Majestically situated on 16 acres (6 ha) of land, surrounded by Pennsylvania's rolling hills, stands a vast forest of gleaming steel structures that compose PPL Electric Utilities' newest 500-/230-kV substation. The substation is located just outside the town of Bethlehem, Pennsylvania, in the foothills of the Pocono Mountains (part of the Appalachian Range). When Bethlehem Steel Corp. became one of America's industrial powerhouses of the early and mid-20^th century, this territory was known as the steel capital.

The blast furnaces are silent now, but on the land where steel was once forged, Conectiv Bethlehem Inc. (Newark, Delaware, U.S.) is constructing a gas-fired power plant that is dependent on the substation for connection to the transmission grid.

The construction of this substation was remarkable in three major ways: the time frame, space allotment and safety conditions. Normally, it would take three years to construct a substation of this size. However, the contractor, Henkels & McCoy Inc. Northeast Division Power Operations (Blue Bell, Pennsylvania, U.S.), completed construction in half the time to meet Conectiv's ambitious schedule.

The substation had to be erected on a plot of land that is 15% more compact than the original criteria determined by PPL Electric Utilities' planning department. We had a limited time schedule, and were doing multiple tasks at multiple times. The challenges presented by time and space were heightened by the presence of more than a dozen trades working simultaneously. These trades were laborers (four unions), operators, operating engineers, ironworkers, carpenters, concrete finishers, block layers, electricians, linemen and teamsters. In a perfect world, work would have progressed more systematically, but a variety of trades had to find a way to work together simultaneously.

A Look Back in History

In 1920, eight small electric utilities in eastern and central Pennsylvania joined to form what became Pennsylvania Power & Light Co. From just 115,000 customers, the company grew to 1.3 million in Pennsylvania.

With deregulation in the 1990s opening doors to new opportunities, the old Pennsylvania Power & Light Co. became PPL Corp., a company that generates and sells electricity in key U.S. markets and delivers electricity to six million customers on three continents. PPL Electric Utilities is the subsidiary that delivers electricity to customers in Pennsylvania. The Bethlehem project is the first major 500-kV substation built by PPL Electric Utilities in the last quarter-of-a-century. The last effort was in the early 1970s, when PPL Electric Utilities connected a new 500-kV substation to its existing substation SONET (Synchronous Optical Network).

The Project Begins

Detailed engineering for the main body substation construction began in April 2001, with completion scheduled for October 2002 to coordinate with the completion of the first module at the power plant.

Today the substation consists of two bays of 500 kV, in a breaker-and-a-half configuration; three 500-kV circuit breakers operated as a ring bus; a single bay consisting of a 500-/230 kV, 750 MVA transformer bank; and a 230-kV circuit breaker.

A second phase will expand the 230-kV yard to a four-breaker ring bus to terminate a second 230-kV line and a 230-kV underground circuit from the plant. For this phase, additional engineering was performed from April 2002 until January 2003 (well after the substation is up and running) to allow for more bays and capacity. Construction on phase 2 commenced October 2002, and will be in service by October 2003 to coordinate with the completion of the last module at the plant.

The ultimate substation installation will consist of two transformer banks, each rated 500-/230-kV, 750 MVA; four 500-kV breaker-and-a-half line bays; and two breaker-and-a-half, 230-kV line bays.

Substation Reliability

This new substation is connected to PPL Electric Utilities' existing substation SONET fiber network. Relay meter communication between the substation and the power plant is handled using a fiber (without multiplexer).

Relaying and communications are handled via fiber-optic relaying, both for the Bethlehem Power Plant and the PPL Electric Utilities' system. The fiber loops are redundant and independent using completely separate fiber routing whenever possible. Paths for both primary and backup signals were routed separately. Approximately 140,000 ft (43 km) of OPGW and ADSS control cable were installed to make this connection from the substation to the utility's SONET. All control is performed with redundant programmable logic controllers (PLC) for both 230-kV and 500-kV systems.

Construction and Equipment

The order of construction was as follows: drainage system, fencing, conduit installation and subsurface cable trench, grounding, foundations, transformer foundation, fire wall, oil containment and pond, structure install, electrical bus, control wiring, transformer install, equipment install (breaker and switches), control house work, yard surfacing and roadway.

One huge challenge was that most of this construction occurred right around September 11^th. Much of the essential large-scale equipment went to the World Trade Center for cleanup, so we scurried around to find what equipment we could. We were able to get some equipment from our offices in New England, but we had to wait quite a bit longer to get some other essential pieces.

The transformers, purchased from Peebles Transformers Ltd. (Edinburgh, Scotland), each weighed 316,400 lb (148,053 km) when shipped and 507,100 lb (230,017 kg) when filled with oil and installed. The 36- by 27-ft (11- by 8.2-m) transformers, with a height to the bushing of 36 ft (11 m), were lifted by gantry and placed with a 500-ton (455-metric ton) crane.

Environmental Measures

The substation itself is on a green site (land that is environmentally safe). However, to the south there is a brown field site (formerly Bethlehem Steel) and wetlands to the east, so we had to follow astute environmental measures.

The soil on the substation property has high clay content, resulting in poor drainage. We had to coordinate all drainage facilities with the power plant next door, and direct the substation and the extensive underground network away from the adjacent wetlands.

Digging and excavation took place from September to January. Even though we had a relatively dry winter, the constant freeze and thaw cycle of moisture on the ground resulted in excessive mud. The limitations that accompany cold weather for substation construction only increased the time challenge. We were relieved when work had progressed to a point where we could apply stone surface.

The substation is downwind from the power plant, which caused concern about the exhaust and steam on corrosion, insulation integrity and icing of substation facilities. Special corrosion protection was specified for the structures. We also instituted increased insulation creepage criteria for the electrical equipment and incorporated the selective use of nonceramic insulators and bushings into the design.

Safety Measures

Logging more than 100,000 man-hours with no lost time accidents was an exceptional feat, especially considering the myriad of activity and the confined space.

The key to continued safety success on this project evolves around the successful use of the team concept. All supervisors and employees within the Steel City Substation project work together. Henkels & McCoy's Northeast Division Safety Department performs onsite training. Daily documented toolbox meetings are held and toolbox talks are given when work scope changes or new hazards are introduced. Henkels & McCoy also holds mandatory weekly safety meetings, which are conducted by foremen, supervisors or the safety department.

We had total buy-in to safety on the job site. Our safety department performs unscheduled job-site visits and rarely finds even minor infractions, such as lack of safety glasses or gloves. Each step of the construction brought its own safety challenges. For example, when working on the foundation, there were trenches as deep as 32 ft (10 m). Also during this stage, it was imperative to have someone test daily for unknown gases. Because of the compressed space and varied, simultaneous activity, we had to take much caution regarding heavy equipment and large vehicles. The construction of the three firewalls required the setup of 30,000 lb (13,608 kg) ballards. In April, testing was done from the control house to verify circuits. All circuits onsite had to be made aware and constantly on guard of what was and what was not energized.

Now that the substation is energized, everyone must be a qualified electrical worker to be in the electrical zone. All the trades are required to go through the PPL qualified electrical training.

The fact that we had a constant flow of new employees from multiple trades necessitated continual safety orientation. In addition, the limited winter daylight and the compressed schedule compounded the risk.

Compressed Space

PPL Electric Utilities designed the substation from scratch. The property available was about 15% shy of the space typically used by PPL Electric Utilities' Planning Department. It was a challenge to position everything in compacted space.

Another space-constraint solution was to lay down the equipment in a substation yard a few miles down the road and bring it in as needed rather than to have it here on site where it was constantly accessible. This ensured security and protection from damage.

We carefully analyzed every aspect of space for the specific equipment that would be purchased and arranged so that it met absolute minimum clearances.

As the roadways were developed, we had to anticipate how to get construction and maintenance equipment to the electrical devices without infringing on the electrical clearances. Some roads had to be rerouted in different directions to account for the large turning radius of vehicles.

The 500-kV area required the most forethought because of the larger equipment for construction and maintenance, which required larger clearances. Electrical clearances were reduced to the minimum, while still allowing the maintenance crews reasonable access and working space throughout the life of the substation. We had a tight clearance on the rework of the transmission line tower that tied into the substation. In one instance, we had to set up a pole from the 500-kV line that was 13.5 ft (4.1 m) away, which is pretty close. That was part of the outage and the reconfiguration of the line.

Because of the close proximity with the cogeneration plant that was under construction right next door and using a lot of large-scale equipment, we had to fence the substation prior to equipment installation to protect our equipment; we couldn't afford to have anything damaged because of the time to get it back.

PPL supplied the engineered drawings for Henkels & McCoy to coordinate the work schedule and handle material procurement.

A Successful Completion in Sight

With a new power plant and state-of-the-art substation being completely in-service by October 2003, Henkels & McCoy and PPL Electric Utilities are pleased with the way this project progressed in spite of the head-shaking handicaps of tight time frame, limited space and up wind corrosion.

The most rewarding aspect of this entire project was the safety attitude. Men from the various trades commented that this was the safest project they had been on and thanked us for that.

James J. Collins received a BS degree in business administration from Mansfield University (Mansfield, Pennsylvania, U.S.) in 1986 and joined Henkels & McCoy in 1989. He has more than 14 years of experience in electric transmission and distribution. His positions have included that of apprentice lineman, journeyman lineman, foreman, workweek manager, supervisor of the PECO URD program and manager of the PPL Alliance. Work completed under his supervision has achieved the milestone of 252,000 man-hours with no lost time accidents.

Gail D. McVicker, corporate editor at Henkels & McCoy Inc., has a BA degree in history/education from Syracuse University (Syracuse, New York, U.S.), a MS degree in media technology from West Chester State College (West Chester, Pennsylvania) and a MA degree in journalism from Temple University (Philadelphia, Pennsylvania). She has produced award-winning articles, newsletters and photographs, and is a computer graphics professor at Montgomery County Community College (Blue Bell, Pennsylvania).

Relay, Control and Protection

The relay and control system installed at the Steel City Substation consists of intelligent electronic devices (IED), programmable logic controllers (PLC) and a computer-controlled human machine interface (HMI), all of which are interconnected by a ModBus Plus and Ethernet TCP/IP network.

The IEDs are microprocessor-based relays and power transducers that take field quantities (voltage, current, device status) and perform calculations and actions based on some standard (base logic supplied by vendor) and customer logic (additional functions added to the logic by PPL Electric Utilities' Transmission Control Center [TCC]).

Most device status information is collected by Terminal Input/Output (TI/O) modules. The TI/O modules also include a processing unit that performs time-critical functions.

The PLC performs much of the control function for the substation (breaker control, MOD [Motor Operated Disconnect] control). There are separate PLCs installed in the substation for breaker and substation mod control, Tap Changer Under Load (TCUL) control, and supervisory control and data acquisition (SCADA).

The PLC for the breaker and mod control is actually two pairs of redundant PLCs — one pair for the 500-kV yard and one pair for the 230-kV yard.

• The SCADA PLC collects data from the IEDs and other PLCs and transmits the information to the TCC. Commands from the TCC are received by the SCADA PLC and then are routed to the proper PLC for control action.

• The TCUL PLC collects data from the transformer and performs out-of-step control.

• The transformer is controlled (raise and lower commands) from the TCC through the SCADA PLC. Local control of the transformer is available through the HMI, if necessary.

The HMI computer is the only means of local control for the substation. All local manual control actions (open/close breaker, open/close mod, transformer raise/lower, maintenance switch and blocking switches) are handled by the HMI. The screen of the HMI will usually contain a mimic bus type picture of the substation showing the status of devices and electrical quantities. When control actions are requested, a screen with control switches is shown. All control actions are performed by clicking on the animated control switches. The commands are sent to the control PLCs that send the control to the actual field device.

The HMI also can handle the Permit and Tag or Lockout function for personal safety.

All communications to the substation (telephone, data to PPL Electric Utilities' transmission control center, data to PJM Interconnection and data and relaying to generation site) is by way of fiber optics.