A x V = WATTS
How do I calculate this with a power factor for 208v power?
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" snipped-for-privacy@gmail.com" wrote:

Not really.

Not enough info. to calculate power factor.

No. A x V gives you Volt-Amps. You'll need to get the watts figure in addition to this.

Power factor = Watts / Volt-Amps = Watts / ( Volts * Amps )
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Paul Hovnanian mailto: snipped-for-privacy@Hovnanian.com
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If this is for charging purposes, I would concider charging for kVAhrs rather than kWhrs (if that's permitted in your juristiction). That way, you've taken power factor into account and are charging proportionately to the plant you need to provide.
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Andrew Gabriel
[email address is not usable -- followup in the newsgroup]
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Andrew Gabriel wrote:

I couldn't tell what the OP was trying to 'sell'. If its power factor correction equipment, he still needs the Watts vs VA to show the potential savings.
If the system is already near unity (not probable), there's no justification for spending \$\$ on improvements.
On the other hand, if poor p.f. is due to harmonics, the solution needed may be different than slapping caps on the system. That could aggravate things.

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Paul Hovnanian snipped-for-privacy@hovnanian.com
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It sounds like you're saying you want to know the power factor to help you figure out the maximum wattage that can be delivered in a circuit. I hope I'm not stating the obvious, but power factor isn't a function of the source, it's a function of the load.
For single phase, Watts / Volts x Amps will give you the power factor for a load (eg a computer's switching power supply). For 3-phase its Watts / Volts x Amps x 1.73.
You will need to measure a load with respect to Watts, Volts, and Amps. There are several ways to do this. You can Google for them. An easy way, although expensive, is a power meter like the Fluke 434. See http://www.tequipment.net/FlukePowerQuality434.html
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On Sat, 22 Dec 2007 11:12:11 -0800 (PST), " snipped-for-privacy@gmail.com"

Your main issue is "what is the harmonic content on the neutral". If this "data center" is really racks of single phase line to neutral loads you should upsize the neutral at least 2 wire sizes to be on the safe side.
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On Mon, 24 Dec 2007 11:57:28 -0500 snipped-for-privacy@aol.com wrote: | On Sat, 22 Dec 2007 11:12:11 -0800 (PST), " snipped-for-privacy@gmail.com"
| |>Need to figure the power factor for 208v power in our data center. I |>know that 208v power is more efficient than 120v but I want to figure |>the power factor in talking with customers. |> |>So here's how we sell it. |> |>- 20A / 120v power |>- 20A/ 208v power (assuming 2 phase) |>- 30A/ 208v power (assume 2 phase) |>- 60A/208v power - 3 phase. |> |>Power power factor do I use to calculate the wattage any one circuit |>will run. |> |>I'm using this formula: |> |>A x V = WATTS |> |>How do I calculate this with a power factor for 208v power? | | Your main issue is "what is the harmonic content on the neutral". If | this "data center" is really racks of single phase line to neutral | loads you should upsize the neutral at least 2 wire sizes to be on the | safe side.
But what if we run all the equipment directly on line-to-line power, at 208 volts in the typical case of three phase power in a large data center, or at 240 volts where they are supplied only with single phase? There will be no harmonics on the neutral in the 208/120 system because the neutral is not connected. And if each transformer supplying that system is D-Y (as opposed to Y-Y), there are again, no neutral currents upstream.
Now there will be harmonics on the phase lines. But it's less so because there are only 2 load groups contributing to triplens instead of 3 as in the case of the neutral in L-N loads.
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| Phil Howard KA9WGN (ka9wgn.ham.org) / Do not send to the address below |