# Short circuit current in transformer

When transformer secondary is short circuited, what would be the value of current flowing through short circuited side? Shouldn't it be infinity ideally? If yes, is it only due to large cross-section & highly conductive copper wires that wires don't get melted?

For e.g. suppose I have 1 kVA, single phase, 250/125 V transformer. Now if I short circuit 125V side and set full load primary current i.e. 1000/250 = 4 A in primary then what would be value of secondary current?

• Are you interested in what happens when you operate the transformer within its ratings, or what happens when you exceed its ratings? 4 amps, 250V input into a 1000VA rated transformer is no issue. But if you short circuit the secondary, then apply 250V to the input, you will get a lot more than 4 amps. – Li-aung Yip Mar 17 '15 at 8:07
• Actually I was interested in both the cases. Your explanation is made it clear, thanks. – Deep Mar 17 '15 at 12:54
• To add to your understanding - if you short circuit a transformer and apply full voltage to the input - the current will be limited not just by the resistance and inductance of the transformer, but also by the magnetic saturation of the iron core. – Li-aung Yip Mar 17 '15 at 12:56
• Oh, I kinda forgot the core saturation thing. Thanks :) – Deep Mar 17 '15 at 13:03