Introducing 1200-Ampere System VI™ Switchgear

S&C is pleased to announce the availability of System VI Switchgear with a 1200-ampere continuous-current rating. This new rating, coupled with a 25-kA short-circuit rating, expands the role of System VI Switchgear as an economical alternative to metal-clad switchgear and allows it to be applied on larger distribution systems.

The Vista switches are all still rated for 600-ampere capacity maximum. A line-up of gear will generally use a 1200-ampere Alduti-Rupter® Switch in the incoming bay and possibly include a metering section. An air-insulated through-bushing is used to connect the bus to the tank of the Vista® Underground Distribution Switchgear serving the distribution feeders connected to the load-interrupter switch and/or fault-interrupter ways. The 1200-ampere rating is achieved by using dual copper main bus inside the Vista tank. A typical one-line is shown below.

One-line Diagram

Compared to metal-clad switchgear, System VI Switchgear offers a huge price advantage. For example, for a 15-kV line-up as shown above, with a 1200-ampere Alduti-Rupter Switch in the entrance bay, a metering section with provisions for CTs and PTs, and a distribution section with four 600-ampere fault-interrupter ways, is approximately 48% of the price of Metal-Clad Switchgear!

System VI Switchgear requires a much smaller footprint too:

System VI Switchgear: 188„ wide x 44„ deep
Metal-Clad Switchgear: 216„ wide x 96„ deep

And System VI Switchgear offers a variety of important features that compare very favorably to metal-clad switchgear, including:

Easy reclosing. System VI Switchgear can be reclosed simply and easily by turning the operating handle or, if power operated, by pushing a button.
Visible break. System VI Switchgear offers a simpler method for obtaining a visible break. Upon opening the switch, the open gap is easily verified by lifting the window cover.

Metal-clad gear, on the other hand, requires that the user rack out the breaker to achieve a visible break between the bus and the cable. This is one of the most troublesome aspects of drawout gear. It’s when many arc flash problems occur. System VI Switchgear eliminates this hassle.
Grounding. Connecting grounding cables to metal-clad gear requires racking out the breaker completely, inserting a special grounding truck, and then racking it back in place. This operation has all the same problems and safety concerns noted above . . . but doubly so, since there’s a need to introduce an additional device to achieve grounding. System VI Switchgear requires only that the operating handle be moved to the “grounded” position and then the window cover lifted to verify that the cable is connected to ground.
Relay response. The Vista UDS Overcurrent Control incorporates several time-current characteristic curves, and can coordinate with a variety of upstream and downstream devices. If special relays are required, the overcurrent control can be replaced by an external relay. It can also accept inputs from other devices.

The increased rating allows System VI to be used in many applications that previously were feasible only with metal-clad switchgear. The benefit is a substantial reduction in size and cost.