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Ultra-Fast Earthing Switch UFES

An innovative arc quenching system provides the highest level of safety for LV and MV systems against the hazardous impacts of internal arc faults

The Ultra-Fast Earthing Switch UFES is a safe and effective combination of specific arc detection relays and an associated arc quenching device consisting of the so-called primary switching elements (PSE). In case of an internal arc fault the arc detection relay trips the UFES PSE, which initiate a three-phase earthing to break the arc voltage immediately. The extremely short switching time of the PSE, less than 1.5 ms, in conjunction with the rapid and reliable detection of the fault, ensures that an occurring arc flash is extinguished in less than 4 ms after its detection.

An active arc fault protection provided by a UFES system increases safety for personnel and equipment to the highest level. The ultra-fast arc mitigation limits the arc incident energy in the working distance significantly, what minimizes the assessed risks evaluated with an arc flash hazard analysis. It maintains a secure power supply and reduces economical loss by production outages to a minimum. In some cases, e.g. in a pressure sensitive environment, an active arc fault protection concept might be the only option to enable a safe use of electrical equipment.


Product range

Ur:   1.4 kV;     Ik: 100 kA
Ur: 17.5 kV;     Ik:  63 kA
Ur:    27 kV;     Ik: 40 kA
Ur:    36 kV;     Ik: 40 kA
Ur: 40.5 kV;    Ik: 40 kA


Key benefits

  • Greatly increased operator safety due to ultra-fast arc mitigation
  • Minimized damage of electrical equipment and environment
  • 98% reduction of downtime and repair costs
  • 20 times faster than standard arc fault protection - reduces pressure level allowing active arc fault protection concepts, e.g. where gas ducts are not applicable
  • Possible reduction of personal protective equipment (PPE) category according to NFPA 70E
  • 0% toxic gases release due to effective reduction of arc duration


Key features

  • Arc flash extinction in less than 4 ms, 20 times faster compared to standard arc protection
  • Arc detection by means of optical sensors and current measurement
  • Available for switchgear ratings up to 40.5 kV and 100 kA
  • Easy integration into new and existing low- and medium-voltage systems
  • Combinable with different arc detection devices, including REA, TVOC-2, Relion or non-ABB devices
  • Available as individual components and fully type-tested switchgear solutions

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