Structural Stability

The fully welded enclosure is constructed of heavy gauge steel for superior strength and durability. For applications in highly corrosive areas, stainless steel enclosures are available.

Exterior Protection

The surface of each enclosure undergoes a multistage chemical cleaning process. A powder coat finish is then applied for superior corrosion protection, durability and ultraviolet protection. This coating system meets the latest revision of ANSI Standard C57.12.28, "Padmounted Equipment Enclosure Integrity," and the EEI Paint Guidelines.

Door Latching System

The low-profile door latch assembly has no protruding handles. The pentahead on the right operates the three-point latch. The pentahead on the left secures the door to the center door jamb. Both pentaheads must be engaged before a padlock can be installed.

The latching system exceeds requirements in the latest revision of ANSI C57.12.28 and the Western Underground Committee Guide 2.13, "Security for Padmounted Equipment Enclosures."

Externally Replaceable Bushings

The 600A bushings on the AIS switch are truly externally replaceable. This feature allows the utility to quickly replace any bushings in the field without disassembling the faceplate. Due to the individualized sub-assembly design, the AIS may be provided with 200A bushing wells in lieu of 600A bushings.

Padmount Interchangeability

The AIS is designed to be pad interchangeable with competitive designs. Base adapters also are available to make the AIS compatible with pads for some live front gear.

Visible Break

Oversized Thermopane windows provide excellent viewing for verification of visible break. The large windows are constructed of heavy-duty, mar-proof double pane polycarbonate. They are easily removed in the shop to provide ready access to switch components.

Confirming the visible break through the AIS windows eliminates the need to move the 600A connectors. (see picture to right)

External Side Operator

An external operating mechanism is housed on the outside of the center compartment and allows linemen to perform switching functions without opening the cable compartment. Each three-phase gang switch is equipped with its own operator. The external operator can be padlocked in either the open or closed position.

A sturdy operating handle is stored in each operator compartment. The padlocking provisions on the compartment doors accommodate the majority of available padlocks.

Horizontal Feed-Through Bushings

Sufficient space is provided for
feedthrough bushings for parking of elbows.

Fusing Flexibility

Fuse versatility was a key design parameter of the AIS in order to utilize existing fuses already approved and in use by the utility and/or to improve coordination with existing fuse systems. A utility using livefront gear can use the same fuses and end fittings in the AIS.

• S&C SMU-20 power fuse
• S&C SM-4Z power fuse
• Cooper type NX current limiting fuse

For S&C fuses, indicator windows are provided for locating blown fuses. Fuse doors are mechanically interchangeable and require only a simple operation, without de-energizing the 600 amp line side, to change in the field from one type fuse to another.

Fuse Access is Safe and Simple

1. Loadbreak elbow must be removed before the mechanical latch can be opened. Parking the elbow insures that the load is safely disconnected.

2. After the elbow has been parked, the latching bail on the fuse door is released.

3. As fuse door is lowered, a springactivated barrier closes behind it to maintain the deadfront integrity of the switch's tap side.

4. When the fuse door is fully opened, the fuse tray is positioned an ample distance from the cables for easy removal of the fuses.

FEEDER ISOLATION does not require movement of the 600A connectors

After verification of visible break, removal of the arrester exposes the load reducing tap plug on back of the 600A connector.

A Chance Multi-Range Voltage Detector may be used to test for line voltage.

The Feeder can then be grounded with a standard grounding elbow.