KVA transformer needed for 50 S9 220V

[miner6464]

Hi,
Planning on building a farm. Just ordered 50 S9s 13.5Th (1323W). I’m not sure how to calculate the KVA needed for a three phase transformer for that amount of antminers. Will be using 220V.
Thx for your help.

[momo26]

Hello
you have the apparent power S in volt-amps (VA) is eql to the real uapower P in watts (W), divided by the power factor PF:
S(VA) =  P(W) / PF

where PF is form 0 to 1

so you need the PF to calculate that

[big al]

Power factor should be between 0.95 and 1

You would need a minimum 70kva transformer.

[miner6464]

How many amps should I calculate for an S9 considering it gets hot (35C) in the summer? I'll have pretty good ventilation system.
I'm doing this calculation 1350w / 220V = 6.13amp. Is this right?

[big al]

Amps you want to consider a balanced load. The math works out like this:

1 across phase a-b
1 across phase b-c
1 across phase a-c

Each drawing 6.13 amps per phase. The total amps is 6.13 x 1.732 = 10.62 amps for every 3 miners on a balanced load.

For 51 miners that would be 17 triplets x 10.62 amps = 180.54 amps

So 180 amps flowing on each line and through the main breaker

[64dimensions]

Power factor should be between 0.95 and 1

You would need a minimum 70kva transformer.

I would definitely  check the NEC to see what the cushion should be. Say 80% equals 90kva, probably 100kva unit.

Another decision is what kind of S9 power supply. Since most high quality power supplies can operate from 100-240V inputs, I would try to have an unloaded supply voltage of around 230-235V to further increase the ampacity cushion.

In this kind of installation do people monitor the incoming wire temps?

[big al]

Also whats the plan to deal with the approximately 250,000 btus of heat?

[miner6464]

Dividing the room in a “cool” and “hot” room with the outtake fans going into the hot room. On the cool room I’ll be pushing 11,000 cfm matching the intake of miners. On the hot room having a little more extraction to have a negative static pressure.

[miner6464]

BTW thanks to all of you for your help!