Taking Stock of Backup Power
You've heard a hot tip that your favorite stock is about to tank, so you call up your broker and tell him to sell, sell, sell. But, almost as soon as you hang up the phone, he calls you back with worse news. He can't process your order. In fact, nobody can, because a massive power outage in New York City has completely shut down the New York Stock Exchange.
You’ve heard a hot tip that your favorite stock is about to tank, so you call up your broker and tell him to sell, sell, sell. But, almost as soon as you hang up the phone, he calls you back with worse news. He can’t process your order. In fact, nobody can, because a massive power outage in New York City has completely shut down the New York Stock Exchange. It’s a pretty scary scenario, even for a casual, small-time investor and it used to be the fear that kept NYSE owners up at night. But not anymore. In July 2005, the NYSE unveiled plans for a state-of-the-art backup and emergency electrical system. Designed by Jaros Baum & Bolles Consulting Engineers, the system design not only met the company’s every electrical need, it accomplished those goals within budget, four months ahead of schedule, and without a single minute of disruption on the trading floor.
Backup and emergency power had been a concern at the NYSE for decades, but plans were hampered by the cost restraint of working with an old building plagued by a lack of spare room and landmark building fa%%CBOTTMDT%%ade preservation regulations. Over the years, the NYSE had hired JB&B to brainstorm a number of possible solutions, but all had been rejected as neither economically nor technically feasible. It wasn’t until 1993 that some real headway was made on the problem. That was when a storm in the Northeast flooded large parts of lower Manhattan Island. Although numerous power failures occurred around the NYSE, the building itself was mercifully untouched. However, owners realized that they could no longer risk not having a backup plan. That year, JB&B came back on the job to plan a temporary “roll-up” power generation solution. Working with Con Edison, the New York area power company, they designed a system of portable generators that could be driven right up to the Exchange on flatbed trucks and connected to a permanent emergency electrical distribution point. Con Ed agreed to store and maintain the generators when they weren’t in use. The plan would provide enough power, fast enough, that the NYSE was certain to lose no more than one trading day, no matter the emergency.
But, that was then. Less than 10 years later, the lay of the stock trading land had drastically changed. Instead of calling in trades, more and more stockowners were contacting their brokers online—and expecting instantaneous results. A backup power plan that might take the NYSE offline for even as long as a day was no longer an option. At the same time, the events of Sept. 11, 2001 and the 2003 New York blackout increased concerns about possible future power emergencies and the effect they might have on the NYSE’s ability to maintain its reputation for accurate, fast and professional transfer of funds and shares. It was time to find a permanent solution.
In October 2003, JB&B was once again commissioned to solve NYSE’s emergency power conundrum. To meet their clients’ needs, the engineers had to design an on-site alternative power source that could come online within two years, not disrupt trading activities during construction, and meet a guaranteed maximum price of $25 million. In addition, the project also needed to provide for: the extension of the emergency power to trading functions in four buildings; relocation of a mechanical equipment room; removal of a skylight and creation of a new smoke exhaust system for the trading floors to replace the former skylight’s function; relocation of kitchen exhaust ducts and fans; rebuilding of a domestic/fire water reserve tank room and pump system; relocation of numerous back-of-house areas; and coordination of a new Con Ed vault to supply future electrical needs. JB&B determined that the critical electrical load the NYSE would require was 4 MW, but, because the Exchange mandated an N+1 redundancy, a fourth generator with 2 MW capacity was added to the plan, enabling the system to supply the entire building at an N+1 redundancy and providing an N+2 redundancy for critical trading functions.
The best place to put the generator array was on the roof of the main NYSE building, but the existing trusses weren’t strong enough to support the weight of four generators. Instead, JB&B worked with structural consultants Severud Assocs. to create a 115-ft. bridge that spanned the main building’s roof and attached to the more solid ground of two of the NYSE’s connected buildings. To connect this emergency plant to the existing electrical distribution system in the basement, JB&B decided to eliminate an unnecessary elevator and ran the conduit as a vertical connection through the space.
But, because of a couple of special considerations, it wasn’t enough to simply find a convenient space to locate the new backup power plant. To meet New York City Landmarks Commission guidelines, the new system would also have to be invisible from the main building’s fa%%CBOTTMDT%%ade and, to meet city building codes, it would also have to be relatively soundless. At the same time, the bridge could only support 360 kips, but each generator weighed 60,000 lbs. by itself, leaving very little excess support for the acoustical enclosures needed to cut sound. To solve these problems, JB&B worked with architects Perkins & Will to create compact and lightweight enclosures and specified a design that set the whole power plant towards the back of the roof to avoid being visible from the fa%%CBOTTMDT%%ade. In addition, P&W ingeniously chose to paint the enclosures the same color as the neighboring building behind them, making the plant even less visible from the street.
Another major consideration was making sure that the new power plant was configured to the existing emergency electrical distribution system that had previously been served by the old “roll up” generators. Entire switchboards were placed on the new plant, enabling it to interface with the Con Ed services distributed throughout vaults in three NYSE buildings via 24 automatic transfer switches. Coordinating all those switches and electrical interfaces was no easy task.
In fact, to successfully implement the new system, JB&B had to develop a 3-D modeling system for electrical feeder coordination. As planned through this program, the paralleling gear output distribution breakers now sequence their closing to allow downstream transformers to energize and avoid excessive load steps on the generator. In order to make sure critical systems could be maintained even with a generator malfunction, JB&B worked directly with emergency switchboard manufacturer ASCO to construct load-shedding algorithms that allow non-critical equipment to be disconnected safely. And the output from these algorithms can be displayed on flat screen panels at the paralleling gear enclosure, the building engineer’s office, or the chief electrical engineer’s office. Thanks to this feature, key operators can easily read the system status in both standbymode and during emergency operation. Certain non-essential equipment can even be automatically shed from the load by the emergency power system itself, virtually guaranteeing continued N+2 reliability for critical trading functions.
That a system of this intricacy was successfully implemented at all is quite an accomplishment. But to do it under budget and ahead of schedule makes the work of JB&B even more impressive and worthy of praise as the ARC Award emergency backup power system of the year.
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