# Transformer size required

#### ronball

##### Member
I have a customer wanting to know how much power for their Bitcoin mining business.
they had 430 rigs that each use 3.5kw/ph at 240/415 volts.

I think I came up with transfomer being about 6000 amps.

#### don_resqcapt19

##### Moderator
Staff member
3.5 kW per phase does not sound correct.

#### ronball

##### Member
I stand corrected they use 3.5 kw per hour running, not per phase..

#### petersonra

##### Senior Member
3.5 kW per phase does not sound correct.
each computer is hooked to 240 V. 3.5 kw per computer does not sound crazy to me for this type of computer.

430 * 3.5 kw = 1505 kw

#### ronball

##### Member
the 3.5kw/ph was meant to be per hour, not phase.

#### petersonra

##### Senior Member
I stand corrected they use 3.5 kw per hour running, not per phase..
kW is a rate, so kw/hr is not an appropriate unit.

If they are using 3.5 kw-hr per hour, that is the same thing as 3.5 kw per computer.

#### electrofelon

##### Senior Member
Perhaps it would be prudent to meter one of the units......

#### tortuga

##### Code Historian
Assuming you can balance all the 240V L-N loads
I would take the nameplate VA of the units total them up add a 25% continuous factor then divide by 720.51V (416 * 1.732 V)

Side note I call our new standard voltage '416/240' should I be calling it 415/240?

#### LarryFine

##### Master Electrician Electric Contractor Richmond VA
Side note I call our new standard voltage '416/240' should I be calling it 415/240?
The former; it's twice 208/120.

#### tortuga

##### Code Historian
Thats probably why I call it 416/240.

#### tortuga

##### Code Historian
If they really are 3500VA per unit I come up with 2089 Amps:
 Qty​ VA​ VA total​ Amps​ 430​ 3500​ 1505000​ 2089​

Assuming you can balance the load on all three phases.
I wonder what the lead time on a 2000 kVA padmount 416/240 transformer is?
EDIT: I did not add the continuous factor

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