Short-circuit calculation at load powered from the UPS

[Marijo Ha]

How to calculate the output current of short circuited UPS with 230 V a.c. output?
What I need to find is the value of a minimum 1-phase short-circuit current Isc min at load to be able to choose the appropriate fuse. Could someone explain how to calculate this for a simple circuit with 100W load, 100m loop and with 10kVA UPS? What data need to be known for the UPS? Do I need to observe the upstream part of the power line all the way from the transformer / generator to the UPS or I could only take the UPS into account as the only power source?

thanks

[knightrider]

How to calculate the output current of short circuited UPS with 230 V a.c. output?
What I need to find is the value of a minimum 1-phase short-circuit current Isc min at load to be able to choose the appropriate fuse. Could someone explain how to calculate this for a simple circuit with 100W load, 100m loop and with 10kVA UPS? What data need to be known for the UPS? Do I need to observe the upstream part of the power line all the way from the transformer / generator to the UPS or I could only take the UPS into account as the only power source?

thanks

Hi Marijo,

Short circuit current magnitude at the load side of an UPS can be found simply from the UPS output capacity.
Typically the magnitude is about two times of UPS output current, no matter how big the magnitude of short circuit current on the upstream side of the UPS.
But, you better consult the UPS manufacturer for confirmation.

Regards.