UFES solutions - switchgear upgrades for rapid arc fault extinguishing

Innovative arc flash mitigation in less than 4 ms: the highest possible level of arc flash protection for personnel and equipment, maintenance of secure power supply and the reduction of production stoppages.

The occurrence of an arc fault, the most serious fault within a switchgear system, is mostly associated with extremely high thermal and mechanical stresses in the area concerned. A new, active arc fault protection system is based on the know-how gained from decades of experience with the ABB vacuum interrupter and IS-limiter technology. This latest arc fault mitigation technology now effectively helps to avoid these negative effects if a fault should occur.

The Ultra-Fast Earthing Switch of type UFESTM is a combination of devices consisting of an electronic unit and the corresponding primary switching elements which initiate a 3-phase short-circuit to earth in the event of a fault. The extremely short switching time of the primary switching element in conjunction with the rapid and reliable detection of the fault, ensures that an arc fault is extinguished almost immediately after it arises (Extinguishing time < 4 ms after detection). 

The UFES electronics is available in 2 designs. In this portfolio, the electronic detection and tripping unit (DTU) type QRU1 provides an expandable complete solution with internal light and current detection, which is able to protect small protection areas without any additional devices. 

On the other hand, the electronic tripping unit (TU) type QRU100 uses only external detection units for monitoring of the protected area. In this context, the TU suits ideally for the connection to the ABB arc protection system type REA. Compatible and accordingly tested interfaces are available for this purpose.


24 kV bis 25 kA / 3s
17.5 kV up to 31.5 kA / 3s

ABB UFES Service-Box (up to 24 kV)

The type-tested ABB UFES Service-Box can be used proprietary. It is mounted directly on the switchgear system, taking account of short-circuit strength, and connected by copper bars to the busbar of the switchgear system.

Various installation configurations are possible to ensure flexibility in mounting of the UFES Service-Box at site:

  • Top mounting: for panel width of at least 800 mm
  • End cover mounting: vertical or horizontal, independent of panel width

12 kV / 17.5 kV, up to 50 kA / 3 s 
24 kV, up to 25 kA / 3 s

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