I came up with an SCA of 83,619.64 Amps at the Transformer (3Ã˜ Bolted Fault, Infinite Primary, 0.9 of the %Z for tolerances).

Here's the formula I used to acheive the resulting 83619.64 amps:

1: Determine the Full-Load Amperes of the Transformer:

I(FLA) = KVA Ã— 1000 Ã· E(L-L) Ã— 1.73

[ "I(FLA)" = Full-Load Amperes, "E(L-L)" = Line-To-Line Voltage ]

2: Find Transformer's Multiplier:

Mpl. = 100 Ã· 0.9 Ã— %Z

[ "Mpl." = Multiplier, "0.9" figures worst-case scenario tolerance of Impedance percentage ]

3: Determine Transformer's Let-Through Current:

I(SCA) = I(FLA) Ã— Mpl.

So using your Transformer's ratings, here's what it looks like:

1: I(FLA) = 1204.2 Amps

( 1000 Ã— 1000 Ã· 480 Ã— 1.73 )

2: Mpl. = 69.44

( 100 Ã· 0.9 Ã— 1.6 )

3: I(SCA) = 83619.644444- Amperes

( 1204.2 Ã— 69.44 )

Check my math and let me know if there are any errors.

Scott35 S.E.T.

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Scott " 35 " Thompson

Just Say NO To Green Eggs And Ham!