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Posted by essenz on June 1, 2007, 9:32 pm
I am retro-fitting a small 1600sqft datacenter with one or two Liebert
units (480V 3-PH).
Can anyone tell me the realistic power draw of these units when in
full operation mode?
I will either be using a 10-ton or 20-ton unit.
Alot of people have been telling my that rule of thumb is 1KW per 1
ton, so a 10-ton Liebert should draw 10KW of power.
If my math is right, a 10-ton Liebert pulling 10KW while in operation,
would be pulling approx 12amp per phase.
480V x A x 1.732 = 10KVA, so A = 12
The reason why I bring this up is because I was talking to the
buildings electrical contractor about the power feeds to the space,
which is 200amp 480V 3-PH. I mentioned a single 10-ton Liebert, and he
said he usually wires those as a 60amp 480V circuit - which seemed
overly high? 60amp breaker, when your only pulling 12-15amps per
phase?! I know there can be startup surges, but 60amp seems really
high.
Any thoughts?
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Posted by on June 1, 2007, 9:55 pm
>I am retro-fitting a small 1600sqft datacenter with one or two Liebert
>units (480V 3-PH).
>
>Can anyone tell me the realistic power draw of these units when in
>full operation mode?
>
>I will either be using a 10-ton or 20-ton unit.
>
>Alot of people have been telling my that rule of thumb is 1KW per 1
>ton, so a 10-ton Liebert should draw 10KW of power.
>
>If my math is right, a 10-ton Liebert pulling 10KW while in operation,
>would be pulling approx 12amp per phase.
>
>480V x A x 1.732 = 10KVA, so A = 12
>
>The reason why I bring this up is because I was talking to the
>buildings electrical contractor about the power feeds to the space,
>which is 200amp 480V 3-PH. I mentioned a single 10-ton Liebert, and he
>said he usually wires those as a 60amp 480V circuit - which seemed
>overly high? 60amp breaker, when your only pulling 12-15amps per
>phase?! I know there can be startup surges, but 60amp seems really
>high.
>
>Any thoughts?
What are you trying to do, save some pocket change on the
wiring ? Do what he says. He has done it before, you haven't. The
unit's not going to consume any added power because the wires feeding
it are heavier duty.
--
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Posted by on June 1, 2007, 11:43 pm
> I am retro-fitting a small 1600sqft datacenter with one or two Liebert
> units (480V 3-PH).
>
> Can anyone tell me the realistic power draw of these units when in
> full operation mode?
>
> I will either be using a 10-ton or 20-ton unit.
>
> Alot of people have been telling my that rule of thumb is 1KW per 1
> ton, so a 10-ton Liebert should draw 10KW of power.
>
> If my math is right, a 10-ton Liebert pulling 10KW while in operation,
> would be pulling approx 12amp per phase.
>
> 480V x A x 1.732 = 10KVA, so A = 12
>
> The reason why I bring this up is because I was talking to the
> buildings electrical contractor about the power feeds to the space,
> which is 200amp 480V 3-PH. I mentioned a single 10-ton Liebert, and he
> said he usually wires those as a 60amp 480V circuit - which seemed
> overly high? 60amp breaker, when your only pulling 12-15amps per
> phase?! I know there can be startup surges, but 60amp seems really
> high.
>
> Any thoughts?
Yeah, get the manufactures specifications, follow them and quit guessing.
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Posted by Bennett Price on June 2, 2007, 12:54 pm
See page 24 of
www.liebert.com/assets/products/english/products/env/ics/60Hz/tech_dat/acrobat/sl_18510.pdf
essenz wrote:
> I am retro-fitting a small 1600sqft datacenter with one or two Liebert
> units (480V 3-PH).
>
> Can anyone tell me the realistic power draw of these units when in
> full operation mode?
>
> I will either be using a 10-ton or 20-ton unit.
>
> Alot of people have been telling my that rule of thumb is 1KW per 1
> ton, so a 10-ton Liebert should draw 10KW of power.
>
> If my math is right, a 10-ton Liebert pulling 10KW while in operation,
> would be pulling approx 12amp per phase.
>
> 480V x A x 1.732 = 10KVA, so A = 12
>
> The reason why I bring this up is because I was talking to the
> buildings electrical contractor about the power feeds to the space,
> which is 200amp 480V 3-PH. I mentioned a single 10-ton Liebert, and he
> said he usually wires those as a 60amp 480V circuit - which seemed
> overly high? 60amp breaker, when your only pulling 12-15amps per
> phase?! I know there can be startup surges, but 60amp seems really
> high.
>
> Any thoughts?
>
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Posted by Tony on June 2, 2007, 1:59 pm
>I am retro-fitting a small 1600sqft datacenter with one or two Liebert
> units (480V 3-PH).
>
> Can anyone tell me the realistic power draw of these units when in
> full operation mode?
>
> I will either be using a 10-ton or 20-ton unit.
>
> Alot of people have been telling my that rule of thumb is 1KW per 1
> ton, so a 10-ton Liebert should draw 10KW of power.
>
> If my math is right, a 10-ton Liebert pulling 10KW while in operation,
> would be pulling approx 12amp per phase.
>
> 480V x A x 1.732 = 10KVA, so A = 12
>
> The reason why I bring this up is because I was talking to the
> buildings electrical contractor about the power feeds to the space,
> which is 200amp 480V 3-PH. I mentioned a single 10-ton Liebert, and he
> said he usually wires those as a 60amp 480V circuit - which seemed
> overly high? 60amp breaker, when your only pulling 12-15amps per
> phase?! I know there can be startup surges, but 60amp seems really
> high.
>
> Any thoughts?
>
I don't see why would you ask some thing like that
just look up manufacture tag and in most cases
you will find they recommendation isn't that simple
or literature that comes with unit.
This units almost always have two compressors
and they also have heaters depend on model
so little extra power doesn't hurt but less will.
Tony
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