Special Application for Vista^®

For Use in Metal-Enclosed Switchgear

When an existing metal-enclosed switchgear lineup needed two new feeders and there was only room for one bay, an enclosure was built that matched the others in the lineup, and a unit of Vista Underground Distribution Switchgear was installed inside.

SF6-insulated Vista gear is much smaller than conventional metal-enclosed gear. A typical 25-kV metal-enclosed gear feeder bay is about 52 inches wide. So the two bays usually required for this application would require 104 inches. But one three-way Vista UDS unit can be housed in a bay about 58 inches wide, reducing the space required by almost half.

The new bay was constructed to match the existing lineup in size and color as closely as possible. Inside is a Vista UDS Model 302 with one incoming way and two fault-interrupter ways. The three-pole, group-operated fault interrupters, rated 29 kV, 600 amperes continuous and 16,000 amperes RMS symmetrical short-circuit, feed the new loads.

The Vista UDS unit is operated from a control panel that’s completely isolated from medium-voltage components. The position of each fault-interrupter disconnect-open, closed, or grounded-is easily seen through large viewing windows in the Vista tank. With the disconnect in full view, the operator can verify the open gap and ground cables without having to remove elbows or T-bodies. And by using the optional push-button voltage indicator furnished, the operator can check voltage without ever moving the cables. A door at the rear of the bay allows access to the elbow connectors.