Topic: Anybody with Electricity Knowledge or Server room SET ups HElp!! (Read 2062 times)

Well I have everything running as we speak in a warehouse but I run into another problem, those freaking machines create some much heat the whole warehouse is crazy hot. Any ideas to cool this room??

No problem.  Yup they do.  120V/208V/240V are just standards in reality voltage can vary by as much as 5% and still meet the standard and most power supplies are built tough enough to handle wider swings in voltage.  208V is very common in computer world, most (all?) datacenters are using 3 phase power which means the drops are going to be 120V or 208V.  

Always read the power supply label.  You shouldn't have an issue with modern computer power supplies (ATX) but some other consumer components (routers, cable modem, etc) might be 120V only.

If the sub panel hasn't been run yet I would go with 30A outlets (NEMA L6-30R) as that is the most common plug for high current PDUs.  At 30A (24A derated) you should be able to get multiple rigs per PDU if you want to use PDUs (208V * 24A = 5KW).

Thanks for the great explanation, I guess more worry and also a bit ignorant about the voltage. I really thought that the PSUs will only work with 120 or 240 nothing in between but if you say that the PSU will work with anything in between 120v&240v then the solves the whole problem. Now I will have to tell my buddy to split the 3 phases into 3 single phases 208v and that should be it. SUCH a relief!!!!

It is easy to get 120V from 208V 3 Phase.  The potential between any two phases is 208V.  The potential between any phase and the ground is 120V.  Notice there is no 240V in the diagram.

Most premises either have 120V/208V 3 phase or 120V/240V single phase service (service = the connection to the power grid).  The later is more common in residential and light business units.  It is rare (although I guess not impossible) for a premise to have both types of service.



If you have 3 phase service then your options are 120V or 208V.  Power supplies are more efficient at higher voltage so there is no reason to use 208V.

There is no good way to get 240V single phase from 208V 3 phase.  I didn't say it was impossible but there is no benefit.  Any tiny (<1%) efficiency by supplying the power supplies with 240V vs 208V will be eaten up by the efficiency losses in converting to 240V to begin with plus the cost associated with the install.

If the premises has 208 3 phase service then use 208V.  It really is that simple.

So once you accept you will be running at 208V it just comes down to how will you make the connection.

If you have enough 208V single phase outlets then simply plug the devices into the outlets directly and save the cost of the PDUs.
If you have some but not enough 208V single phase outlet then get enough 208V single phase PDUs to "share" one outlet with multiple devices.
If you only have 208V three phase outlets* then have an electrician install a sub panel to separate the 208V 3 phase branch into three 208V single phase drops with outlets.

* You can also get a PDU designed for 208V 3 phase but they are very expensive.  Unless you are absolutely sure it is necessary I would just have electrician install the needed single phase outlets.



The PDU isn't changing the voltage from 240 to 120.  A PDU is just a fancy powerstrip. 120V in = 120V out, 208V in = 208V out*, 240V in = 240V out.  Most computer electronics have a universal switching power supplies which can accept an input of anything from 110V to 240V.  If you are using a 240V circuit you are powering the devices at 240V regardless of if you use a PDU or not.  There is a different outlet for 120V and 208V/240V but that has nothing to do with a PDU.  

* The one exception (kinda) is 208V 3 phase PDU.  No computing equipment runs on 3 phase power so a 208V 3 phase PDU separates the three phase input into three single phase outputs.  The voltage isn't changing though just the going from three phase to single phase. 

   
A PDU is a power strip.  Would you buy a power strip with 12 outlets and then connect one lamp to it?  Why not just plug the lamp into the wall outlet the power strip is plugged into.

Nope that would be a UPS.  PDU is a fancy power strip. It has nothing to do with battery backups.

Sorry for saying it's won't work. It's will work but that PDU is not necessary.
Not complicated, just ask the electrician to pull 240 v line from panel.

What do you want with a PDU anyway?

It is only of use when you have frequent brown/blackouts in your area.

You then need to hook up your router to a PDU too, otherwise it wont help.

Keep in mind some PDU prices are quoted without the battery.

Generally, a PDU is wasted money if your power grid doesn´t frequently fail.

Well the computers in the same warehouse run at 110V from a line pulled out of the same 3 phase/208v panel, how is that any less complicated than make a 240v sub panel or just run a straight 240v line from the same 3P/208V panel ??

Well, even if you use that PDU, i still won't work.
PDU only for power distribution not converter.

Well the garage where Im planning to install the machines uses 208v 3phases so I dont know if the miners will work with that voltage without a PDU.

I am agree with DeathAndTaxes.

If the problem is the cord type, then just find the cord that the electrician suggest / suit the voltage.
The guy in ewal.net is datacenter man. He love to use similar equipment at home. They even call electrical outlet "PDU".

But in your case, its will be too much to use such expensive PDU only for power distribution.

I thought you needed a special cord to plug a 240 volt system to a regular 110volt device. If thats the case why did this guy go thru so much trouble to just to switch his system to 240?? I was told by an eletrician that cord for 110v are not the same for 240v. Im from South America and we use the same type of cord for 110v and 240v seems like here in America things are a bit different or at least thats what the 3 electricians talked to for the job said IDK.

If you are going to only have one device per outlet there is no need for any PDU.  Just use a power cord with the appropriate connectors and connect the device directly to the outlet.

Well I saw this thread and that is the only reference of any those types of PDUs on the works, so if it worked for him why not.

http://www.ewal.net/2014/02/10/bitcoin-mining-with-240v/

More like i miss something here, why did you choose to use those type PDU?

Well the warehouse owner is a Master Electrician that does most electrical work around my area many years of experience. His panel is 200 amp panel with 3 phases. He is gonna pull from that panel 5 240 volts outlets to feed 5 of those L6-20A PDUs, each PDU will be connect to one Cointerra so will be only using a bit less than 10 amps per PDU. Anything wrong with this idea?? am I missing something??

just to add a few comments:

1) 208V is definitely better. more power per plug, PSU wires carry half the amperage and dont warm up (mostly if 18awg), and the mains wiring also doesnt need to be as thick as for 110V
2) unless the PDU is just handy to you, be careful. those specialised plugs and multi-phase wiring can end up costing a lot more than cheaper alternatives. One of those 3-phase specialty outlets may cost well over $100, and if you use a 3-pole circuit breaker you are looking also well over $100. (a single pole is around $20)

2a)  NEMA L6-30. receptacles are $50 new or easily found used for <$20. They carry 30A (or almost 5kW after the 80% rule), and fit generic receptacle boxes.
2b) Use typical household 20A 110V outlets (NEMA 5-20) to carry 208V, thus allowing you to use extremely common parts and cords.  *this is very much against code, and a ghetto-solution*

And just to wrap it all up for both US and non-US readers I've accidentally found a nice short link showing pretty much all modern configurations available around the globe:

http://www.ccontrolsys.com/w/Electrical_Service_Types_and_Voltages
http://www.ccontrolsys.com/w/Four_Wire_Delta_Circuits
http://www.ccontrolsys.com/w/Three-Phase_Grounded_Delta_Circuits

I just noticed that you now have 6 terraminers instead of 5 in the original post.

Then another cheaper option is to get 240V 3-phase 3-wire with an additional electric meter. 6 miners will form a sufficiently symmetric load that won't require the neutral wire.

But you clearly will need help of an electrician and cooperation from the utility.


Those are the types of service that an example US electrical utility offers that do not require negotiation, just a matter of ordering and waiting for provisioning.

That's only doable with the agreement with your electrical utility. I believe it is called "high leg delta" 3-phase.
No additional transformers are required with the "high leg delta" hookup. But the efficiency difference will be minuscule. There maybe a surcharge from the utility for supplying this old-style, asymmetric power that will negate any efficiency savings.

http://en.wikipedia.org/wiki/High-leg_delta

Anyway, you clearly need to talk to certified electrician and the warehouse owner, because the change to "high leg" may make the rest of the warehouse unsafe.

Unless the utility offers 240V there (which is doubtful), you can't.  Okay, you could get boost transformers to convert to 240V, but the loss in the transformers would negate any small efficiency gain you might get in the downstream power supplies.  Have you examined the efficiency curves for the supplies to see what the efficiency difference would be?

Well this is what I wanna do before I get more confused, I have a warehouse with a panels that has a 3 phase 208v layout. I have 6 cointerras ready to be plug in but i wanna switch to 240 so I can be a bit more efficient. what do i do?

Gotcha.  Yeah that would be unusual.

Should have said 208V single phase from the utility is unusual if not nonexistent.  Certainly the premises can then be wired with 208V 3-phase circuits, 208V 1-phase circuits, and 120V 1-phase circuits.

208V single phase PDU is very common.   A single 3 phase drop is split into three 1 phase drops and a single phase PDU used for each one.   In a datacenter usually racks are 30A or less so it allows you to power three racks using a single drop and three PDUs.

I think Im just gonna buy 3 of this ones

Tripp Lite PDUMV30HV Metered 208/240V 30A 10 ft PDU

http://www.newegg.com/Product/Product.aspx?gclid=CNCZ9MuNr74CFYFQOgodtRsAzg&Item=N82E16812120338&nm_mc=KNC-GoogleAdwords&cm_mmc=KNC-GoogleAdwords-_-pla-_-Power+Distribution+Unit-_-N82E16812120338&ef_id=U27rvwAABTlJ2oNO:20140515234229:s

As pointed out that is a 3 phase device.  Unless your premises is wired for 3 phase power that PDU is useless.   If you don't know then it isn't.

It is a 3-phase device. Maximum output current is in each phase is 20A. 3*20A*208V=12480W.

Basic introduction to 3-phase systems:

http://en.wikipedia.org/wiki/Three-phase
http://en.wikipedia.org/wiki/Three-phase_electric_power

5 Terraminers have 10 power cords, each drawing 2100W/2/210V = 5A.

You can't distribute them evenly amongst 3 phases. The closest is 3+3+4. So it will be drawing 15A+15A+20A. One circuit is at its maximum. Any further asymmetry and they will start tripping the breakers.

It could work if all the Terraminers have perfect power supplies with perfect load sequencing.

3 phase (208V single phase is unusual, if not nonexistent).

35A * 208V * sqrt(3) = 12600W

the specs says 12.6 kWatts / 208 Volts / then its says 60 amps output but 35 input??

P(power) = I(current) x E(voltage)

12600(w)/35(amps) = 360v

then why do they advertise 12600 watts ??

You can't.

You will need 2 30 amp 208V circuits to power those 5 machines.  And a lot of cooling capacity.

Well Im looking to set 5 cointerra miners at a shop using 208 v, some I was looking to get a PDU3VN10G60 which supposedly can feed up to 12600 watts but then when I was reading the specs says that I will only take 35 amps of input.

here is the link

http://www.tripplite.com/sku/PDU3VN10G60/

Can anybody explain to me how this works?? How will I ever put 12600 watts on a PDU that can only take 35 amps??

I would really appreciate any feedback, thanks.

Nico