From the outside, the Arsenal substation in Pittsburgh hasn't changed much – its tan stone walls still blending inconspicuously with the row houses across Liberty Avenue. Inside, however, the substation has undergone almost a complete transformation in recent years.

As part of the ongoing infrastructure investment program, the company basically has rebuilt Arsenal's yard – installing new 138-kilovolt equipment and adding new 345-kV equipment. Coupled with the fact that new underground transmission lines are being built between Arsenal and the Highland substation in Pittsburgh's East Liberty neighborhood, it's quite clear that it's been one of the company's busiest work sites.

"These jobs have involved, at some point, almost every area of the company, from the various crafts people to support groups like Engineering, Legal and Corporate Communications," said Jamie Fitzgerald, project manager for both the substation rebuild and transmission line construction.

Rebuilding of the Arsenal substation began in May 2005. Major aspects of the project included:

• Demolishing two-foot concrete walls inside the old yard.
• Pouring 400-cubic yards of concrete for the 345-kV equipment's foundation – a task that went on continuously for 12 hours.
• Removing the old 138-kV equipment from the roof of the substation's control house.
• Erecting new steel infrastructure.
• Installing new switchgear, breakers, transformers, conduits and cables for both the 138-kV and 345-kV equipment.
• Constructing a 345-kV, gas-insulated system.
• Connecting several thousand low-voltage control cables from the yard to the control house.
• Installing new relays, panels and computer equipment in the control house.

Arsenal's new 138-kV equipment went into service last summer. In February, the company energized the 345-kV equipment at the facility. "It culminated a lot of hard work and was a key step in the infrastructure program," said Pat Conti, manager, Construction Services.

Future work includes:

• Implementing a forced cooling system to ensure equipment reliability during hot weather and increase capacity of transmission lines.
• Installing a 350-megavolt-ampere (MVA) auto-transformer and connecting the 345 kV and 138 kV equipment.

Making a Big Move

The Arsenal work supports a multi-year expansion plan to extend the company's 345-kV "backbone" transmission system. In addition to helping to maintain reliable operations and increase transmission capacity, the expansion plan will provide additional contigency protections to the City of Pittsburgh and the northeastern portion of Duquesne Light's territory.

To supply the 345-kV equipment at Arsenal, the company tapped into an existing underground transmission line running along Liberty Avenue and installed new underground cables into the substation. The existing underground line is encased in an eight-inch steel pipe, which is filled with pressurized oil to insulate the power cables. Liquid nitrogen was used to freeze sections of the oil, creating an "oil stop." When the steel pipe was cut to tap into the line, the frozen sections prevented oil in the remaining 12 miles of pipe from draining out.

Now that the 345-kV equipment has been energized, the next "big" project at Arsenal is the installation of the 350-MVA transformer. The transformer, which is being manufactured in Canada, is scheduled to arrive at the Arsenal substation in May and be put into service by July. "The new transformer will be more than three times the size of the 100-MVA unit that we installed at the Oakland substation early last year," Conti said. "It is designed to improve reliability on our transmission system."

The Arsenal substation eventually will supply power to the 138-kV and 345-kV underground transmission lines being built to the Highland substation. The company began pulling cable through the four-mile underground pipe conduit between the two substations in March.

Construction of the underground transmission lines through the Pittsburgh neighborhoods of Lawrenceville, East Liberty, Garfield, Bloomfield, Highland Park and Lemington is scheduled for completion by the middle of 2007. The second phase of this project calls for building overhead transmission lines between the Highland substation and the Logan's Ferry substation in Plum. The company also will install 345-kV equipment and a 450-MVA transformer at Logan's Ferry.