Square D's Power-Zone HVLcc/Model III Packaged Unit Substation is said to offer the smallest footprint in the industry. The small size allows the substation to be installed in locations that were formerly prohibitive. Designed for industrial and commercial applications, this dry-type transformer is available from 75kVA through 500kVA. A newer model will feature 750kVA and 1,000kVA.

The substation's small size allows for the unit to pass through most existing doorways without the need for structural renovations. Total unit weight is less than 6,000 pounds and its 36-in. depth by 62.75-in. width provides a footprint of less than 16 sq. ft. (versus 55 sq. ft. for typical construction for 500kVA transformer) and a floor loading of about 375 pounds/sq. ft.

The product is best for retrofit and high-rise applications requiring increased customer electrical demand as well as spot distribution in new construction. It allows a solution in new or existing areas where the designated space for a substation is restricted. The product incorporates a compact 5kV and 15kV HVLcc switch, dry-type transformer and molded case circuit breaker distribution section incorporated into one integral unit. Compartmentalized construction of the switch prevents inadvertent access. The fuse/cable compartment is isolated from the main bus, and a fault-making grounding switch prevents access to fuse/cable compartment by means of a mechanical interlock. In addition, front, top-located transformer ventilation and HVLcc front access permits installation of the substation against a wall. Finally, a switchgear component of the substation incorporates maintenance-free main and ground switch contacts.

How it works. The HVLcc switch provides a means for switching and controlling 5kv through 15kV class power as well as offering overload protection. The dry-type transformer section (75 through 500kVA) allows this power to be converted to 600V class and sent to a distribution section. The distribution section by the use of molded case circuit breakers and I-line distribution power allows serving more circuits in a particular load area with maximum protection. The I-Line Distribution also offers the flexibility to mount breakers with different numbers of poles and frame sizes across from each other.

How it happened. Square D developed the substation to provide a means of getting a block of power distributed in a much smaller footprint than a conventional load center unit substation. The company wanted to create the ideal substation for retrofit and new construction.

"What makes the Model III unique is that the HVLcc switchgear, a dry-type transformer and an I-Line low-voltage panelboard unit are incorporated into one integrated compact unit," said William Sculley, staff marketing analyst for Square D. "All of the components are manufactured by Square D, so commercial and industrial users can create, renovate or expand using a coordinated electrical substation."

The substation also offers a sealed interrupter (certified for hazardous locations), low maintenance (main and ground switch contacts), and a fault-making grounding switch that prevents access to the fuse/cable compartment, Digital Temperature controller, 1,200A I-Line distribution section provided with back fed main breaker or main lug only. Also, I-Line Plug-On Transient Voltage Surge Suppression (TVSS) units on the secondary provide maximum performance. Square D manufactures all components and the complete unit is engineered and tested as one unit, assuring the user of a fully coordinated design for maximum reliability. Schneider Electric/Square D