When Progress Energy began construction of its new, 19-story corporate headquarters in downtown Raleigh, NC, there was concern that a massive grid failure could leave its 1,100 employees needed to restore the power system literally in the dark. This concern prompted incorporation of a 2,800-kilowatt generator capable of fully operating the entire building's systems into the facility, allowing the power company to quickly restore power to its customers.

Progress Energy (NYSE: PGN) is a Fortune 250 diversified energy company with more than 24,000 megawatts of generation capacity and $9 billion in annual revenue. The company provides retail electric service through two subsidiaries. Progress Energy Carolinas provides electrical service to a 34,000-square mile area that includes the eastern half of North Carolina, the northeastern quadrant of South Carolina, and the Asheville area in western North Carolina. It provides service to 1.3 million customers and a population of more than 4 million people. The company's other retail subsidiary, Progress Energy Florida, spans about 20,000 square miles in central Florida, including metropolitan St. Petersburg, Clearwater, and the greater Orlando area, and provides electrical service to 1.5 million customers and a population of more than 5 million people.

Like many corporate operations, critical engineering and management functions are housed in the corporate headquarters, located in Raleigh. With data management functions interlinked between the various operating groups, an electrical failure could result in a serious challenge for the company to communicate and to restore power to its own service areas. With these concerns in mind, Progress Energy elected to design a full backup generation system into the new 386,000­square foot building that would be capable of providing enough energy to fully operate all of the building's systems, from HVAC to computer operations.

According to Franz Lang, Progress Energy's facility property engineer, the new building has both a life-safety generator and the standby generator. "The 2,800[-kilowatt generator] is the facility for the building, and the 750[-kilowatt generator] is the emergency generator. The sequence of operation is that the 750 starts first when we have a power loss. Once that's up and running, the second one will get up to speed, make its transfer over on the main switchgear. The emergency [generator] will see normal utility power, even though it is energized by the standby generator. Then [the emergency generator] goes through a timing mode and drops out and the whole building, including the emergency circuit, is taken over with the standby. To meet the requirements by the state and building codes, you have to have an emergency generator first come on-line because it comes on quicker."

Typically the emergency generator must kick in within 10 seconds after loss of power in order to energize emergency lighting and elevator systems so that, if the building needed to be evacuated, it could be done safely. With the standby generator, the full system is expected to come back up within 30 seconds.

Unique to the design of this standby generator is the fact that, at 2,800 kilowatts and 1,800 revolutions per minute, it is the largest and most powerful engine generator set ever built. The generator set is a Detroit Diesel/MTU 2800 DSE. The Detroit Diesel/MTU 2,800-kilowatt diesel engine generator set is powered by a DDC/MTU 20V4000 diesel engine with a unit-mounted radiator. The 20V4000 is a single-block, twin turbo design and operates at 1,800 revolutions per minute. This engine has the capability of producing up to 4,036 horsepower with a displacement of 5,480 cubic inches and a power-to-weight ratio of 5.2 lb/hp. Covington Detroit Diesel, located in Greensboro, NC, provided the system.

Responding to the Need

Covington Detroit Diesel was familiar with the needs of Progress Energy, due in part to a long relationship between the two companies. "In their existing corporate facility, we've got a 1,050-kilowatt Detroit Diesel package that was put in back in 1977 that backs up the life safety for that existing corporate facility," states Danny Smith, generator sales engineer for Covington. "Last year, they decided they wanted to pick up the remaining portion of their existing corporate facility, so they called Covington in and we assisted the owner and their engineers with a design for a turnkey 2-megawatt generator system. We completed that project, and when it came out that they were going to build a new corporate facility across the street, they contacted Covington once again, mainly due to our service capabilities."

Identifying a generator system that would be capable of operating the entire system in a single package was a challenge due to the limited space at the new corporate facility. "To pick up the entire building we would need something in excess of 2,500 kilowatts," Smith recalls. "We decided to go with our 2,800-kilowatt single-engine generator set. The reason they [Progress Energy] went with a single engine rather than going parallel was due to space. Being a downtown corporate facility, as you can imagine, the real estate is very expensive so with the room they had available in the building to put the generator set in, it only made sense to go with a single unit."

In addition to the generator set, Covington provided the ASCO Bulletin 950 Synchropower Generator Control Switch Gear, furnished by Automated Switch Company (ASCO), that allows the generators to pick up the power loading in the building. "We were furnishing the switchgear as well," states Smith. "We can start the engine up, parallel it to the utility, do a soft load transfer, and walk the load over to the engine without the facility ever seeing an outage. When we decide to go back to the utility, we can walk the load back over to the utility and then open the generator breaker so it does have paralleling switchgear to operate the facility either on generator or utility."

While the standby generator is capable of operating the building during a power outage, the challenge of bringing a building smoothly back up to operational capacity was also addressed especially in the air-handling and ventilation systems. "When the supply fans and chillers see a drop in voltage, they automatically shut themselves down," states Lang. "All the fans, pumps, and chillers are on what is known as a soft start. That helps the generator and also helps with your peak kilowatt demand. The fans have variable-speed drives. Everything ramps back up softly. It does not come up at full-load amps at all, so that helps bring the building back up on-line."

Putting a Big Package in a Small Location

Installation of a standby generator that weighs 55,000 pounds and is 25 feet long created a host of design and installation problems. With the limited building space, there was not a lot of additional real estate available for design placement, and concerns regarding noise and fueling all had to play a role.

"Most jurisdictions have noise ordinances, and we had to coordinate that," states Paul Carlson, senior associate with B&A Consulting Engineers of Decatur, GA, the electrical design engineers on the project. "We had to bring an acoustical consultant actually onboard to provide a custom solution to make sure that the sound level is within the requirements of the local jurisdiction. Plus, as a large company, they want to be a good neighbor. They don't want to go ahead and start blasting people as they walk by on the street either. It is inside of a room, with acoustical sound treatment on the intake and discharge, and then we have a super-critical muffler silencer on the exhaust to limit the exhaust noise too."

The noise limits were of concern, especially since both generator sets are exercised each week to ensure startup and operation. "That's one reason for the sound attenuation as a good neighbor," says Carlson. "During normal exercising in the middle of the day, you still don't want to be too much of a bother to any neighbors around. But you want to be able to load it up, bring the generator on and off for testing. You can test it with the building load, which is the best thing to do for an engine during its weekly testing, to burn the gunk out. Diesels get unburned hydrocarbons in the stack if you don't get it up to operating temperature for an extended time to go ahead and clean everything out. The key is to get it to operating temperature at a load that will get the engine exercised."

Another challenge was the installation of fueling tanks to operate the large generator. "It was an issue because the building codes don't permit the fuel storage," states Carlson. "If you do fuel storage, you have to put it inside of a four-hour containment. But we're in a fire district, which local municipalities can declare in terms of its high-hazard area, usually downtown areas in which case they allow no fuel storage. They want to have life-safety generators, so you have to store fuel on-site, so it just means that the jurisdiction has a better hand with which to negotiate with us. In our case, we ended up with an underground fuel storage tank."

With more and more companies facing the challenge of competing in the global market, the ability of their corporate operations to operate on a 24/7 schedule becomes imperative. Installation of generator systems capable of keeping operations functional in the event of power outages or other disruptions will more than likely become a trend in the future. "Companies today cannot afford to be down," says Smith. "If they go down, a lot of their other branches go down because of the data that go through corporate, so it's not just that particular facility that's going down. You may be taking down multiple other sites if that particular facility goes down. In our case, we have approximately 2,400 employees in the downtown corporate facilities, but if you look at all of our facilities, you could be talking big numbers as far as people not being able to continue to work."

LYNN MERRILL is director of public services for the City of San Bernardino, CA.

DE - July/August 2004