How many amps....

[Philippine Mango]

Typically speaking, how many amps does a computer use? What about a file server with standard desktop drives? Scsi drives? What I'm wanting to know is how many systems or drives or what ever would 18amps support? Looking to upgrade my power outlet to support a UPS that supports Nema 5-20R sockets as a Nema 5-15R is clearly not enough.
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[Fullmetal Chocobo]

Originally posted by: Philippine Mango
Typically speaking, how many amps does a computer use? What about a file server with standard desktop drives? Scsi drives? What I'm wanting to know is how many systems or drives or what ever would 18amps support? Looking to upgrade my power outlet to support a UPS that supports Nema 5-20R sockets as a Nema 5-15R is clearly not enough.
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My dual Xeon machine had 21 fans, 11 hard drives, two power supplies (600 + 500), a 6800GT OC video card, two Intel Xeon 2.66GHz processors, and it was using about 3.73 amps @ 120 volts... Here is the full list

 

[Operandi]

A PSU will APFC would be a great benefit to reducing AC power draw.

 

[Philippine Mango]

Originally posted by: Operandi
A PSU will APFC would be a great benefit to reducing AC power draw.

are you sure?

 

[Mark R]

Originally posted by: Operandi
A PSU will APFC would be a great benefit to reducing AC power draw.

Not power, not significantly anyway, unless you take the opportunity to get a PSU that is also high efficiency.

However, AC current will be reduced greatly by the presence of PFC.

A PC with non-PFC PSU which is drawing 250 W from the mains will typically need about 3.0 A @ 120 V.
The same PC with a PFC PSU would also use 250 W, but would only need about 2.1 A @ 120 V.

Running costs in both cases are roughly the same (you are billed for the Watts used, not Amps) - but the PFC PSU puts less strain on the wiring and breakers - so you can run more PCs per circuit. Similarly, a PFC PSU will put less stress on a UPS system.

 

[pcgeek11]

A PC with non-PFC PSU which is drawing 250 W from the mains will typically need about 3.0 A @ 120 V.
The same PC with a PFC PSU would also use 250 W, but would only need about 2.1 A @ 120 V.

Watts = Volts X Amperes

3A X 120V = 360W

2.1A X 120V = 252W

 

[Navid]

Originally posted by: pcgeek11

A PC with non-PFC PSU which is drawing 250 W from the mains will typically need about 3.0 A @ 120 V.
The same PC with a PFC PSU would also use 250 W, but would only need about 2.1 A @ 120 V.

Watts = Volts X Amperes

3A X 120V = 360W

2.1A X 120V = 252W

What Mark R is talking about is RMS voltage and RMS current.

In that case, the formula is
Watts = RMS Volts X RMS Amps X Cos (Theta)
where Theta is the phase between current and voltage.

When the two are almost in phase (PFC), Theta is 0 because of the correction of power factor, the power factor or Cos (Theta) is almost 1, so the current is minimized for the same power.

Edit:
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/powfac.html

 

[SuperNaruto]

Originally posted by: Philippine Mango
Typically speaking, how many amps does a computer use? What about a file server with standard desktop drives? Scsi drives? What I'm wanting to know is how many systems or drives or what ever would 18amps support? Looking to upgrade my power outlet to support a UPS that supports Nema 5-20R sockets as a Nema 5-15R is clearly not enough.
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nema 15 is enough for 2 dual screen desktops.. but how many drives do you have, etc..

you probably need a higher va ups.. the apc 1500 one is the max on the 15amp.. i dont think there are anything larger.

 

[pcgeek11]

navid,

I understand that...

But, What I was pointing out for the purposes of the OP this is really splitting hairs as it isn't going to make one iota of difference that he will see in home realistic usage. For that standard generic power ( watts ) or ( VA ) will play more into account. Unless he is doing something really exotic a standard home breaker would be able to handle anything that will be thrown at it. Of course I wouldn't plug my PC into the same circuit as a heater or one that is supplying power tools etc either. As for the NEMA 15 ampere or 20 ampere plugs ... If you have a single plug drawing more than 15 amperes going to one PC you have a real problem.

APC has some really good UPS' with NEMA 15 ampere plugs that will work just ducky. There is a big difference between an exellent UPS and extreme overkill.

pcgeek11

 

[Seekermeister]

According to PowerChute, my computer is currently using about 200 watts. That comes out to about 1.67 amps.

 

[imported_goku]

Originally posted by: SuperNaruto

Originally posted by: Philippine Mango
Typically speaking, how many amps does a computer use? What about a file server with standard desktop drives? Scsi drives? What I'm wanting to know is how many systems or drives or what ever would 18amps support? Looking to upgrade my power outlet to support a UPS that supports Nema 5-20R sockets as a Nema 5-15R is clearly not enough.
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nema 15 is enough for 2 dual screen desktops.. but how many drives do you have, etc..

you probably need a higher va ups.. the apc 1500 one is the max on the 15amp.. i dont think there are anything larger.

Lol, yeah they've got larger alright, APC Smart-UPS 2200AV on a Nema 5-20R , thats the standard nema 5-15 plug but with a "T' on one tip, and then Smart-UPS 3000AV nema L5-30R which are circular. I haven't looked at UPS' in a while but I can tell you that once you go higher end, they start to come in 200V+ versions instead.

Hey, since we're here, why do the UPS units that support higher voltages have much poorer battery life? (The ones that input 200V+ but output 120V or out 200v+)?