VacuFuse II: The solution to enhanced grid edge reliability

As the severity and frequency of storms are increasing, and as more and more people work from home, outages at the edge of the grid are having a greater impact than ever. Even a short interruption of a few seconds can cause big problems for the end customer.

Repeated disruptions impact customer satisfaction and increase costs from unnecessary call outs. Approximately 70% of overhead distribution transformer fuse operations are classified as nuisance outages, where no other repair work is needed.

The VacuFuse® II Self-Resetting Interrupter (VFII) brings fault-testing technology closer to the end of the grid. As a result, it boosts grid-edge reliability, prevents unnecessary sustained outages, and lowers maintenance expenses. As the VFII operates without the need for batteries or communications it is inherently much more reliable than other fault testing devices.

VFII solves the nuisance outages that occur on overhead lines. When the VFII detects a fault, its vacuum interrupter (VI) will open to interrupt the fault current. If the fault is temporary, VFII will close to restore power. This saves temporary faults from becoming permanent outages and eliminates the site costs otherwise associated with restoration call outs. Therefore, only customers in the section that contains the fault are affected but all others remain on supply.

If the fault is permanent, the VFII will interrupt the fault current, wait up to 45 seconds, test the line, and if the fault remains, it will interrupt the fault and drop open like a standard fuse, thus isolating the fault. After the line crew has cleared the fault, the VFII can be closed back into the cutout, restoring power.

The VFII boasts an Open/Close lever, this lever allows for manual open/closing of the VFII (with a visible open indication – See below). When the lever is moved to the “Open” position, the VI will open immediately. Moving the lever to the “Close” position closes the VI after a short delay (to allow enough power to be harvested) and using the VI to safely perform the close. As the VFII is rated to 6.3kA (Symmetrical) any fault within this will be contained by the VI, allowing a fault make rating to be applied consistently and safely.

As a single-phase device, VFII is intended for use on voltages from 7.2 kV to 15.5 kV. VFII replaces fuses in these locations and, in doing so, reduces outages for customers.

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