Sizing Transformer 480V Primary 120V Secondary: ~10A 3-Phase

[Som_P]

480 V primary
120 V secondary.

9 temperature controllers and 2 power supplies coming off the 120VAC

total Amps are ~10A

This is 3-phase. How do I find the right size transformer?

 

[sophiecentaur]

You go to a catalogue and buy one with the right specification. It is the only way to be sure. You will not be able to make one for yourself (if you need to ask this particular question).

 

[Carl Pugh]

Do you require a 3 phase transformer or a single phase transformer?
My guess is a single phase transformer.
How did you calculate the 10A?

 

[sophiecentaur]

It always helps to describe your problem is more depth than you have done. On the face of it, the requirement is relatively low power and it does seem unlikely that you would need 3Phase.
If it is a one-off piece of equipment then there is no harm in going a bit bigger than you think you may need. If you are doing this in hundreds, then the economics of a cheaper and smaller transformer may make it worthwhile to get your estimate more accurate.

 

[alphysicist]

I would suggest using the following formula to calculate the required size of the transformer:

Transformer size (VA) = (Total Amps x Secondary Voltage)/Primary Voltage

In this case, the required transformer size would be:

Transformer size = (10A x 120V)/480V = 2.5 kVA

This means that a transformer with a minimum capacity of 2.5 kVA should be used to power the 9 temperature controllers and 2 power supplies. It is important to note that the transformer size should always be slightly larger than the calculated value to allow for any potential voltage drops or fluctuations.

Additionally, it is important to consider the power factor of the equipment being powered by the transformer. If the power factor is less than 1, the transformer size should be adjusted accordingly to ensure proper power supply.

In summary, using the appropriate formula and considering the power factor, the right size transformer can be determined to efficiently power the equipment in question.