Topic: Anyone running miners at 208 volt using line to line? (Read 1007 times)

Hi NotFuzzyWarm.... so I used taps to bring the voltage up to 236, 237 and 238 in each of the phase. My electric guy says that when I start running all the miners in the panel the voltage will drop by 3% so I should be okay. Do you think keeping 238 is a good voltage or should I tap it down to 225? Thanks.

Actually, the panels will do that themselves as you plug in breakers.

The slots are spaced for and fed by phases 1-2-3-1-2-3-1-2-3 etc. so things automatically balance out as you add 1-pole, 1-slot wide  (single phase-to neutral IF a neutral is supplied) or 2-pole, 2-slot wide line-to-line breakers.

That is the general rule for using a 3phase supply to single phase load. You really have to balance it. Distribute the load and connect it to lines 1-2 ; then lines 2-3 and lines 1-3. Provide grounding too for protection.

You can order a distribution panel with a 3 phase supply and single phase load to the manufacturers. They will balance it out according to number of circuits you want.

Silly questions...but these miners are single phase right? So when a 3 phase distribution panel is used it will need to be balanced for single phase? Thanks.

So for the UVR (under volatage relay) for tripping the miners incase of low voltage you think that is an overkill? Thanks.

Not an issue. Since the transformers are not connected in parallel (secondaries tied together and really bad idea) to make the equivalent of 1 big one they don't care what each one is/who makes it/ whatever. Each does its own thing feeding its loads.

Do you think I need to worry about matching the impedance and turn ratios if I am stepping down from 480 to 208 using smaller multiple transformers? The reason I ask is because I am planning to get the used transformers. So it may be difficult to match those ratings. Thanks.

Ah. Ja directly using a transformer meant to deliver 240v would be ideal. Usual problem is the contractor finding a supplier of them.

Ones for 208 are off-the-shelf stock because when used in then normal mixed 208v/120v setup the phase to neutral gives 120v but a 240v transformer gives 168V phase to neutral making it unsuitable for '120v' needs. Since most of your loads are not 120v ya don't care but point is 240v is harder to obtain.

Oh no no no...I meant the taps on the transformers...But I am wondering if I should just go for 240/120 transformer instead of using taps on my 208/120 transformer. If I use taps, I will only have 5% of 208 and that will be 218 using the taps.

A couple of people mentioned that usually lower voltages are problem than higher voltage. So I am just trying to hash out the pros and cons of 208 vs 240 volt.

Taps? As in having a voltage regulator using relays to mechanically switch between them to keep a certain range of voltage out? No no no no. The taps are set on the transformers are set only once - when installed. Set them to as close to 220-230v as ya can and yer done.

For same reason typical stand-by UPS's and especially those with AVR suck is that it takes around 10ms or more for the mechanical relays to operate. During that time the PSU's usually drop out forcing a miner restart.

I remember you mentioning that low voltage/ sag is more of a problem for the machines than the over voltage. Do you think instead of running it on taps its a better idea to just run on 240/120? Do you see any downside of doing that? Thank you.

I wired 12ga feeding each 20A (L6-20) duplex outlet so to power 2 miners. Using a safe 1,500w per miner @ 208 that gives 7.2A per miner and 14.4A total for 2 miners on the outlet. The 14.4A total keeps outlet and breakers happy and fits well with using 12ga wire. Instead of insisting on 10ga, just have them use higher-temp rated wire like used for can lights, is cheaper than 10ga and allays any concerns about 24x7 loads and wire temp.

If you lose a phase the miners fed from it will drop out. If by relay you mean a mains contactor controlled by a voltage/phase monitor to kiil the power - overkill.

Thank you. Now I am just wondering if I should put 2 antminers on 20 amp at 208 +5% taps or put 4 on 30 AMP. I saw someone here on the talk that they are doing it. But I am so surprised that they are succeeding in doing so. I always take the 80% rule for the AMP

Do you have any relays or stuff for the low line sags? Say if one leg goes to the ground in a line to line do you think it will affect the machines? I am assuming since the circuit will be open in a line to line I should be good and the machine won't be damaged due to under voltage.

For the sub panel to the receptacles...do you like 12 gauge wires or the 10 guage ones? I told my electrician to use 10 gauge but he said 12 is enough and said 10 guage will be a little difficult to wire in the receptacles.

I have decided to stay away from the PDU's because they are expensive. So I am just having the receptacles made for each S9...

I was also planning to add TVSS for the surge protection...but those little things are so damn expensive...

Do you also suggest using L6 20P and L6 20R?

Thanks man and let me know your thoughts

Well then ^^ all sounds right and you are on the right track. Especially using the several 480-208 step downs:
1. it of course lets you segregate the loads so when major wiring work needs to be done fewer miners go off line.
2. Lets you run 480 to the point of load when ya then do the step down to 208v (~218v using taps). Tapping high is what I did for our usually 208v xmfrs to give better nominal voltage range vs being at the very low end of it. Fact of life: low line sags are much more common than a high line is... Distributing as 480 allows for using lighter gauge wire for long runs across the building to final transformers and their panels.

Since using all 3 legs for the power the incoming feed being delta or wye doesn't matter. My guess it is wye since you mentioned 277v which is phase-to-center neutral for a 480 wye config. They just have no need to run a neutral from the main 480V panel since you do not use it. That center connection to the utility's transformer will still be the ground point for the feed though so the 4th wire (neutral/ground) will still run from the transformer to your main panel.

sigh. ok some basic info needed (shoulda been said in OP) - where is the mine - North America?
--> Yes, the mine will be in North America

Since you are talking MW power I assume the utility feed is true 3-phase correct?
--> Yes, it will be true 3 phase.

Is the feed Wye, Delta or - not true 3-phase but what is called wild-leg split-phase?
The feed has 3 wires. So I believe it is Delta? Isn't that the case all the time?

What is the line voltage coming in?
Will have around 1 MW of 13KV to 480/277. And from there I will be stepping it down to 208y/120

If >240VAC in getting a new transformer for this?
Yes, getting multiple small step downs of 300KVA for 480 Delta Primary to 208y/120. Will be using taps on the transformer to use around 218 Volts

Does the utility know about this and can their existing service transformer the building handle it?
Yes, they are aware.

Going line (phase) to neut does NOT allow for 'more kW' because the line voltage will be higher than phase-to-phase. W=Voltage x Amps. However - you don't care because the kVA rating of the transformer is what sets max power it will provide.  Pulling 150 KVA at lower voltage phase-to-phase just means slightly current is pulled on each line vs splitting things up using Line-Neutral slightly higher voltage connections...
Thanks, this makes sense

Do notice we are talking KVA here and not KW. They are similar but KVA reflects the rating with non-resistive power loads (feeding PSU's or motors vs incandescent lights or heaters). From what I've seen using my UPS's 1.5KVA is good for a miner pulling 1.25kW max as a derating example.
Thanks, this makes sense

sigh. ok some basic info needed (shoulda been said in OP) - where is the mine - North America?
Since you are talking MW power I assume the utility feed is true 3-phase correct?
Is the feed Wye, Delta or - not true 3-phase but what is called wild-leg split-phase?
What is the line voltage coming in?
If >240VAC in getting a new transformer for this?
Does the utility know about this and can their existing service transformer the building handle it?

Going line (phase) to neut does NOT allow for 'more kW' because the line voltage will be higher than phase-to-phase. W=Voltage x Amps. However - you don't care because the kVA rating of the transformer is what sets max power it will provide.  Pulling 150 KVA at lower voltage phase-to-phase just means slightly current is pulled on each line vs splitting things up using Line-Neutral slightly higher voltage connections...

Do notice we are talking KVA here and not KW. They are similar but KVA reflects the rating with non-resistive power loads (feeding PSU's or motors vs incandescent lights or heaters). From what I've seen using my UPS's 1.5KVA is good for a miner pulling 1.25kW max as a derating example.

Thank you Fuzzy warm...And no I am not brave enough to fiddle with the electricity at all. I am just asking these questions to figure out the best practices and what to deploy.

You're right that in Asia the normal standards are line to neutral 415/240.

One of the electricians I met told me that if I have a 150 KVA transformer and if I do line to line on it then my KW will be less compared to if I had done line to neutral instead. Is this correct? Thanks.

a. HIRE AN ELECTRICIAN/electrical contractor who knows heavy industrial power! This is NOT a DIY project by any means.
b. Asia and Europe distribute 'normal household' power as line-neutral 208-240VAC but no one else does. Any country the uses 110V as 'normal' household power gives us 208 and higher as line-to-line and that is perfectly fine with PSU's.

So your transformer is 208 120 volt?

I am guessing
1) You are using line to line?
2) Would you recommend using 415/240 for a bigger operation or still stick to 208 for like a 1MW operation?

Someone was telling me that I will spend more in wiring if I do line to line than line to neutral.

Thank you.

100KW datacenter on 208V. Works just fine.