UPS ARC FLASH

[Guilhermebr]

Hello.

Case 1- When UPS receives power from the AC 60Hz line side, and supplies power to the AC 60Hz load side, charge internal battery, and the Bypass Switch off.
In this case, for the external short circuit, what is the normal % current contribution? 300% UPS KVA Rating is OK?

Case 2 - In the emergency mode, when AC 60Hz line side off, and the UPS takes power from the battery, for the external short circuit, the current contribution is the same case 1?


GS

 

[dpc]

You need to calculate the worst case and use that. Also, arc flash downstream of the UPS is a different situation than arc flash IN the UPS. For UPS fault output downstream of the UPS, you need to obtain that information from the manufacturer. In addition to the magnitude of current, you need to know how long it will last. Generally the UPS will shut down if the output is shorted (situation is different if there is a static bypass switch, obviously)

 

[cuky2000]

Typically the fault contribution from UPS is around 200% of its rated value.

 

[dpc]

Typically the fault contribution from UPS is around 200% of its rated value.

For how long?

 

[Guilhermebr]

Hi

200% of its rated, dont pickup instantaneous my low voltage Breaker, and there are high incident Energy.

GS