Frequently Asked Question

Last Updated 5 years ago

A UPS has its own, internal power source - batteries. For that reason, in case of a power outage, it is possible to still have input and output terminals energized. This brings a risk of feeding the power upstream of the installation and even energize parallel circuits. The line voltage should be isolated while leaving grounding and neutral connected. It is critical to prevent this backfeed from happening for the safety of personnel.


For all the UPSs up to 3kVA that are connected with an input cable, the backfeed protection is implemented in the UPS. Only several professional series connected with terminal (6kVA and above) will be equipped with internal backfeed protection, while most of them will require external device (according to EN IEC 62040-1).


The decision what kind of device to use is left for the electrical technician responsible for the installation. Below are examples of devices with requested characteristics:

ABB France	A75-30	105A
Tianshui	GSC1 (CJX4-d)-8011	80A
Tianshui	GSC1 (CJX4-d)-6511	68A
LS Industrial Systems	GMC(D)-32	45A
Moeller	DILM(C)32-10	40A