Topic: Power supply question 240volt 3phase power vs 1 phase - page 2. (Read 4924 times)

The IBM 2880 looks enticing to me too (240 volt).
 
One reason I have not moved to the single IBM 2880 with the breakout board is that it introduces a 'single point of failure' for all the miners running on that power supply. 
If it goes, "poof" one night all those miners quit working (100% dead).
I'll probably just install a pair of heavy duty 20 amp (120 volt) circuits in the garage this summer and those miners will heat the garage in winter.

Don't waste your money on the EVGA's Phil, come to the dark side. 2880 Virgin Watts await you in the kingdom of 240 volts... 


Sloopy,

I'm not doubting his claim, I was asking if he had come up with any reasoning, since AC input voltage theoretically should not greatly influence DC output voltage, which is why I asked if he measured the output to see if there was a difference.

Do not be so fast to assume Phillip's gear did not have a gain in performance.
If he says it did be more optimistic.
I have seen this first hand and there are examples posted not only on this forum but all over the internet.
It is easily explainable by confirming the unit's were not receiving "enough" voltage and amperage prior to the move
Or
The units have specific design qualities which utilize the new scenario.

Phillip has shown his knowledge of the miner side. Just because he asks a few questions on the 3 phase does not mean he presents data without factual basis.

For a real world example imagine you under power a lot of S3s with a power supply which regulates the output evenly (I say evenly, but it regulates somewhat without bursting into flames across all S3s), even when "overdrawn", IE the 2880. You can load that baby up with significantly more S3's than you should and she happily hums along lowering the output to each. Most of the S3's may run at 400 a couple at 440, one or two at 390, but they run. Performance is impacted.
Remove enough S3's and alacazam, you get 450 and 500 out of your poor little beasts.


Edit for safety:
Do not overload any power supply, it simply isn't safe and most go pop. (Same for any power source, calculate your supply VS your draw, add 20% safety factor)
Power cycle after any significant change to any electronic device
Keep your hands away from anything with live voltage, IE do not connect live wires to miners.

Your Mileage Will Vary, depending on several things.

that is the plan

Hey Phil,

Long story short, all of your PSUs will not be able to use 3 phase, so you will either give them 2 of the phases and a ground, or 1 phase + 1 neutral + 1 ground.  Always go with 2 phases and a ground as you will need less outlets, wire, etc when using the higher voltage that is from 2 of the phases.  

It sounds like you have a high leg delta system, so I believe one of the legs will be 240, off the top of my head I think the other 2 legs will be 208.  I have never used a delta system, they are older and were for supplying extra volts to start motors.  Your a smart guy, grab a multimeter and you will figure it out quickly (just be careful with live wires).  

I am in Europe. At home I have 3x25A 230V splitted to several parts:

one phase
- 3x 16A - for wall sockets (each max. 3680W)
- 2x 10A - for lights
3 phases
- one separate for 5,5kW electric stove

Usually I have simultaneously aprox. 9kW (miners in wall sockets) and also no problem when I work with 5,5kW electric stove.

short term I will be doing 240 volt in house. long term I have to see exactly how his shop is wired.

I would love to have a 30 amp circuit .

His shop is 1 large room around 1200 square feet . It has 16 foot ceilings. 7 cent power. Would be nice to run a lot of gear .

5 evga 1300's could do a lot. Even 4 would be nice.

The gain in PSU efficiency is understandable, but do you really think the higher hashrate was due to the AC input voltage to the Power supply?  Have you checked the DC voltage?

I honestly know nothing about 3-phase, but I would be cautious as to how you split the legs up to convert it to single phase...
Here is an article about using transformers to convert between three phase and single phase: http://carroll-meynell.com/technical-3phase

gear seems to do higher hash rates and less power draw.

Not a lot maybe 2 percent and 2 percent  but that is around a 4 percent improvement.

 My cost to do it was under 150 usd for 2 circuits and  that is  counting 3 good pdus on ebay.

http://www.ebay.com/itm/121380956007?

http://www.ebay.com/itm/121298867226? >>>>>>>>>> he still has some of these.

From what I gathered from a electrician is 3 phase is used in industrial areas and devices have to be split evenly across all three phases.  It can run more efficiently if used properly but for our uses and for the future single phase is best for you.

The PSU will not see a difference as far as the number of phases go, cause it will only see two phases regardless of single or three phase grid feeds.  You are probably better to go with three phase 240V or single phase 240V since its higher voltage.  Depending on Wye, Delta or high leg your voltage from two of the legs of a three phase circuit can be 208V or 240V.

3 phase is generally used for generators. You can use it to mine by looking at the similar diagram.

10 gauge copper is good for 30 amps, 10 gauge aluminum is 25 amps.

Yes, 10 AWG is what is needed for 30A, you're fine at 35'. Your PDU is likely also 30A, but derated (80%) to 24A. I've run my PDUs at 30A without issue, but try to keep them at a max of 27A.

How are you liking the switch to 240v from 120v? 

I got 2 phase in house and finally did 2 circuits into 240volts.

My friend  with cheaper power has ' 240 volts 3 phase'  and runs a lot of heavy machinery in his shop..   those quotes are what he told me.

When I go back to his  place I will bring a meter and figure out what he really has.

In my home the one I wired with 30amp 2 pole breaker to a 30 amp plug is 10 gauge a 35 foot run.  What can 10 gauge handle safely?

  The pdu is fused for 24amps.

   I know 12gauge is okay for a 20amp 2 pole 240 volt.

Is 10 gauge okay for a 30 amp 2 pole 240 volt.  1 single 240 l6-30r plug to a 24amp pdu.  TIA

^that sounds correct. Thats a 30A receptacle, meaning you can load 5.5-6kW on it (208 and 240V respectively, achieving 80% load). It would connect to your breaker panel using a 2-pole breaker (plus GND)

Now if you have a 30A 3-phase, thats a bit different and is quite unlikely to be seen in a residential building. (90% of homes are 2-phase, each at 120V, to allow 240V when running both phases). A 3-phase breaker will only work properly on a 3-phase panel - on a 2-phase panel you would have 2 rows of 240V sockets, and one row of 0V (since its 2 hot lines of the same busbar)

3-phase is generally for industrial, where power is stepped down from a 600V service, giving 3 hot lines, each at 120V or with a difference of 208V between any two lines. You should balance the load across the three phases

If your going from hot <-> hot it will be 208/240v. But thats not a bad thing, unless you absoletely have to have 120/110 skip it. I'll bet all your bronze rated ATX PSUS's or better not older than 2 years will automatically switch and run better with the higher voltage.

Here is a picture of a box my brother in law made up for me, we will hang one of these above each 400A 208V 3-phase panel to have a visual proof of what is being used and how balanced. FYI these meters were $5.08 each off alibaba  (they also require a CT)

I GOT A HOLD  of 3 very nice pdu's

Each is 24 amps 3 wire hot-hot-ground twist lock.

 Price was under 80 for the 3 combined .

so if I make the 3 receptacles correctly I should have 3 balanced pdu's my guess is all the hots are going to be 120.

I am going to have an excess of power for a change.

I will only be using 208V exclusively for miners, so none of the hots carry 120V. There are 5-wire 3 phase pdu setups that also bring in the neutral to allow you to go from phase to neutral to achieve that. I haven't been able to find any of those guys in the high wattage dept at the scrapyards.

okay I think I get it.

Next question  what are each of you hot wires carrying 120 volts?   1.732 X 120 = 208