The ABB UFES system relies on a combination of optical detection and mechanical execution.It integrates seamlessly into both new and existing medium-voltage switchgear lineups.
Use a secondary injection test set every 2 to 5 years to verify the overcurrent pick-up thresholds on the QRU. Storage and Handling of Cartridges
The ABB Ultra-Fast Earthing Switch (UFES) is a sophisticated, active arc fault protection device designed for medium-voltage switchgear installations. Unlike passive systems that merely protect against the effects of an arc (such as strengthened enclosures), the UFES is designed to the arc fault almost instantly, ensuring the highest level of safety for personnel and equipment. The system comprises two main components:
The ABB UFES is an active protection device rather than a passive safety feature. It actively creates a safe condition in just a few milliseconds by short-circuiting the fault to ground. From the simple "Service Box" installation to complex digital retrofits with Relion relays, the UFES adapts to a wide range of low- and medium-voltage environments. abb+ufes+manual
Before energizing the high voltage:
The arc is extinguished in less than 4 ms total—20 times faster than standard protection.
The "muscles" of the system. These are vacuum interrupters driven by a micro-gas generator (similar to automotive airbag technology) that drive a grounding pin into a fixed contact in milliseconds. The ABB UFES system relies on a combination
The electronic unit (QRU1) monitors for light (via arc sensors) or current surges.
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The system utilizes the ABB Arc Guard System TVOC-2 or a dedicated REA relay.These devices continuously monitor the switchgear for light flashes and overcurrent conditions.Dual-criteria detection prevents nuisance tripping from ambient light or normal switching arcs. Primary Switching Element (PSE) Unlike passive systems that merely protect against the
The manual provides detailed diagrams for connecting the electronic unit to the device units. This includes:
What is the of your electronic unit? (TVOC-2 or REA?) What is the rated voltage of your switchgear lineup?
In ABB’s UniGear ZS1 switchgear, the UFES is typically integrated via a top-mounted box system. The assembly involves connecting the hexagonal shaft and reducer ring systems to ensure the mechanical linkage aligns correctly with the busbar system.
Whether you are specifying a UFES for a new data center, retrofitting a 20‑year‑old industrial substation, or simply need to interpret the wiring diagram for the QRU1, the manual remains the definitive source. As ABB continues to integrate UFES with digital relays like Relion and with smart sensors, the documentation will evolve – but the core principles (speed, safety, and simplicity) will always be found in the .