240v over 110v

[Guest]

i hope this category will work for the topic... if it's better suited under a different category please feel free to move it over...

i am currently doing research on setting up a small computer farm for early 2018

i plan on utilizing approximately 65,000 watts approximately

I will have 2000amp service installed during November

my question is to find out if I should go with 240v or 110v

the master electrician who came over to discuss the project with me told me that i will see a savings of 10% to 15% max on my power consumption if I go with 240v instead of 110v since 240v is a lot more efficient

i am finding conflicting information when doing some research about this, some people agree and say 240v will produce a good savings while other people say there is little to no difference between 110v and 240v

i don't know why there are such vast discrepancies over this topic - it should be a yes/no answer... i'd like to think the electrician is correct as he has many years of experience and told me he's worked on other computer farms in the past so i believe when he says there will be a good savings that there will be a good savings

i'd like to know if it will actually be 10% to 15% more efficient? i mean this is pretty significant - it means in less than 2 years the savings alone will be enough to pay for the entire installation/transformer/warranty etc..

does anyone here have experience with larger projects like this and have you switched to 240v? what has been your experience?

 

[USAFRet]

Get multiple recommendations from actual, local electricians. Including and especially from your electric company.
Instead of random people on the internets, who have no idea of your local conditions.

 

[USAFRet]

Does this "65,000 watts" include the necessary cooling for this farm?

 

[Guest]

Get multiple recommendations from actual, local electricians. Including and especially from your electric company.
Instead of random people on the internets, who have no idea of your local conditions.

thanks....

i have already contacted several local electricians

i am asking here in case there is someone who has already gone through this and installed a larger computer farm - they just might have some good advice for me if they come across this posting...

i am about 99% sure I am going to go with 240v but would like to try and gain a bit better understanding of potential savings... it is obviously more efficient but to what degree and what savings is a little fuzzy...

only 1 way to know 100% for sure and that will be after I am up and running for a while....

 

[Guest]

Does this "65,000 watts" include the necessary cooling for this farm?

it does yes... I live in Canada so winter is a lot less power consumption... but yes it does factor in cooling for summer months

 

[USAFRet]

Yes, I believe 240v incoming is slightly more efficient...less transmission losses.
How much depends on your specific config.

Also, what have other people, in your local area, done with a similar build?
You're not the first. Build upon their experience.

 

[InvalidError]

Most PC PSUs are 1-3% more efficient at 220-250V, copper losses in wiring from breaker boxes to racks will be reduced by 75% but those losses should account for only ~1% of power if you sized wiring appropriately, so that's another 1-2% there. Where you may be seeing larger power efficiency gains is the HVAC and UPS systems - larger electric motor and transformer windings are more efficient at higher voltages since they can handle the same power at lower currents. You may gain 3-5% on the UPS and 5-10% on the HVAC there. Overall, 5-7% seems more likely.

Another benefit of 220-250V is that you need half as many circuits to deliver a given amount of power.

 

[Karadjgne]

120v and 240v are the same thing, both single phase. You won't see much if any difference between the 2 as 120v is just 1 leg of a 240v circuit. Now if you wanted to get some real savings, talk to the power company about installation of a 3 phase 120/208 setup. Could probably cut that 2kA service down to 1kA, which is huge in terms of savings. Initially might cost a little more, kA for kA, but a 3p 1kA is cheaper than a 1p 2kA on any given day.

 

[Guest]

Thank you USAFRet

I will try to track down someone local-ish to see what they've done... very good recommendation!

Thing is I live in the country and a good hour away from the closest city - but I do go in to the city a few times a month so dropping by a computer farm in the area is a great idea! I'll just need to track a couple down some how... not sure exactly how to do this but maybe I'll start with the local computer shops to see if they know anyone...

In the meantime maybe someone will come across the posting and share their experience with 240v who's built a small/medium farm...

I have a couple more quotes coming next week and will see what they recommend about the 240v... Will also see if Electric company has any advice too, they are sending over an engineer on Tuesday to evaluate the installation etc..

Will update the thread once i've sorted this one out! much appreciated for everyones advice!

 

[Guest]

120v and 240v are the same thing, both single phase. You won't see much if any difference between the 2 as 120v is just 1 leg of a 240v circuit. Now if you wanted to get some real savings, talk to the power company about installation of a 3 phase 120/208 setup. Could probably cut that 2kA service down to 1kA, which is huge in terms of savings. Initially might cost a little more, kA for kA, but a 3p 1kA is cheaper than a 1p 2kA on any given day.

very interesting! I will research this and see where I get - spending a bit more upfront is certainly not an issue as each 1% savings is huge when using a lot of power..

what would you figure the savings might be in terms of percentages with the 3 phase over the single phase setup?

 

[Karadjgne]

I install 400A 3p services every month in certain stores. When I have to use single phase, it's 600A, just to make up the difference. The loads run around 60-80% of those totals, so @300Ahr for 3p or @500Ahr for 1p worth of 120v. Roughly @30% difference in the amount of power supplied. Not sure exactly how the power company figures it all out, but everything is smaller. Including the electric bill.

 

[Someone Somewhere]

kVA is what matters, not current. kVA required will be almost the same regardless of what voltage you run it at.

I would expect ~75kVA of extra continuous load (considering cable losses, power factor, cooling is extra) to require the utility company to upgrade/split the transformer. That's a lot more expensive than just a service upgrade.

240V 2000A is absolute overkill, though. That's 480kVA.

You realise you're going to be paying at least around $1000 a week in power bills?

 

[Guest]

kVA is what matters, not current. kVA required will be almost the same regardless of what voltage you run it at.

I would expect ~75kVA of extra continuous load (considering cable losses, power factor, cooling is extra) to require the utility company to upgrade/split the transformer. That's a lot more expensive than just a service upgrade.

240V 2000A is absolute overkill, though. That's 480kVA.

You realise you're going to be paying at least around $1000 a week in power bills?

I wouldn't be doing it if I wasn't fully prepared to pay the bills... It will be well over $10k per month...

I am now considering to go with the 3 phase after reading Karadjgne's advice.

Will discuss everything with the technician from the electric company this week and the electrician and see what the consensus is on which setup to go with.

I will update the thread once it's all sorted out - and if I remember I will update again in 2018 once it's all up and running for a while.

Thank you everybody for your help!

 

[InvalidError]

so @300Ahr for 3p or @500Ahr for 1p worth of 120v. Roughly @30% difference in the amount of power supplied. Not sure exactly how the power company figures it all out, but everything is smaller. Including the electric bill.

500A x 120V = 60kW
300A x 208V L-L = 62.4kW

BTW, the RMS current of each leg is 300A/3 * sqrt(3), which is 175A., which is the same ~500A for all three 120V phases combined. Nothing created, nothing lost.

Power companies give companies a discount on 3ph because it reduces their power distribution cost by dumping the burden of maintaining proper phase balance onto the customer - help the grid and the grid helps you back. Customers who go significantly imbalanced end up paying surcharges either specifically for imbalance or 3ph power factor.