# I need to go from 480v. To 208v. Using a stepdown transformer to get 200amps ?

Asked Dec 19, 2011, 02:45 AM — 4 Answers
I need to get from 480 to 208 and need 200amps what size transformer do I need?

 Stratmando Posts: 10,426, Reputation: 2515 Uber Member #2 Dec 19, 2011, 05:11 AM
480 X 200 = 96,000 Watts(VA)

I would wait for an answer from TK, Stanforty, or Missouri, or other qualified.
 tkrussell Posts: 9,673, Reputation: 3698 Senior Electrical & Lighting Expert #3 Dec 19, 2011, 06:20 AM

200 Amps x 208 volts x 1.73 = 71.968 KVA

You need a standard size 75 KVA transformer.

Check with your supplier for pricing and what the customer needs are, may need isolation, K rated, Low Temp, etc.

Do need to consider, is the total connected load 200 amps?

Can load a transformer 80% of nameplate rating.

Since your dealing with 480 volts, I assume your an electrician and know all the rules regarding transformers, feeder rating, etc.
KidChaos (Dec 19, 2011 08:20 PM):   Source:
 soupy909 Posts: 2, Reputation: 10 Junior Member #4 Dec 20, 2011, 01:32 AM
Thanks tkrussell
 tkrussell Posts: 9,673, Reputation: 3698 Senior Electrical & Lighting Expert #5 Dec 20, 2011, 06:13 AM

By the way, my calculation includes a shortcut I did not show.

The actual formula is: KVA=I x E x 1.73/1000

KVA = 200 Amps times 208 Volts x 1.73 (assuming 3 phase) and divide by 1000 will result in 71.968 KVA

You can see this and other useful power formulas here:

Useful Formulas

## Check out some similar questions!

480 volt stepdown transformer [ 1 Answers ]

I am currently working on a quote that requires me to add a step down transformer (480vac/208vac). I mostly deal with Low Voltage/Dc Power and do not have a clue about sizing the transformer. I am looking for someone who can help me size it correctly. I know that the source/line voltage is 480vac,...

I am starting a business and have equipment that requires 600Amps/480V/3 phase, but the site I want to rent has only 200Amps/208V/3 phase. Is there anything I can do to get the required power on that site? Any equipment I can buy to achieve this goal? I understand it may be costly. Thank you.

Convert 208v to 480v [ 2 Answers ]

We bought a 20kW UPS that is designed for 480V 3 phase. We are moving to a building that is only wired for 208V. Is there any way to convert 208 3phase to 480 volt 3 phase or will we need to scrap the UPS?

Convert 480V/3Ph to 208V/1P [ 1 Answers ]

I need 80 dedicated 208V/15 amp circuits. How many amps of 480V/3Ph service are required? Thanks for the help.

480v Stepped Down To 120/208v [ 10 Answers ]

If I have a 600A 480v service and I step in down to 120/208, will I have an increase of available amperes at the lower voltage? Or will the amperage remain the same no matter how I change the voltage? Thanks