A three phase transformer has the following specs 300 KVA 440V. the impedance marked on the nameplate is 3.3% . Determine the available short circuit current at the secondary terminal of the transformer.

Answer 1

To determine the available short circuit current at the secondary terminal of the transformer, we can use the following formula:

Isc = (1 / Z) x Vfl

Where:
Isc = available short circuit current
Z = impedance (in decimal form)
Vfl = line-to-line voltage

First, we need to convert the impedance from percentage to a decimal form. The impedance in decimal form is 3.3 / 100 = 0.033.

Next, we need to convert the line-to-line voltage from 440V to line-to-neutral voltage. Since this is a three-phase transformer, the line-to-neutral voltage is Vfl / √3. So, Vfl = 440V / √3 = 253.27V.

Now, we can calculate the available short circuit current:

Isc = (1 / 0.033) x 253.27V
Isc = 7667.88V

Therefore, the available short circuit current at the secondary terminal of the transformer is approximately 7667.88V.